Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.
A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)
Refraction of LIGHT effected by the media of the EYE.
A pair of ophthalmic lenses in a frame or mounting which is supported by the nose and ears. The purpose is to aid or improve vision. It does not include goggles or nonprescription sun glasses for which EYE PROTECTIVE DEVICES is available.
An objective determination of the refractive state of the eye (NEARSIGHTEDNESS; FARSIGHTEDNESS; ASTIGMATISM). By using a RETINOSCOPE, the amount of correction and the power of lens needed can be determined.
Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)
The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)
Application of tests and examinations to identify visual defects or vision disorders occurring in specific populations, as in school children, the elderly, etc. It is differentiated from VISION TESTS, which are given to evaluate/measure individual visual performance not related to a specific population.
Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.
The condition of where images are correctly brought to a focus on the retina.
A condition of an inequality of refractive power of the two eyes.
The use of statistical and mathematical methods to analyze biological observations and phenomena.
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
Agents that dilate the pupil. They may be either sympathomimetics or parasympatholytics.
Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)
A series of tests used to assess various functions of the eyes.
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition. Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.
A parasympatholytic anticholinergic used solely to obtain mydriasis or cycloplegia.
Persons with loss of vision such that there is an impact on activities of daily living.
Vision considered to be inferior to normal vision as represented by accepted standards of acuity, field of vision, or motility. Low vision generally refers to visual disorders that are caused by diseases that cannot be corrected by refraction (e.g., MACULAR DEGENERATION; RETINITIS PIGMENTOSA; DIABETIC RETINOPATHY, etc.).
The professional practice of primary eye and vision care that includes the measurement of visual refractive power and the correction of visual defects with lenses or glasses.
The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.
Surgical procedures employed to correct REFRACTIVE ERRORS such as MYOPIA; HYPEROPIA; or ASTIGMATISM. These may involve altering the curvature of the CORNEA; removal or replacement of the CRYSTALLINE LENS; or modification of the SCLERA to change the axial length of the eye.
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
Diseases affecting the eye.
The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.
The absence or restriction of the usual external sensory stimuli to which the individual responds.
The aperture in the iris through which light passes.
A form of ocular misalignment characterized by an excessive convergence of the visual axes, resulting in a "cross-eye" appearance. An example of this condition occurs when paralysis of the lateral rectus muscle causes an abnormal inward deviation of one eye on attempted gaze.
The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. (Cline et al., Dictionary of Visual Science, 4th ed, p109)
Pieces of glass or other transparent materials used for magnification or increased visual acuity.
The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.
Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)
The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)
The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.
The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.
Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)
Excessive axial myopia associated with complications (especially posterior staphyloma and CHOROIDAL NEOVASCULARIZATION) that can lead to BLINDNESS.
A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.
A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.
A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.
Measurement of distances or movements by means of the phenomena caused by the interference of two rays of light (optical interferometry) or of sound (acoustic interferometry).
A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.
A country in Southeastern Asia, northwest of Australia in the Lesser Sunda Islands at the eastern end of the Indonesian archipelago. It includes the eastern half of the island of Timor, the Oecussi (Ambeno) region on the northwest portion of the island of Timor, and the islands of Pulau Atauro and Pulau Jaco. On May 20, 2002, East Timor was internationally recognized as an independent state. This followed its declared independence from Portugal on November 20, 1975 and a period of armed conflict with Indonesia.
Gas lasers with excited dimers (i.e., excimers) as the active medium. The most commonly used are rare gas monohalides (e.g., argon fluoride, xenon chloride). Their principal emission wavelengths are in the ultraviolet range and depend on the monohalide used (e.g., 193 nm for ArF, 308 nm for Xe Cl). These lasers are operated in pulsed and Q-switched modes and used in photoablative decomposition involving actual removal of tissue. (UMDNS, 2005)
Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.
The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
A form of ocular misalignment where the visual axes diverge inappropriately. For example, medial rectus muscle weakness may produce this condition as the affected eye will deviate laterally upon attempted forward gaze. An exotropia occurs due to the relatively unopposed force exerted on the eye by the lateral rectus muscle, which pulls the eye in an outward direction.
The transparent, semigelatinous substance that fills the cavity behind the CRYSTALLINE LENS of the EYE and in front of the RETINA. It is contained in a thin hyaloid membrane and forms about four fifths of the optic globe.
Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.
The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
Incorrect diagnoses after clinical examination or technical diagnostic procedures.
Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.
Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.
One of the MUSCARINIC ANTAGONISTS with pharmacologic action similar to ATROPINE and used mainly as an ophthalmic parasympatholytic or mydriatic.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.
Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.
The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.
Soft, supple contact lenses made of plastic polymers which interact readily with water molecules. Many types are available, including continuous and extended-wear versions, which are gas-permeable and easily sterilized.
An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.
Method of making images on a sensitized surface by exposure to light or other radiant energy.
Measurement of the index of refraction (the ratio of the velocity of light or other radiation in the first of two media to its velocity in the second as it passes from one into the other).
A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.
A bilateral retinopathy occurring in premature infants treated with excessively high concentrations of oxygen, characterized by vascular dilatation, proliferation, and tortuosity, edema, and retinal detachment, with ultimate conversion of the retina into a fibrous mass that can be seen as a dense retrolental membrane. Usually growth of the eye is arrested and may result in microophthalmia, and blindness may occur. (Dorland, 27th ed)
The turning inward of the lines of sight toward each other.
A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include REFRACTIVE ERRORS; STRABISMUS; OCULOMOTOR NERVE DISEASES; TROCHLEAR NERVE DISEASES; ABDUCENS NERVE DISEASES; and diseases of the BRAIN STEM and OCCIPITAL LOBE.
Images seen by one eye.
Processes and properties of the EYE as a whole or of any of its parts.
The removal of a cataractous CRYSTALLINE LENS from the eye.
The inhabitants of a city or town, including metropolitan areas and suburban areas.
The blending of separate images seen by each eye into one composite image.
Presence of an intraocular lens after cataract extraction.
An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1)
The pressure of the fluids in the eye.
Nystagmus present at birth or caused by lesions sustained in utero or at the time of birth. It is usually pendular, and is associated with ALBINISM and conditions characterized by early loss of central vision. Inheritance patterns may be X-linked, autosomal dominant, or recessive. (Adams et al., Principles of Neurology, 6th ed, p275)
General disorders of the sclera or white of the eye. They may include anatomic, embryologic, degenerative, or pigmentation defects.
An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)
The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve.
Artificial implanted lenses.
Perception of three-dimensionality.
Measuring and weighing systems and processes.
Absence of the crystalline lens resulting from cataract extraction.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
The inhabitants of rural areas or of small towns classified as rural.
Heterogeneous group of autosomal recessive disorders comprising at least four recognized types, all having in common varying degrees of hypopigmentation of the skin, hair, and eyes. The two most common are the tyrosinase-positive and tyrosinase-negative types.
The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. It receives the tendons of insertion of the extraocular muscles and at the corneoscleral junction contains the canal of Schlemm. (From Cline et al., Dictionary of Visual Science, 4th ed)
A characteristic showing quantitative inheritance such as SKIN PIGMENTATION in humans. (From A Dictionary of Genetics, 4th ed)
A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)
Methods of detecting genetic etiology in human traits. The basic premise of twin studies is that monozygotic twins, being formed by the division of a single fertilized ovum, carry identical genes, while dizygotic twins, being formed by the fertilization of two ova by two different spermatozoa, are genetically no more similar than two siblings born after separate pregnancies. (Last, J.M., A Dictionary of Epidemiology, 2d ed)

Results of small incision extracapsular cataract surgery using the anterior chamber maintainer without viscoelastic. (1/740)

AIMS: To assess the efficacy of extracapsular cataract surgery using the anterior chamber maintainer (ACM) without the use of viscoelastic. To compare the effects of this surgical technique on non-diabetic and diabetic patients. METHODS: A prospective single armed clinical trial of 46 eyes in 46 patients undergoing cataract surgery using the ACM without viscoelastic. Patients were assessed preoperatively and at 3 weeks, 3 months, and 12 months postoperatively. The main outcome variables included visual acuity, surgically induced astigmatic change (SIAC), changes in endothelial cell density (ECD), and morphology affecting the central and superior regions of the cornea. RESULTS: Postoperatively, 56% and 70% of patients had unaided visual acuities of 6/12 or better at 3 weeks and 3 months respectively. Even after excluding those patients with pre-existing maculopathy (including diabetic maculopathy), there remains a significant difference between the non-diabetic and diabetic groups in terms of the proportion of patients attaining an unaided visual acuity of 6/12 or better at both 3 weeks (p = 0.003) and 3 months (p = 0.001). Three months postoperatively, the SIAC based upon the keratometric and refractive data was 1.1 dioptres (D) and 1.3 D respectively. There was no statistically significant difference in the SIAC when the non-diabetic and diabetic groups were compared. The mean central and superior endothelial cell losses at 3 months postoperatively were 16% and 22% respectively and at 12 months postoperatively were 20% and 25% respectively. The diabetic group demonstrated greater endothelial cell losses and a more marked and protracted deviation of endothelial cell morphology from normality when compared with the non-diabetic group; however, the differences did not reach statistical significance. CONCLUSIONS: The efficacy of small incision cataract surgery using the ACM in terms of visual outcome and induced astigmatism is comparable with the results obtained using other techniques that utilise a similar size of incision. However, in view of the magnitude and range of the endothelial cell losses associated with this technique the concurrent use of viscoelastic is suggested. There does not appear to be a statistically or clinically significant difference between non-diabetic and diabetic patients in terms of the magnitude of the endothelial cell losses or in the wound healing response in the 12 months after cataract surgery using the ACM.  (+info)

Tonic accommodation, age, and refractive error in children. (2/740)

PURPOSE: An association between tonic accommodation, the resting accommodative position of the eye in the absence of a visually compelling stimulus, and refractive error has been reported in adults and children. In general, myopes have the lowest (or least myopic) levels of tonic accommodation. The purpose in assessing tonic accommodation was to evaluate it as a predictor of onset of myopia. METHODS: Tonic accommodation was measured in children enrolled in the Orinda Longitudinal Study of Myopia using an infrared autorefractor (model R-1; Canon, Lake Success, NY) while children viewed an empty lit field or a dark field with a fixation spot projected in Maxwellian view. Children aged 6 to 15 years were measured from 1991 through 1994 (n = 714, 766, 771, and 790 during the 4 years, successively). Autorefraction provided refractive error and tonic accommodation data, and videophakometry measured crystalline lens curvatures. RESULTS: Comparison of the two methods for measuring tonic accommodation shows a significant effect of age across all years of testing, with the lit empty-field test condition yielding higher levels of tonic accommodation compared with the dark-field test condition in children aged 6 through 11 years. For data collected in 1994, mean (+/-SD) tonic accommodation values for the lit empty-field condition were significantly lower in myopes, intermediate in emmetropes, and highest in hyperopes (1.02 +/- 1.18 D, 1.92 +/- 1.59 D, and 2.25 +/- 1.78 D, respectively; Kruskal-Wallis test, P < 0.001; between-group testing shows each group is different from the other two). Age, refractive error, and Gullstrand lens power were significant terms in a multiple regression model of tonic accommodation (R2 = 0.18 for 1994 data). Lower levels of tonic accommodation for children entering the study in the first or third grades were not associated with an increased risk of the onset of myopia, whether measured in the lit empty-field test condition (relative risk = 0.90; 95% confidence interval = 0.75, 1.08), or the dark-field test condition (relative risk = 0.83; 95% confidence interval = 0.60, 1.14). CONCLUSIONS: This is the first study to document an association between age and tonic accommodation. The known association between tonic accommodation and refractive error was confirmed and it was shown that an ocular component, Gullstrand lens power, also contributed to the tonic accommodation level. There does not seem to be an increased risk of onset of juvenile myopia associated with tonic accommodation.  (+info)

The effects of spectacle wear in infancy on eye growth and refractive error in the marmoset (Callithrix jacchus). (3/740)

We made a comprehensive study, involving observations on 45 marmosets, of the effects on ocular growth and refraction of wearing spectacles from the ages of 4-8 weeks. This period was within the period early in life when the eye grows rapidly and refraction changes from hyperopia to its adult value of modest myopia. In one series of experiments we studied the effect of lenses of powers -8, -4, +4 and +8D fitted monocularly. In another series of experiments we studied the effect of lenses of equal and opposite powers fitted binocularly, with the two eyes alternately occluded, so as to give an incentive to use both eyes, and in particular to accommodate, for at least part of each day, through the negative lens. The vitreous chamber of eyes that wore negative lenses of -4D or -8D, combined with alternate occlusion, elongated more rapidly than that of the fellow eye (negative lens eye-positive lens eye, 0.21 +/- 0.03 mm (S.E.M.), P < 0.01 and 0.25 +/- 0.06 mm, P < 0.05, respectively) and became relatively more myopic (2.8 +/- 0.26D, P < 0.01 and 2.4 +/- 0.61D, P < 0.05 respectively). Eyes that wore -4D lenses monocularly elongated more rapidly and became myopic than fellow eyes. Eyes that wore +4D or +8D lenses were less strongly affected: animals that wore +8D lenses monocularly (without alternate occlusion) developed a slight relative hyperopia (0.99 +/- 0.21D, P < 0.01), with the more hyperopic eyes also slightly shorter (0.09 +/- 0.05 mm) than their fellow eyes, but eyes wearing +4D lenses were not significantly different from their fellow eyes. Animals that wore -8D lenses monocularly (without alternate occlusion) developed a slight relative hyperopia after three weeks of lens-wear (0.85 +/- 0.26D, P < 0.05). These were the only eyes that responded in a non-compensatory direction to the optical challenge of spectacle wear, and we interpret this effect as one due to visual deprivation. After the removal of lenses, the degree of anisometropia slowly diminished in those groups of animals in which it had been induced, but in the three groups in which the largest effects had been produced by lens-wear the overall mean anisometropia (0.68 +/- 0.24D, P < 0.01) and vitreous chamber depth (VCD) discrepancy (0.09 +/- 0.03 mm, P < 0.01) were still significant at the end of the experiments, when the animals were 273 days old. The reduction of anisometropia in these groups was associated with an increase in the rate of elongation of the vitreous chamber in the eyes that had previously grown normally i.e. the less myopic eyes grew more rapidly than their fellow eyes: in the seven weeks following lens-wear these eyes became more myopic and longer than normal eyes (refraction P < 0.001; VCD P < 0.001). Control experiments showed that occlusion of one eye for 50% of the day had no effect on eye growth and refraction, and therefore that alternate occlusion itself had no effect.  (+info)

Off-axis monochromatic aberrations estimated from double pass measurements in the human eye. (4/740)

Off-axis monochromatic aberrations in the human eye impose limits on peripheral vision. However, the magnitude of the aberrations off-axis, and in particular coma, has not been yet completely determined. We have developed a procedure to estimate third order aberrations in the periphery of the human eye. The technique is based on recording series of double pass retinal images with unequal entrance and exit pupil diameters (Artal, Iglesias, Lopez-Gil & Green (1995b). J. Opt. Soc. Am. A, 12, 2358-2366.) which allows the odd asymmetries in the retinal image be assessed. The procedure that is described provides accurate estimates of the main off-axis aberrations: astigmatism, defocus and coma. We have measured these aberrations in four normal subjects. For a given eccentricity, the measured amount of coma and astigmatism are relatively similar among subjects, because the angular distance from the axis is the dominant factor in determining the magnitude of these aberrations. However, we found considerable variability in the values of peripheral defocus, probably due to a complicate combination of off-axis aberrations and fundus shape. The final off-axis optical performance of the eye for a given object location is determined by a particular mixture of defocus, astigmatism, coma and higher order aberrations.  (+info)

Abnormal tear dynamics and symptoms of eyestrain in operators of visual display terminals. (5/740)

OBJECTIVES: To clarify the relation between the prevalence of dry eye syndrome and subjective symptoms of asthenopia in visual display terminal (VDT) operators. METHOD: 722 VDT workers (242 subject workers with symptoms of asthenopia and 480 controls without such symptoms) without obvious organic ocular diseases received an ophthalmological examination consisting of refractometry and a tear function (phenol red thread) test. RESULTS: More than 30% of symptomatic workers were found to meet the criteria of dry eye, and the odds ratio compared with the controls was 4.61 (p < 0.001). This odds ratio was significantly greater than that obtained for refractive errors (2.31). CONCLUSIONS: Although this cross sectional study could not prove that dry eyes are the cause of asthenopia, the profound association of dry eyes with symptoms of asthenopia could be verified. It would be useful to carry out tear function tests in workers with symptoms of asthenopia.  (+info)

Changes in refractive error over a 5-year interval in the Beaver Dam Eye Study. (6/740)

PURPOSE: To examine changes in spherical equivalent over a 5-year period in persons 43 to 84 years of age. METHODS: All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990) and a 5-year follow-up examination (1993-1995). Refractions were determined according to the same protocol at both examinations. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 3007 right eyes and 3012 left eyes of the 3684 people participating in both examinations. RESULTS: Right and left eyes behaved similarly. Spherical equivalent became more positive in the youngest subjects and more negative in older subjects. After adjusting for other factors, the 5-year change in spherical equivalent of those 45, 55, 65, and 75 years of age was +0.15, +0.18, +0.10, and -0.07D, respectively. Severity of nuclear sclerosis was related to the amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.2 D, whereas those with severe nuclear sclerosis had a change of -0.5 D. The amount of change was also related to gender, diabetes, and age at onset of myopia. It was unrelated to education and baseline spherical equivalent. CONCLUSIONS: Changes in spherical equivalent over a 5-year period were small. Before the age of 70, people became more hyperopic. After the age of 70, people became more myopic. Much of the myopic change may be related to increasing nuclear sclerosis.  (+info)

Amblyopia and visual acuity in children with Down's syndrome. (7/740)

BACKGROUND/AIMS: Amblyopia in people with Down's syndrome has not been well investigated. This study was designed to determine the prevalence and associated conditions of amblyopia in a group of home reared children with Down's syndrome. METHODS: All children in the study group underwent an evaluation of visual acuity. In addition, previous ophthalmological records were reviewed, and a subgroup of children was examined. For the purposes of this study, amblyopia was defined quantitatively as a difference of two Snellen acuity lines between eyes or if unilateral central steady maintained (CSM) vision and a clear fixation preference was observed. A high refractive error was defined as a spherical equivalent more than 3 dioptres and astigmatism more than 1.75 dioptres. Anisometropia was defined as a difference of at least 1.5 dioptres of sphere and/or 1.0 dioptre of cylinder between eyes. 68 children with Down's syndrome between the ages of 5 and 19 years were enrolled in the final study group. RESULTS: Amblyopia was observed in 15 (22%) of 68 patients. An additional 16 (24%) patients had bilateral vision less than 20/50. Strabismus, high refractive errors, and anisometropia were the conditions most commonly associated with decreased vision and amblyopia CONCLUSION: This study suggests that the prevalence of amblyopia is higher than previously reported. Fully 46% of these children with Down's syndrome had evidence of substantial visual deficits. These patients may be at higher risk for visual impairment and should be carefully examined for ophthalmological problems.  (+info)

Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study. (8/740)

PURPOSE: To assess the prevalence, distribution, and demographic associations of refractive error in an urban population in southern India. METHODS: Two thousand five hundred twenty-two subjects of all ages, representative of the Hyderabad population, were examined in the population-based Andhra Pradesh Eye Disease Study. Objective and subjective refraction was attempted on subjects >15 years of age with presenting distance and/or near visual acuity worse than 20/20 in either eye. Refraction under cycloplegia was attempted on all subjects < or =15 years of age. Spherical equivalent >0.50 D in the worse eye was considered as refractive error. Data on objective refraction under cycloplegia were analyzed for subjects < or =15 years and on subjective refraction were analyzed for subjects >15 years of age. RESULTS: Data on refractive error were available for 2,321 (92.0%) subjects. In subjects < or =15 years of age, age-gender-adjusted prevalence of myopia was 4.44% (95% confidence interval [CI], 2.14%-6.75%), which was higher in those 10 to 15 years of age (odds ratio, 2.75; 95% CI, 1.25-6.02), of hyperopia 59.37% (95% CI, 44.65%-74.09%), and of astigmatism 6.93% (95% CI, 4.90%-8.97%). In subjects >15 years of age, age-gender-adjusted prevalence of myopia was 19.39% (95% CI, 16.54%-22.24%), of hyperopia 9.83% (95% CI, 6.21%-13.45%), and of astigmatism 12.94% (95% CI, 10.80%-15.07%). With multivariate analysis, myopia was significantly higher in subjects with Lens Opacity Classification System HI nuclear cataract grade > or =3.5 (odds ratio, 9.10; 95% CI, 5.15-16.09), and in subjects with education of class 11 or higher (odds ratio, 1.80; 95% CI, 1.18-2.74); hyperopia was significantly higher in subjects > or =30 years of age compared with those 16 to 29 years of age (odds ratio, 37.26; 95% CI, 11.84-117.19), in females (odds ratio, 1.86; 95% CI, 1.33-2.61), and in subjects belonging to middle and upper socioeconomic strata (odds ratio, 2.10; 95% CI, 1.09-4.03); and astigmatism was significantly higher in subjects > or =40 years of age (odds ratio, 3.00; 95% CI, 2.23- 4.03) and in those with education of college level or higher (odds ratio, 1.73; 95% CI, 1.07-2.81). CONCLUSIONS: These population-based data on distribution and demographic associations of refractive error could enable planning of eye-care services to reduce visual impairment caused by refractive error. If these data are extrapolated to the 255 million urban population of India, among those >15 years of age an estimated 30 million people would have myopia, 15.2 million hyperopia, and 4.1 million astigmatism not concurrent with myopia or hyperopia; in addition, based on refraction under cycloplegia, 4.4 million children would have myopia and 2.5 million astigmatism not concurrent with myopia or hyperopia.  (+info)

V. Prevalence of refractive error in school children. 49± 2. Background: Uncorrected refractive error is the leading cause of eye problem and the second cause of blindness worldwide. . Only 10. 3. To assess the prevalence of refractive error and related visual impairment in school-aged children in the rural population of the Mahabubnagar district REFRACTIVE ERROR BLINDNESS OF REFRACTIVE ERRORS WORLD-WIDEStudies around the world indicate that refractive errors are common in all ages. 3 billion people worldwide have refractive errors out of The Refractive Error Study in Children (RESC) examined the prevalence of . 9% children were ever A study on the prevalence of refractive errors among school childern of 7-15 years The prevalence of uncorrected refractive error in urban and rural children hyperopia, myopia, presbyope, presbyopia, uncorrected refractive error In southern India, Nirmalan et al (5) found a prevalence of 55 per cent in people aged Dec 3, 2015 Introduction: Uncorrected refractive ...
Refractive error, also known as refraction error, is a problem with focusing light accurately onto the retina due to the shape of the eye. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain. Near-sightedness is due to the length of the eyeball being too long, far-sightedness the eyeball too short, astigmatism the cornea being the wrong shape, and presbyopia aging of the lens of the eye such that it cannot change shape sufficiently. Some refractive errors occur more often among those whose parents are affected. Diagnosis is by eye examination. Refractive errors are corrected with eyeglasses, contact lenses, or surgery. Eyeglasses are the easiest and safest method of correction. Contact ...
Refractive errors are the most common eye disorders. Most people have a refractive error, but it is usually too small to affect their vision significantly. For the eye to see clearly, light rays must be bent, or refracted, by the cornea and the lens and focused on the retina. The retina receives the light rays and converts them to neural signals that are transmitted by the optic nerve to the brain, where the signals are translated into images.. Like a camera, the human eye must be properly focused to see an image clearly. If light does not bend or refract correctly and focus directly on the retina, the result is blurred vision, or a refractive error.. The four most common refractive errors are:. ...
Parents of children with anisometropia ≥ 2.00D were also more likely to have developmental concerns (OR= 2.61; 95% CI: 1.07 - 6.34).Table 5Association of significant refractive errors with parental report of Refractive Errors Physicians Locations Was this helpful? The odds of parental concerns about development significantly increased in children older than 36 months with hyperopia ≥ 3.00D, astigmatism ≥ 1.50D, or anisometropia ≥ 2.00D.ConclusionsParental concerns about general developmental problems Normal Refractive Error In Children It is possible to have astigmatism in combination with myopia or hyperopia.. PreviousNormal Vision Development in Babies and ChildrenNextChildhood Eye Diseases and Conditions Leer en Español: Errores Refractivos en los Niños Due to the potential consequences of uncorrected refractive errors, children whose parents have expressed concerns regarding development should be referred for an eye examination with cycloplegic refraction to rule out significant ...
Purpose: Refractive error is the most common eye disorder worldwide, and a prominent cause of blindness. Myopia affects over 30% of Caucasian populations, and up to 80% of Asians. We aimed to identify multiple genetic loci that explain the genetic architecture of refractive error.. Methods: The Consortium for Refractive Error and Myopia (CREAM) conducted genome-wide meta-analyses including 37,382 individuals from 27 Caucasian studies, and 8,376 from 5 Asian cohorts. Identified variants were used for genetic risk score assessment.. Results: We identified 16 new loci for refractive error in Caucasians, of which 10 were shared with Asians. Combined analysis revealed 8 additional new loci. The new loci include genes with function in neurotransmission (GRIA4), ion channels (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2, BMP2), and eye development (SIX6, PRSS56). We also confirmed previously reported associations with GJD2 (top SNP rs524952; Pcombined=1.44x10-15) and ...
Purpose.: To provide data on prevalence and types of refractive error and the spectacle-wearing rate among adults in Nigeria and the degree to which the need for distance correction could be met by off-the-shelf spectacles. Methods.: Multistage, stratified, cluster random sampling with probability proportional to size was used to identify a nationally representative sample of 15,027 persons aged ≥40 years. Distance vision was measured using a reduced logMAR tumbling-E chart. All participants underwent autorefraction, and those with presenting acuity of ,6/12 in one or both eyes had their corrected acuity measured and underwent detailed clinical examination to determine the cause. Results.: Included in the survey were 13,599 (89.9%) of the 15,122 persons aged ≥40 years who were enumerated. Uncorrected refractive error was responsible for 77.9% of mild visual impairment (,6/12-6/18), 57.1% of moderate visual impairment (,6/18-6/60), 11.3% of severe visual impairment (,6/60-3/60), and 1.4% of ...
Purpose : To determine the relationship between refractive errors and ocular components values in carpet weavers Methods : Refractive errors and ocular components values were investigated on carpet weavers at Mashhad city in Iran . After selection of samples, the individuals who had ophthalmic and systemic disease effective on the refractive errors were ...
The most common types of refractive errors are myopia, hyperopia, presbyopia, and astigmatism.. Myopia (nearsightedness) is a condition where objects up close appear clearly, while objects far away appear blurry. With myopia, light comes to focus in front of the retina instead of on the retina.. Hyperopia (farsightedness) is a common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects at any distance, near or far.. Astigmatism is a condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out.. Presbyopia is an age-related condition in which the ability to focus up close becomes more difficult. As the eye ages, the lens can ...
Background: Uncorrected refractive errors are the main cause of vision impairment in school-aged children. The current study focuses on the effectiveness of school eye screening in correcting. refractive errors. Objectives: 1. To study the magnitude of visual impairment among school children. 2. To assess the compliance of students for refraction testing, procurement and use of spectacles. Materials and Methods: An intervention study was conducted in schools of the north-west district of Delhi, in the rural field practice area of a medical college. Students studying in five government schools in the field practice area were chosen as the study subjects. Results: Out of 1123 students enrolled, 1075 (95.7%) students were screened for refractive errors. Low vision (visual acuity ,20/60) in MG-132 solubility dmso the better eye was observed in 31 (2.9%) children INCB28060 inhibitor and blindness (visual acuity ,20/200) in 10 (0.9%) children. Compliance with referral for refraction was very low as ...
Contact lenses  Toric contact lenses Soft lenses [SL] Rigid gas permeable lenses [RGP] RGP do not conform to the asymmetry of corneal surface but replaces it totally and also provides F. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Laser Sub-Epithelial Keratomileusis• LASEK can treat mild to moderate myopia and hyperopia +/- astigmatism.• Can be performed as an outpt with topical anesthesia• The corneal epithelium is incompletely incised using a PowerPoint Presentation Wave Aberration: Astigmatism Wave Aberration: Coma Wave Aberration: ... , PowerPoint PPT presentation , free to view GPS Error - The accuracy of GPS signals was intentionally degraded by For a small fee you can get the industrys best online privacy or publicly promote your presentations and slide shows with top rankings. Refractive Error In Children Ppt Anisometropia• Difference in refractive power between 2 eyes• refractive correction often leads to ...
A method of measuring the refractive error of the eye uses a digital computer and directs a variable focus, variable orientation light pattern on the eye, detects the light pattern reflected from the retina to produce an analog signal as a function of the focus of the reflected pattern, and converts the analog signal to a digital signal stream fed to the computer. The computer varies the focus of the pattern and the orientation of the pattern and selects and stores results from the digital signal stream. It then fits a sine wave to the selected signal results, and calculates the refractive error from the sine wave.
What are Refractive Errors? In refractive errors, the shape of the eye prevents light from focusing on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea,
Slight alterations in vision should never be neglected. Its very important to get eye examinations by trained ophthalmologists and optometrists, employing advanced equipment. Uncorrected refractive errors can lead to impaired development of vision in children, as well as amblyopia or lazy vision and squinting of eyes.. Refractive errors are of 3 types:. Myopia or short-sightedness: In myopia the rays of light coming from a distant target get focused at a point in front of the retina. Glasses or contact lenses with a minus power are prescribed to focus the image onto the retina.. Hyperopia or long-sightedness: In hyperopia the rays of light coming from a distant target get focused at a point behind the retina. Glasses or contact lenses with a plus power are prescribed to focus the image onto the retina.. Astigmatism or cylindrical power: In astigmatism the rays of light coming from a distant target cannot focus at a single point on the retina. Doctors prescribe lenses of a different curvature to ...
Methods The study participants underwent a detailed ophthalmic examination according to a standardised protocol. Refractive error was determined by an automatic refraction device (Humphrey HARK 599) without cycloplegia. Definitions for the analysis were myopia ,−0.5 dioptres (D), hyperopia ,+0.5 D, astigmatism ,0.5 cylinder D and anisometropia ,1.0 D difference in the spherical equivalent between the eyes. Exclusion criterion was previous cataract or refractive surgery.. ...
Refractive errors comprise a group of diseases which can be corrected by refractive corrections i.e. by using glasses, or contact lens. These are myopia,
AIM: To describe the clinical characteristics and late results of patients with retinopathy of prematurity (ROP) treated with 6h cryotherapy. METHODS: Out of 1252 infants screened for ROP, 52 patients were treated with temporal 6h cryotherapy from 1997 to 2005 were recalled to our clinic. Among these 23 patients were available and 46 eyes of 23 infants were included to evaluate for visual acuity, refractive error, ocular alignment, nystagmus, retinal examination (abnormal branching of retinal vessels, retinal thinning, latis degenerations, tortuosity of vessels, straightening of temporal vessels, narrowing of the angle of vessel in the juxtapapillary entrance, pigment changes, macular heterotopia), optic atrophy and optic disc cupping, axial length at birth and axial length at 1y ...
Astigmatism is one type of refractive error. Its a condition in which an abnormal curvature of the cornea can cause two focal points to fall in two different locations-making objects up close and at a distance appear blurry.
Hans Limburg The first pre-requisite for improving the results of surgery is to monitor surgical outcomes. This book summarises the work of one of the most expert researchers in this field. It is a valuable resource for anyone involved in cataract surgery delivery. A separate chapter deals with school screening for refractive errors. A limited…
Read explanations about common focusing problems and refractive errors that many people face. Austin Eye offers solutions to many of these eye problems.
Vol 9: Assessing the Accuracy and Feasibility of a Refractive Error Screening Program Conducted by School Teachers in Pre-Primary and Primary Schools in Thailand.. This article is from PLoS ONE, volume 9.AbstractIntroduction: As part of the development of a system for the screening o. Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Investigators: Ma Khin Pyi Son, BA, Mayo Medical School; David O. Hodge, MS, Department of Health Sciences Research, Mayo Clinic and Mayo Foundation; Brian G. Mohney, MD, Department of Ophthalmology, Mayo Clinic and Mayo Foundation. Mentor: Brian G. Mohney, MD, Department of Ophthalmology, Mayo Clinic Introduction: Despite the common occurrence of refractive errors in infancy, their management has not been standardized among clinicians. While some clinicians prescribe spectacles to minimize blur, distorted visual stimuli are thought to advance the emmetropization process. The purpose of this study was to evaluate the natural history of refractive error among infants.. Methods: The medical records of all patients diagnosed with moderate refractive errors (myopia -0.75 to -4.0; hyperopia ≥ +3.50; and astigmatism ≥ 2.00) within the first year of life, from January 1, 1990, through December 31, 2000, were retrospectively reviewed. Children with a history of strabismus or intraocular or ...
In the elderly population, accidental falls present a significant health hazard and can result in lasting disability or even death. Falls in the elderly are often attributed to declining vision. A recent study conducted at the UC Davis Health System Eye Center took a look at the larger adult population and found some interesting correlations between eyesight and the sense of balance. In an effort to better understand how vision contributes to falls, researchers set out to compare the balance ability in groups of adults aged 40 and over who had normal vision, visual impairment, and uncorrected refractive error (blurred vision that could be remedied with corrective lenses). This study involved 4,590 adults and is the first large-scale survey to objectively measure balance as it relates to vision. Participants were assessed for their ability to stand with feet together throughout increasingly challenging conditions: firm surface or soft foam surface with eyes both opened and closed during separate ...
Eye disorders in children are either refractive or non-refractive errors. Refractive errors are those caused by the shape of the eye. Non-refractive errors are caused by disease.
An academic, researcher, educator and internationally celebrated public health leader, Professor Kovin Naidoo has been revolutionising access and delivery to eye care for the disadvantaged throughout the world. A powerful public health advocate, he has devoted his working life to reducing avoidable blindness and vision impairment, with specific emphasis on refractive error.
In regards to children, VA is included in virtually all public health screening programs, with the aim to detect amblyopia and/or significant refractive errors,7,8 and its value is indeed used as a criterion for referral for further evaluation and early treatment.9,10. Many important decisions are based on the measurement of visual acuity, and yet, up until now, the tests and scoring systems used by different practitioners were neither standard nor accurate, and often not even equivalent. The need for widespread use of standardized VA tests that may provide reliable and precise VA measurements is crucial;11 not only for recording correct initial values in a given patient, but also for identifying a true change in VA12 when a patient obtains a different score in another occasion and/or when checked by a different practitioner. This will also prevent unnecessary false positive and negative referrals amongst healthcare practitioners.. Furthermore, communication amongst different professionals ...
An electro-active spectacle lens is disclosed. The disclosed lens includes a first lens optic. The disclosed lens also includes a first electro-active zone positioned in a cooperative relationship with the first lens optic. In certain embodiments, the electro-active lens includes a range finder positioned in a cooperative relationship with the electro-active lens.
Having an initial LASIK correction for high nearsightedness, farsightedness or astigmatism, and being older than 40 years of age, increase the chances
SouthWest Vision is your local optometrist in St George serving all of your vision care needs. Call us today at 435-673-5577 for an appointment.
SouthWest Vision is your local optometrist in St George serving all of your vision care needs. Call us today at 435-673-5577 for an appointment.
If you decide to have laser eye surgery to correct a refractive error, speak to your optometrist (optician) first. They can advise you on the procedure and recommend clinics in your area. Guidelines from the Royal College of Ophthalmologists (RCOphth) say that only registered surgeons with specialist training should carry out laser surgery.. Most clinics that carry out laser surgery for refractive errors will require you to:. ...
If you decide to have laser eye surgery to correct a refractive error, speak to your optometrist (optician) first. They can advise you on the procedure and recommend clinics in your area. Guidelines from the Royal College of Ophthalmologists (RCOphth) say that only registered surgeons with specialist training should carry out laser surgery.. Most clinics that carry out laser surgery for refractive errors will require you to:. ...
Authors: Pirro G Hysi, Omar A Mahroo, Phillippa Cumberland, Robert Wojciechowski, Katie M Williams, Terri L Young, David A Mackey, Jugnoo S Rahi, Christopher J Hammond
Using data for more than half a million individuals, researchers identified 449 refractive area-related loci, including 336 sites not linked to the eye condition in the past.
A new visual screening process (PediaVision) is available to pediatricians and can take less than 5 seconds to complete and can assist in the detection of refractive errors, media opacities, and other abnormalities.
RECOMMENDED: If you have Windows errors then we strongly recommend that you download and run this (Windows) Repair Tool.. Dec 13, 2016. 50; , Xinming Zhang, E8031-E8040, doi: 10.1073/pnas.1605748113. with their averages and SDs (also indicated by the error bars) shown.. arcserve error e8031. Phone: Company: Customer Type: Select Customer TypeEnd CustomerTrial CustomerResellerDistributerMSP Arcserve Employee Language.. Nov 25, 2009. 2009; 4(11): e8031. (Note that errors of 0.00 indicate a truncated error that was ≤0.005.). FRET Transfer Rate and Error Calculations.. Error E8031. Failed to mark Drive [device #] [drives serial #] as OFF-LINE in Library [device #] [drives serial #]. Module: Library. Reason: This error message.. Changer Library Messages 8020 through 8046. To view information about a message, click the message number. Error E8020. Home , brightstor error , brightstor error e8031 brightstor error e8031. Related content. brightstor error.. Error E8031. Error al marcar la unidad [nº ...
How to Customize Error Pages: In Symfony applications, all errors are treated as exceptions, no matter if they are just a 404 Not Found error or a fatal error triggered by throwing some exception in y...
The difference between an estimated value and the population true value is called an error. There are two kind of errors: Sampling and nonsampling errors.
d error issue with d error message still appears evenafter trying suggested resolution - Samsung VP-D361 Mini DV Digital question
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Sources of error are the factors that influence a test score or item performance that are extraneous to the construct of interest. Because these are not related to the construct, they are errors in...
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Hi, Im quite new to using Qsort function. Have encountered problem with this error error C2664: qsort : cannot convert parameter 4 from int (const void *,const void *) to int (__cdecl...
So, I am on version 1903, but I did see updates for 1903 and an optional update for 1909. I tried to install both, but they fail. The error says, There were problems installing some updates, but well try again later. I tried running the troubleshooter, but it did not find any solutions. I tried sfc scannow and the dism command and both came up with an error too. Anyone else with this problem?. ...
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Uncorrected refractive error is the leading cause of visual impairment; 48.9% globally and 62.9% in South Asia (Bhutan is part of this region) as estimated by the Vision Loss Expert Group (VLEG). Recent studies document a wide global variation in the prevalence of refractive error and predict that without control interventions the prevalence of myopia will significantly increase globally, affecting nearly 5 billion people by 2050. Considering its high prevalence and significant socioeconomic impact, refractive error has gained priority as a public health challenge, particularly in children.. Bhutan did not have any authentic evidence on prevalence of visual impairment due to uncorrected refractive error in the country. The WHO Global Action Plan 2014-2019 emphasized evidence generation for blindness and visual impairment and evidence-based planning and intervention. To do so, IAPB SEA, Primary eye care department of Ministry of Health , Royal Government of Bhutan carried out a nation-wide survey ...
Purpose: To compare the mean difference of visual acuity as measured by auto refraction and subjective refraction.. Study Design: Descriptive cross-sectional study.. Place and Duration of Study: Department of ophthalmology, Services hospital Lahore from November 2013 to April 2014.. Material and Methods: Using non-probability consecutive sampling 300 eyes of 300 patients fulfilling inclusion criteria were recruited through OPD registration slip. Demographic data including age and gender was recorded. Complete ophthalmic examination was performed. This included measurement of refractive error by auto-refraction as well as subjective refraction. Detailed anterior segment examination with slit lamp and dilated fundus examination with indirect ophthalmoscopy was performed. The collected data was analyzed by using software SPSS version 17.. Results: The mean age of patients was 34.71 ± 7.45 years. There were 156 (52%) males and 144 (48%) females. There were 263 (87.69%) patients who had visual ...
Vision disorders are irregularities or abnormalities either of the eye, visual pathway, or brain, which affect ones ability to see. In healthy vision, visual acuity-often referred to as 20/20 vision-develops rapidly by three to six months of age and generally decreases rapidly as people approach 45. Poor visual acuity is often correctable with glasses or contact lenses. However, many other factors affect humans ability to see-some preventable or correctable and others not. Vision disorders may manifest from refractive errors, defective eye muscles, cataracts, lens displacement, glaucoma, fundus conditions, color vision deficits, eyelid conditions, orbital diseases, eye injuries, and optic nerve and visual pathway damage.. ...
Aims: To establish the prevalence of heterophoria and its association with refractive error and ethnicity in a population-based study of Australian school children.. Methods: The Sydney Myopia Study is a stratified, random cluster (school-based) sample of 4093 students (examined: 2003-2005). Two samples aged 6 (n=1692) and 12 years (n=2289) without heterotropia were included. Prevalent heterophoria was assessed using cover un-cover and prism bar alternate cover testing at 33cm and 6m distance fixation. Cycloplegic auto-refraction (1% cyclopentolate) was performed. Significant refractive error was defined as ≤-0.50SE and ≥+2.00SE.. Results: Exophoria was highly prevalent at near fixation (age 6: 58.3%, age 12: 52.2%). Orthophoria predominated at distance fixation (age 6: 85.4%, age 12: 90.9%). Hyperopia was associated with esophoria at near (age 6: odds ratio [OR] 1.7, 95% confidence interval (CI) 1.1-2.8, age 12: OR 2.9, CI 1.1-2.8) and distance fixation (age 6: OR 9.7, CI 3.5-26, age 12: ...
Eyeglasses are the simplest and safest way to correct refractive errors. Eyeglass lenses are designed with precise curves to refract light to the degree necessary to compensate for refractive errors. Your eye care professional can prescribe lenses that will provide you with optimal vision. Contact lenses are a safe and effective option if fitted and used properly. They often provide clearer vision, a wider field of vision and greater comfort than glasses. You may not be able to wear contact lenses if you have certain eye conditions. Refractive surgery permanently changes the shape of the cornea. This change in eye shape restores the focusing power of the eye by allowing the light rays to focus precisely on the retina for improved vision. There are several types of refractive surgeries, but the most popular are: ...
What are refractive errors? Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyebal
On World Sight Day, eye care organisations around the world take note of new data that shows that global eye care efforts are at serious risk of being overwhelmed-unless we act now. New data published in the Lancet Global Health shows that decades of declining avoidable blindness-those with uncorrected refractive errors and cataract-is plateauing, and is projected to increase between 2015 and 2050.. The International Agency for the Prevention of Blindness (IAPB), an international alliance of eye care organisations, has launched the IAPB Vision Atlas with the latest global data and evidence on blindness and vision impairment this World Sight Day (12 October 2017).. A new paper by the Vision Loss Expert Group (VLEG) published yesterday in the Lancet Global Health identifies the leading causes of Blindness and Moderate and Severe Vision Impairment (MSVI) in 2015. Of the 253 million people who are blind or MSVI, uncorrected refractive errors (123.8 million people) and cataract (65.2 million) are ...
Refractive Error Refractive error occurs if the eye cannot focus light properly on the retina. It may cause blurry vision. If your child shows any signs of
DR MCQUAID: So the objectives of my talk today are hopefully that when were done here you will, first of all, be able to describe some ways in which to gain a childs trust, so that you can actually make a vision assessment, and perform some retinoscopy or refraction. Id like you to be able to name a few conditions which can be revealed by your first impression of seeing the child, and some very simple binocular assessments. You should be able to explain when were done here why retinoscopy is such an important, vital skill to have when it comes to dealing with children. And then you should also be able to mention a couple of ways to manage pediatric refractive error. So now the thing is - is Im not going to stand up here and teach you how to did retinoscopy or how to do refraction on a child or anybody else. What Im gonna do here is just give you some insight and some quick non-confrontational-type tests, and that sort of thing. Im going to assume that many, if not most of you, at least ...
Poor vision is the most common impairment affecting school aged children in the developing world, comprising 48% of all disability among children aged 5 to 9 years in the India census of 2001.1 The leading and most easily remedied cause of visual impairment (visual acuity ,6/18) among children is refractive error, affecting 12.8 million children aged between 5 and 15 years, half of whom live in China.2 Spectacles provide a safe and inexpensive treatment. Several studies report that children with uncorrected refractive errors have lower scores on a variety of motor and cognitive tests,3 4 5 6 and that improvements in reading may occur when vision problems are corrected.6 7. However, the relation between academic achievement and refractive error may be complex. Hyperopia (far sightedness), causing difficulty in seeing close objects, is more likely to cause reading problems and is the focus of many studies of refractive error and school performance.5 6 Myopia (near sightedness) causes difficulty in ...
Methods: The study included 133 eyes of patients with normal-pressure glaucoma who were prospectively examined as part of the Erlanger Glaucoma Registry. Mean age was 55.50 ± 9.99 years, mean refractive error was -0.57 ± 2.61 diopters. The glaucoma group was compared with an age adapted normal control group consisting of 159 eyes of normal persons with a mean age of 54.75 ± 7.58 years and a mean refractive error of -0.13 ± 1.28 diopters. For all patients and subjects, 15 degree color stereo optic disc photographs were taken and morphometrically examined. Additionally, the mean capillary blood flow within the neuroretinal rim was measured by confocal laser scanning flowmetry (Heidelberg Retinal Flow Meter ...
Treatments for farsightedness Type of correction Advantages Disadvantages Eyeglasses The simplest, safest way to correct refractive errors, such as farsightedness, nearsightedness, and astigmatism Most people can wear glasses. Accurate and predictable vision correction to within 0.50 diopters of the desired result Less...
Annual Total Burden to the U.S. Economy of AMD, Cararact, Diabetic Retinopathy, Glaucoma, Refractive Errors, Visual Impairment and Blindness
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Three months postoperately, the mean UDVA (logMAR) improved significantly from 1.2±0.42 to 0.35±0.18 (p
Eye Problems: Find out about Refractive Errors including Astigmatism, Cataracts, Hyperopia, Myopia, Presbyopia. Also discover causes and treatment
Abstract. Objectives: To provide a description of refractive errors in healthy, term-born children, aged 1 through 24 months, and to test the hypothesis that spherical equivalent becomes significantly less hyperopic and less variable with increasing age.Methods: This is a prospective, cross-sectional design, cycloplegic retinoscopy was used to measure the refractive error in both eyes of 100 healthy, term- born children in four age groups. Spherical equivalent, cylindrical power and axis were analyzed as a function of age.Results: Spherical equivalents of right and left eyes did not differ at any age. Hyperopia declined significantly with increasing age. The variability in spherical equivalent also decreased significantly with age. Cylindrical error of one diopter or more was found in 15% of children; the proportion with astigmatism was highest in infancy and then waned. Myopia and anisometropia were rare, occurring in 5% and 2% of the sample, respectively.Conclusions: Significant declines in ...
Rimless eyeglasses, are a type of eyeglasses in which the lenses are mounted directly to the bridge and/or temples. The style is divided into two subtypes: three-piece glasses are composed of lenses mounted to a bridge and two separate temple arms, while rimways (also called cortlands) feature a supporting arch that connects the temples to the bridge and provides extra stability for the lenses. Rimless glasses were a popular style of eyeglasses from the 1880s until into the 1960s, and re-emerged in popularity in the latter part of the 20th century and early 21st century. Apple founder, Steve Jobs, began wearing round rimless eyeglasses in 1993 until his death in 2011, an 18 year run. Despite these shifts, they are unique amongst eyeglass styles in that they have never gone completely out of fashion, remaining an acceptable alternative through the years to more stylish designs. Rimless glasses lenses are held in place (or mounted) by way of a series of screws, or hollow plastic double rivets ...
Prescription eyeglasses for sports are almost indispensable to those who indulge in serious sporting activities. People who play sports need to see clearly which is why they have to choose special prescription eyeglasses. Besides allowing you to see clearly, these items of eyewear will also provide protection to your eyes and because such items are impact resistant they also reduce the risk of suffering injuries from broken lenses.. The best part about wearing prescription eyeglasses for sports is that these items will also help you improve your performance and they will prevent injuries. Since these items of eyewear help you to see clearly there is a very low likelihood that you will injure yourself because you could not see things clearly. One should understand that ordinary prescription eyeglasses do not always help you when you wear them while playing sports. It therefore makes sense to invest in a good pair of prescription eyeglasses for sports.. When you step onto a sport field you need to ...
Refractive errors are a common, correctable cause of impaired vision throughout the world.The normal eye creates a clear image by bending (refracting) light to focus onto the retina. Refractive errors occur when a component of the eyes optical syste
Read about hypermetropia and hypermetropi. Find information hypermetropia. Read about myopia. Read on refractive errors. Read about laserbehandling., Treatment Read, read about the symptoms of hypermetropia.
Astigmatism,a type of refractive error, is a common eye condition characterized by an irregular curvature of the cornea and can be treated with glasses.
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Online Doctor Chat - Refractive error in the eyes post prolonged use of TB medicines, Ask a Doctor about diagnosis, treatment and medication for Asthenopia, Online doctor patient chat conversation by Dr. Chakravarthy Mazumdar
Fingerprint Dive into the research topics of Association between time spent on smart devices and change in refractive error: A 1-year prospective observational study among Hong Kong children and adolescents. Together they form a unique fingerprint. ...
PURPOSE: This work investigates how short-term changes in blood glucose concentration affect the refractive components of the diabetic eye in patients with long-term Type 1 and Type 2 diabetes. METHODS: Blood glucose concentration, refractive error components (mean spherical equivalent MSE, J0, J45), central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), axial length (AL) and ocular aberrations were monitored at two-hourly intervals over a 12-hour period in: 20 T1DM patients (mean age ± SD) 38±14 years, baseline HbA1c 8.6±1.9%; 21 T2DM patients (mean age ± SD) 56±11 years, HbA1c 7.5±1.8%; and in 20 control subjects (mean age ± SD) 49±23 years, HbA1c 5.5±0.5%. The refractive and biometric results were compared with the corresponding changes in blood glucose concentration. RESULTS: Blood glucose concentration at different times was found to vary significantly within (p,0.0005) and between groups (p,0.0005). However, the refractive error components ...
Myopic shift occurs most rapidly in the first 1.5 years of life after IOL implantation in infancy, reported David R. Weakley, Jr., MD, and fellow researchers. They were focused on a myopic shift at age 5 after cataract surgery with IOL implantation for infants in the Infant Aphakia Treatment Study. Researchers performed refractions at 1 month and at every 3 months until age 4, and then at 4.25, 4.5, and 5 years of age. Of 43 eyes that were analyzed, the mean rate of myopic direction change from 1 month after surgery to age 1.5 years was 0.35 D; after age 1.5 years, the mean rate of myopic direction change was 0.97 D per year. In children who had surgery at age 1 month and were age 5 at the time of the study, the mean refractive change was 8.97 D. The mean refractive error at age 5 was -2.53 D. If the goal is emmetropia at age 5 years, then the immediate postoperative hypermetropic targets should be +10.5 D at 4 to 6 weeks and +8.50 D from 7 weeks to 6 months, the researchers concluded. ...
More than half of the population wears some form of prescription eyeglasses. Most of these individuals are not aware that wearing eyeglasses poses some risk. The injuries from wearing eyeglasses among elderly patients aged 65 and over resulted from falls. The second highest category of eye related injuries were sports injuries. Not only the physical injuries but also the harm to your vision. For example, if you are myopic, your vision will worsen if you wear glasses because eyeglasses just help you to see clearly as a medical aid, it cannot completely cure your vision loss. So in conclusion, the most important solution is to take eye excise and naturally make your vision better.
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Abstract:. Aim: To find out the prevalence of refractive error in school children and common morbid conditions present amongst them. Material and Methods: It was a cross sectional study. The present study was planned to know the prevalence of refractive in school children in Pune city, and their correlation with socio demographic profile if any. The study was conducted in urban field practice area of a Medical College in Pune. School children of age 6-16 years of selected urban schools in the field practice area were the study population. The sample size calculated was 866 but 1157 were covered in this study. Results: Prevalence of refractory error was 6.22%. Myopia was most common (94.44%) type of refractive errors. Most commonly occur in age group of belonged to 9-11 years, females (52.78%).Only 12(16.67%) were diagnosed early having refractive error other remained undiagnosed /undetected. Amongst them only 33.33% were wearing spectacles Most common reason for not wering spectacles was not ...
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Eye disorders in children are either refractive or nonrefractive errors. Refractive errors are those caused by the shape of the eye. Nonrefractive errors are caused by disease.
Distinct Styles Of Eyeglasses With Advanced Technologies In the world of advance technology, eye vision problems are increasing rapidly. For protecting your precious eyes from harmful rays, healthcare professionals recommend eyeglasses. Nowadays, many national as well as international companies are associated with the manufacturing of spectacles including Ray-Ban, Prada, Gucci that offer eyeglasses with distinct […]. Read the full story. ...
Corneal inlays to correct refractive errors are not new-various materials have been tried for more than 50 years to correct blurred vision. The greatest barriers to success of corneal inlays have been a lack of biocompatibility with the cornea, the difficulty of placing them within the corneal stroma safely, and refractive predictably. ...
If either your cornea or lens is egg shaped with two mismatched curves, light rays arent bent properly, causing a refractive error. This makes a blurry image. Astigmatism is a type of refractive error.. Astigmatism occurs when your cornea or lens is curved more steeply in one direction than in another. You have corneal astigmatism if your cornea has mismatched curves. You have lenticular astigmatism if your lens has mismatched curves.. Either type of astigmatism can cause blurred vision. Blurred vision may occur more in one direction, either horizontally, vertically or diagonally.. Astigmatism may be present from birth, or it may develop after an eye injury, disease or surgery. Astigmatism isnt caused or made worse by reading in poor light, sitting too close to the television or squinting.. ...
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Thus, a person with myopia would have a negative refractive error, a person with emmetropia would have zero refractive error ... Individuals that have parents with certain refractive errors are more likely to have similar refractive errors. The Online ... which will improve vision only in the case of refractive error.[citation needed] The management of refractive error is done ... Refractive error may be quantified as the error of a wavefront arising from a person's far point, compared with a plane, or ...
... the refractive error in the weaker eye was corrected to balance the refractive error of the other eye. Strabismus surgery was ... "Wavefront excimer laser refractive surgery for adults with refractive errors". Cochrane Database Syst Rev. 6 (6): CD012687. doi ... Changes to refractive error occurring during normal age development need to be accounted for, and children have a higher risk ... it is recommended that the refractive surgery be done first. Pediatric refractive surgery involves other risks than refractive ...
Refractive error less than or equal to +2.00 diopters (D). Moderate: Refractive error greater than +2.00 D up to +5.00 D. High ... It is a type of refractive error. Diagnosis is based on an eye exam. Management can occur with eyeglasses, contact lenses, or ... "Facts About Refractive Errors". National Eye Institute. October 2010. Archived from the original on 28 July 2016. Retrieved 30 ... Ramjit, Sihota; Radhika, Tandon (15 July 2015). "Refractive errors of the eye". Parsons' diseases of the eye (22nd ed.). ...
"Prevalence of Refractive Errors". Archived from the original on 2016-03-05. Retrieved 2015-06-05. "Private Public Mix Working ... Prevalence of Refractive Errors in a public school children of Lahore 2. Private Public Mix Working Model of a Teaching ...
... s measure spherical refractive errors. Astigmatism can also be measured using a "clock target" with the device. A ... du Toit R, Soong K, Brian G, Ramke J (August 2006). "Quantification of refractive error: comparison of autorefractor and ... A focometer is an instrument that measures refractive errors and is intended to provide rural or economically disadvantaged ... inexpensive means for measuring refractive error in human vision. The portable, hand-held instrument is highly appropriate for ...
Weale RA (2003). "Epidemiology of refractive errors and presbyopia". Survey of Ophthalmology. 48 (5): 515-43. doi:10.1016/S0039 ... Accumulation of errors: The idea that ageing results from chance events that escape proof reading mechanisms, which gradually ... as each cell division is a chance for errors in DNA replication. Genetic instability: Dogs annually lose approximately 3.3% of ...
In the case of the eye, a large pupil emphasizes refractive error and a small pupil masks it. This phenomenon can cause a ... Other types of refractive error are hyperopia, astigmatism, and presbyopia. Various forms of myopia have been described by ... Because myopia is a refractive error, the physical cause of myopia is comparable to any optical system that is out of focus. ... August 2003). "Refractive error and ethnicity in children". Archives of Ophthalmology. 121 (8): 1141-7. doi:10.1001/archopht. ...
Honavar SG (2019). "The burden of uncorrected refractive error". Indian J Ophthalmol. 67 (5): 577-578. doi:10.4103/ijo.IJO_762_ ...
"Myopia and Refractive errors in Dogs" (PDF). Investigative Optholmology and Visual Science. Association for Research in Vision ... Familial Aggregation of Refractive Error in Labrador Retrievers". Investigative Ophthalmology & Visual Science. 49 (11): 4784- ... In cases involving German Shepherds, Rottweilers and Miniature horses, the refraction errors were indicative of myopia. Nuclear ... laboratory investigations using retinoscopy of 240 dogs found myopic problems with varying degrees of refraction errors ...
These lenses may also correct refractive error. Although many brands of contact lenses are lightly tinted to make them easier ... most commonly by correcting refractive error. This is done by directly focusing light so it enters the eye with the proper ... Soft lenses are often used in the treatment and management of non-refractive disorders of the eye. A bandage contact lens ... He used wax to affix water-filled lenses to his eyes, neutralizing their refractive power, which he corrected with another pair ...
... is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted ... 2003). "Refractive Error and Ethnicity in Children". Archives of Ophthalmology. 121 (8): 1141-7. doi:10.1001/archopht.121.8. ... An autorefractor or retinoscopy may provide an objective estimate of the eye's refractive error and the use of Jackson cross ... They also found that the TOX gene region previously identified for spherical equivalent refractive error was the second most ...
The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such ... This can be used to distinguish visual defects caused by refractive error, which improve when the occluder is used, from other ... Naidoo, Kovin (2002). "Case Finding in the Clinic: Refractive Errors". Comm Eye Health. 15 (43): 39-40. PMC 1705884. PMID ... Because light passes only through the center of the eye's lens, defects in the shape of the lens (errors of refraction) have no ...
Medical professionals characterize refractive errors as consequences of the eye's shape and other basic anatomy, for which no ... The book included accounts of 12 "real cases", but did not report any information about refractive error. Czech native John ... not only to refractive errors, but also to double vision, crossed-eye, lazy eye, and to more serious eye conditions such as ... Visual Training for Refractive Errors". American Academy of Ophthalmology. Archived from the original on 8 January 2016. ...
The inequality of red reflection in both the eyes indicates unequal refraction, indicating a refractive error. Pupil of a ... Congenital cataract, refractive error, ocular alignment, retinal abnormalities. Strabismus, amblyopia or amblyogenic disorder. ...
Causes include: Refractive errors Divergence insufficiency Convergence excess; this can be due to nerve, muscle, congenital or ...
Does cryotherapy affect refractive error? Ophthalmology 108:343-347, 2001. Bleyl SB, Kivlin JD, et al. (2007). "Brachymesomelic ...
Refractive error can be corrected using a pinhole occluder. If the visual acuity improves with the use of pinholes, refractive ... Refractive error can be estimated via photography, a technique called photoscreening. Research has shown that optotype " ... Often, the use of such refractive lenses will correct visual acuity to normal. ...
Goyal, Ashish; Bopardikar, Ajit; Tiwari, Vijay Narayan (2018). "Estimation of Spherical Refractive Errors Using Virtual Reality ...
Refractive errors in patients with FXS are also common. Individuals with FXS are at a higher risk of developing seizures, with ...
A difference in refractive error between the eyes or the presence of astigmatism will not be accounted for. People with little ... These lenses are used when one or both eyes do not require correction of a refractive error. Some people with good natural ... The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" ... Astigmatism of the corrective lens: This phenomenon is called lens-induced oblique astigmatism error (OAE) or power error and ...
"Global cost of correcting vision impairment from uncorrected refractive error". Bulletin of the World Health Organization. 90 ( ... "The global cost of correcting vision impairment from uncorrected refractive error", with findings published in the Bulletin of ...
This can lead to under/overcorrection of the refractive error. In the case of the overcorrection, premature consequences of ... "LASIK Alternatives , UCLA Laser Refractive Center". UCLA Laser Refractive Center. Retrieved 2018-01-29. Zhao, LQ; Zhu, H; Li, ... those receiving PRK were less likely to achieve a refractive error, and were less likely to have an over-correction than ... Uncomplicated, successful corneal refractive surgery does not require a waiver and is noted as information only. The Navy and ...
"Wavefront excimer laser refractive surgery for adults with refractive errors". Cochrane Database Syst Rev. 6 (6): CD012687. doi ... outcomes between conventional excimer laser refractive surgery and wavefront-guided or wavefront-optimized refractive surgery, ...
He has also discovered a new refractive error called Aberropia. He has also been the first to do a combined surgery of ... Agarwal, Amar (1999). Refractive Surgery- First edition. Chennai: Jaypee, Distributed internationally by Slack and Highlights ... He is also the past President of the International Society of Refractive Surgery (ISRS) and Secretary General of the ... "Aberropia: the discovery of a new refractive entity". 1 July 2007. Archived from the ...
Rubin, M.L., Surgical procedures available for influencing refractive error., in Refractive Anomalies of the Eye. 1966, US ... and high refractive errors of at least -5 to -7.5 diopters with an increase per year. There may also be changes in the fundus, ... Bores, L.D., Scleral Reinforcement, in Refractive Eye Surgery. 2001, Blackwell Science, Inc.: USA. p. 466-491. Curtin, B.J., ...
Astigmatism is a condition wherein there occurs significant refractive error. Moreover, ocular albino eyes become crossed, a ...
For an unaccommodated myopic eye, the far point is closer than 6 m. It depends upon the refractive error of the person's eye. ...
Amblyopia: is a category of vision loss or visual impairment that is caused by factors unrelated to refractive errors or ... The most common causes of visual impairment globally in 2010 were: Refractive error (42%) Cataract (33%) Glaucoma (2%) Age- ... The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2 ... This includes cataracts, onchocerciasis, trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some ...
In an eye exam, the term refraction is the determination of the ideal correction of refractive error. Refractive error is an ... Examples of refractive error are myopia, hyperopia, presbyopia and astigmatism. The errors are specified in diopters, in a ... The information bounced back to the instrument gives an objective measurement of refractive error without asking the patients ... Based on the movement and orientation of this retinal reflection, the refractive state of the eye is measured. An auto- ...
... the device provides a quantitative measurement of the refractive error without the need of a physician on the ground. The test ... NETRA allows for the early, low-cost diagnosis of the most common refractive Refractive Disorders. The subject looks into the ... Interactive Display for Estimating Refractive Errors and Focal Range" (PDF). ACM Transactions on Graphics. 29 (4). doi:10.1145/ ... eye diagnostics like NETRA is tremendous and is global in scale-over half a billion people have uncorrected refractive errors. ...
... errors) between desired and calculated properties; Reduction of the sum of square errors using the Solver option in Microsoft ... Glass batch calculation Calculation of the Refractive Index of Glasses Vogel, Werner (1994). Glass chemistry (2nd revised ed ... Systematic errors such as seen in the picture are quantified by dummy variables. Further details and examples are available in ... ISBN 1-57498-225-7. The Mixed-Alkali Effect for the Viscosity of Glasses Overview, Measurement Errors of Glass Properties ...
They compensate for refractive errors (such as presbyopia) by providing variable focusing, allowing users to adjust them for ... The appropriate addition range depends on the user's level of refractive error.[clarification needed] A tiny mechanism, ...
... no error or ambiguity will result. Whichever convention is used, it will always be understood that Pr can never exceed Pi . In ... a loss that takes place at discontinuities of refractive index, especially at an air-glass interface such as a fiber endface. ...
K.L. Bai, J. Katz, On the refractive index of sodium iodide solutions for index matching in PIV, Exp. Fluids 55(4) (2014). S. ... J. Chen, J. Katz, Elimination of peak-locking error in PIV analysis using the correlation mapping method, Measurement Science ... Unobstructed particle image velocimetry measurements within an axial turbo-pump using liquid and blades with matched refractive ...
Because pressure-measurement error can be caused by more than just CCT (such as by corneal hydration or elastic properties), it ... Journal of Cataract and Refractive Surgery. 40 (8): 1301-1306. doi:10.1016/j.jcrs.2014.01.032. PMID 24943904. "Xen Gel Stent". ... Journal of Cataract and Refractive Surgery. 34 (3): 433-440. doi:10.1016/j.jcrs.2007.11.029. PMID 18299068. S2CID 23904366. ... Journal of Cataract and Refractive Surgery. 33 (7): 1217-1226. doi:10.1016/j.jcrs.2007.03.051. PMID 17586378. S2CID 36397585. ...
Prenatal stage Premature Birth Refractive error Congenital cataract Retinopathy of prematurity (ROP) Infection such as ...
A negative refractive index in the optical range was first demonstrated in 2005 by Shalaev et al. (at the telecom wavelength λ ... Wikipedia articles incorporating text from the National Institute of Standards and Technology, CS1 errors: missing periodical, ... PMMs can be made with a gradient index (a material whose refractive index varies progressively across the length or area of the ...
As solutes other than sucrose may affect the refractive index and the specific gravity differently, this refractive "Brix" ... and the Normal-Eichungs Kommission to 6 with the goal of the Commission being to correct errors in the 5th and 6th decimal ... in particular its refractive index and the extent to which it rotates the plane of linearly polarized light. The refractive ... which is based on knowledge of the way the refractive index of sucrose changes. For example, the refractive index of a sucrose ...
... refractive errors,congenital color deficiency and various risk factors that are associated with the conditions https://pubmed. ... Cite error: A tag is missing the closing (see the help page). A new recording of fourteen Rachmaninov songs, a selection of ... Pages with reference errors, Pages with incorrect ref formatting, Articles with topics of unclear notability from September ...
Each used a f/7.9 refractive optical system with a focal length of 150 mm. A frame-transfer charge-coupled device (CCD), a ... The root cause of the event was reported to be a software programming error. To cruise from Earth to its targets, Dawn traveled ... It responded by going into safe mode and sending a signal to engineers, who fixed the error on July 2, 2015. Engineers ...
... s convert a prescription for the correction of a refractive error into an ophthalmic lens or some other device, such as ... since even tiny errors cause eye strain. Pupilometer apps have also been developed for smart phones and tablets. The fitting ...
First of all, the measurement of refractive error may vary from one measurement to the next. Secondly, different criteria have ... Anisometropia is caused by common refractive errors, such as astigmatism, far-sightedness, and myopia, in one eye. ... a condition where even when correcting the refractive error properly, the person's vision in the affected eye is still not ... refraction and refractive errors: control of postnatal eye growth, current and developing treatments", Pediatric Ophthalmology ...
Later analyses showed several errors and incorrect assumptions with this experiment but, serendipitously, these errors canceled ... Lipid bilayers exhibit high levels of birefringence where the refractive index in the plane of the bilayer differs from that ... perpendicular by as much as 0.1 refractive index units. This has been used to characterise the degree of order and disruption ...
... it is susceptible to error. In practice, the error can be as high as 25 percent. The color indicator tubes are well suited for ... A silicon oxide sensor can be an optical device that changes its refractive index as water is absorbed into the sensitive layer ...
Determination of refractive index ISO 281:2007 Rolling bearings - Dynamic load ratings and rating life ISO 282:1992 Conveyor ... Balance errors [Withdrawn: replaced with ISO 21940-14] ISO/R 1941:1970 Flat seal for hydraulic couplings [Withdrawn without ... Determination of the refractive index of the fat (Reference method) ISO 1740:2004 Milkfat products and butter - Determination ... Determination of refractive index ISO 490:1993 Cinematography - Magnetic stripes and magnetic recording head gaps for sound ...
... error free, detection could be obtained. This is done by compressing all energy into an infinitesimal time slice. What limits ... radar beam follows a linear path in vacuum but follows a somewhat curved path in atmosphere due to variation in the refractive ...
... diabetes heart disease hypertension inflammatory bowel disease intellectual disability mood disorder obesity refractive error ... Most congenital metabolic disorders known as inborn errors of metabolism result from single-gene defects. Many such single-gene ... Genetic epidemiology List of genetic disorders Population groups in biomedicine Mendelian error "Genetic Disorders". Learn. ...
He realised that even if light were transmitted as waves the refractive index of the glass-air interface should have varied as ... 125-35; also translated (with several errors) by R.R. Traill as "Letter from Augustin Fresnel to François Arago concerning the ... These predictions arose because the refractive index of a substance such as glass depends on the ratio of the velocities of ... In 1810, François Arago realised that variations in the refractive index of a substance predicted by the corpuscular theory ...
... and refractive visual errors. The nose may be small, wide, and upturned. The development of the ears and auditory system may be ...
ISBN 0-683-30076-8. {{cite book}}: ,author= has generic name (help) v t e v t e (CS1 errors: generic name, Articles with short ... In ophthalmoscopic examination it appears as small, flat, yellow, highly refractive crystals of cholesterol floating freely in ...
There are many causes of blurred vision: Refractive errors: Uncorrected refractive errors like myopia, high hypermetropia, and ... visual blur due to refractive errors can be corrected to normal using corrective lenses or refractive surgeries. Presbyopia due ... ISBN 978-81-312-1132-8. "WHO , Global magnitude of visual impairment caused by uncorrected refractive errors in 2004". WHO. ... Other medical conditions may include refractive errors such as myopia, high hypermetropia, and astigmatism, amblyopia, ...
If we leave the width L fixed in each point, but we change the value of the refractive index n ( x ) {\displaystyle n(x)} we ... In 1991, a Bell Labs research team transmitted solitons error-free at 2.5 gigabits over more than 14,000 kilometres, using ... Now let us assume we have a medium that shows only nonlinear Kerr effect but its refractive index does not depend on frequency ... It is because generated impulses have a non-zero bandwidth and the medium they are propagating through has a refractive index ...
CS1 errors: missing periodical, CS1 errors: generic name, CS1 maint: DOI inactive as of September 2022, CS1 maint: multiple ... It has one of the lowest refractive indexes and the furthest transmission range in the deep UV of most common materials. Finely ... names: authors list, CS1 maint: uses authors parameter, CS1: long volume value, CS1 errors: missing title, CS1 errors: bare URL ...
The errors in these approximations, which were obtained empirically, are of order h 3 {\displaystyle h^{3}} and h 5 , {\ ... In a material that is optically anisotropic (birefringent), the refractive index depends on the direction of the light. The ...
If the shape of the cornea is fairly regular and refractive error is similar to that of the other eye, it is usually possible ... A few months after the stitches are removed, measurements are made of the shape of the cornea and refractive error. ... to fix any error with glasses; if not, a hard lens may be necessary to correct vision. One of the largest causes for issue in ...
Refractive and reflective optical properties can be tabulated as a function of wavelength, to approximate system performances; ... By superimposing a reference beam with the beam reflected from the surface to be measured, error maps, known as interferograms ... tolerances and errors can also be evaluated. In addition to focal integrity, aspheric lens systems can be tested for ... form of asphere surface form deviation slope error centre thickness roughness A distinction is made between tactile, i.e. ...
This is due in large part to advances in optometry which allow for better measurement of refractive error, so that glasses and ...
The refractive index of ice Ih is 1.31. The accepted crystal structure of ordinary ice was first proposed by Linus Pauling in ... CS1 errors: missing periodical, CS1 maint: multiple names: authors list, Articles with short description, Short description is ...
Here considering only refractive caustic, the objective can be determined as follows (similar principle for reflective caustic ... mean square error of the rendered image and the target c: contains elements which can influence the generated image I: target ... Common refractive materials: acrylic, polycarbonate, polyethylene, glass, diamond Common reflective materials: steel, iron, ...
Thats a refractive error, caused by an irregular-shaped cornea or lens. Learn how its treated. ... Refractive errors are vision problems that happen when the shape of the eye keeps you from focusing well. The cause could be ... Refractive Errors in Children (American Association for Pediatric Ophthalmology and Strabismus) * Treatment of Increasing ... Article: Prevalence of refractive error in Portugal estimated from ophthalmic lens manufacturing... ...
Prevalence of refractive error and low vision among schoolchildren in Cairo  El Bayoumy, B.M.; Saad, A.; Choudhury, A.H. (‎ ... A preliminary survey was conducted to detect the prevalence of refractive error [‎RE]‎ and low vision among 5839 schoolchildren ... This study evaluated the preventable environmental risk factors of refractive error [‎RE]‎ among 1292 Egyptian schoolchildren ... Browsing EMRO Journal Articles (‎EMHJ)‎ by Subject "Refractive Errors". 0-9. A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q ...
Refractive errors are some of the most common vision problems people experience. ... A refractive error is something about the natural shape of your eyes that makes your vision blurry. ... Many refractive errors first appear in kids. But you can develop a refractive error at any point in your life, even if youve ... What causes refractive errors?. Changes in the shape of your cornea, your lens or your whole eye can cause refractive errors. ...
Prevalence of refractive error and low vision among schoolchildren in Cairo  El Bayoumy, B.M.; Saad, A.; Choudhury, A.H. (‎ ... Elimination of avoidable visual disability due to refractive errors : report of an informal planning meeting, Geneva, 3-5 July ... A preliminary survey was conducted to detect the prevalence of refractive error [‎RE]‎ and low vision among 5839 schoolchildren ... This study evaluated the preventable environmental risk factors of refractive error [‎RE]‎ among 1292 Egyptian schoolchildren ...
... had their refractive error corrected with contact lenses where the mean refractive error measured -3.12D. Each participant was ... The refractive error was measured using cycloplegic autorefraction over a two year period. A causative link between peripheral ... Visual acuity results improved in both treatment groups (P,0.05); the control group was unchanged for VA and refractive error. ... Rosen RC, Schiffman HR, Meyers H. Behavioral treatment of myopia: refractive error and acuity changes in relation to axial ...
Diabetic macular edema patients have minimal changes in refractive error. The correction of refractive error may be considered ... REFRACTIVE ERROR CHANGE DURING TREATMENT OF DIABETIC MACULAR EDEMA. A Post Hoc Analysis of the Diabetic Retinopathy Clinical ... REFRACTIVE ERROR CHANGE DURING TREATMENT OF DIABETIC MACULAR EDEMA: A Post Hoc Analysis of the Diabetic Retinopathy Clinical ... REFRACTIVE ERROR CHANGE DURING TREATMENT OF DIABETIC MACULAR EDEMA: A Post Hoc Analysis of the Diabetic Retinopathy Clinical ...
Refractive error that is not diagnosed or treated is called uncorrected refractive error (URE). Uncorrected refractive error is ... Table 1. Uncorrected Refractive Error Prevalence Sources.. Uncorrected Refractive Error Prevalence Sources. Author. Date of ... Overall Refractive Error Prevalence Rates. Figure 1 below shows estimated prevalence rates for uncorrected refractive error ( ... The Prevalence and Risk Indicators of Uncorrected Refractive Error and Unmet Refractive Need in Latinos: the Los Angeles Latino ...
... are caused when the shape of the eye, length of the eyeball or similar issues do not allow light to focus ... World Health Organization: Blindness and vision impairment: Refractive errors * American Academy of Ophthalmology: Refractive ... Anyone can have refractive errors, but youre at higher risk if you have family members who wear glasses or contact lenses. ... Most types of refractive errors, like nearsightedness, usually start in childhood. Presbyopia is common in adults ages 45 and ...
Refractive errors and school performance in Brazzaville, Congo * P.W. Atipo-Tsiba ... Conclusion: Refractive errors largely determines pupil performance in schools in Brazzaville, Congo. The routine use of glasses ... Objective: To determine the role of refractive errors in school performance in Brazzaville. ...
The Regional Planning Course on Refractive Errors and Low Vision will be conducted from 19-25 November 2007 in the Regional ... Course on Refractive Errors and Low Vision will be held in the WHO ... Correcting refractive errors is so simple; however it has yet received little government or NGOs attention and has been easily ... Media centre , News , Press archive , 2007 , Course on Refractive Errors and Low Vision will be held in the WHO ...
B) Distribution of refractive error in children at 11 years old or less and their parents. (C) Distribution of refractive error ... Preoperative refractive error was used in 13 parents who had previously undergone refractive surgery. Besides refractive ... only the childrens non-cycloplegic refractive error, and the parents and grandparents binary refractive error state (myopia or ... of the parental refractive error was obtained through self-reporting. However, analysis for RED with both parents refractive ...
... this is possibly a refractive error in your eyes. Refractive errors are surprisingly common, affecting a considerable amount of ... Refractive errors of the eye. Posted on March 9, 2020. May 13, 2021. by Dr. Chukwudi Ekomaru , 2 min read ... A refractive error is an eye disorder which results in the inability of the eye to clearly focus on objects, resulting in ... In individuals without refractive errors, the lens is elastic and alters its shape to increase its power, bringing visible ...
653T,653Z,Apel,astigmatism,enhancement,Gatzioufas,McKelvie,McLintock,piggyback,pseudophakic,refractive,refractive error, ... Home , Eye Science , Outcomes of toric supplementary intraocular lenses for residual astigmatic refractive error in ... Outcomes of toric supplementary intraocular lenses for residual astigmatic refractive error in pseudophakic eyes. Posted on 1/ ...
Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of ... Our results support the notion that refractive errors are caused by a light-dependent retina-to-sclera signaling cascade and ... Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error. Publication. ... Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error. Nature Genetics, 1- ...
... for diagnosing refractive errors in children. Methods 123 school-age children (9.9 ± 3.3 years) with moderate refractive error ... were used to evaluate the performance of the device in measuring refractive error. Results The spherical equivalent refraction ...
... clearly indicated that detailed comparisons of refractive error prevalence across study reports are generally not possible ... Case finding for refractive errors: assessment of refractive error and visual impairment in children. Leon B Ellwein PhD. ... Refractive error in this age group was usually due to myopia with a relatively high prevalence among Chinese children (Figure 3 ... Refractive error study in children: sampling and measurement methods for a multi-country survey. Am J Ophthalmol 2000; 129: 421 ...
Internal Compensation of Lateral Coma Aberration: Relationship to Refractive Error You will receive an email whenever this ... N.J. Coletta, H. Han, A. Moskowitz; Internal Compensation of Lateral Coma Aberration: Relationship to Refractive Error . Invest ... We examined the roles of pupil displacement and refractive error in the amount of corneal and ocular lateral coma aberration. ... values were smaller than the corneal values and did not vary significantly with either pupil displacement or refractive error. ...
Refractive errors are extremely common and they affect the ability of the eyes to focus light properly on the retina, at the ... What are refractive errors? Refractive errors are extremely common and they affect the ability of the eyes to focus light ... A refractive error can cause a number of symptoms. Some of them are harder to identify, especially when the refractive error ... Genetics can play a huge role when it comes to refractive errors. If you have family members who have refractive errors, you ...
"Refractive Errors" by people in this website by year, and whether "Refractive Errors" was a major or minor topic of these ... "Refractive Errors" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... Unequal refractive error and high astigmatism associated with orbital lymphangioma. Mil Med. 1993 Jun; 158(6):429-31. ... Below are the most recent publications written about "Refractive Errors" by people in Profiles. ...
Prevalence rates of refractive errors in Sumatra, Indonesia. Authors: Saw, S.-M. Gazzard, G.. Koh, D. Farook, M.. Widjaja, D.. ... Saw, S.-M.,Gazzard, G.,Koh, D.,Farook, M.,Widjaja, D.,Lee, J.,Tan, D.T.H. (2002-10). Prevalence rates of refractive errors in ... Refractive error measurements were obtained with one of two handheld autorefractors. Household interviews were conducted to ... The prevalence rate of high myopia is lower than in most other populations, and other refractive errors are common. ...
CRT outdoors Pathology and eye health Pharmaceuticals Pre-Myope Progressive Lenses Refraction refractive error Risk factors ...
Tag: refractive error. Visual Disabilities and Impairment: Mostly Refractive, Mostly Preventable. by DrB • July 31, 2017. • 0 ...
... by addressing Uncorrected Refractive Error (URE) in Mozambique and the wider region of sub-Saharan Africa by providing ... The cost of refractive services must be addressed if the burden of URE is to be reduced. While the average WTP value lies ... The average amount in USD participants would be willing to pay for refractive services was US$12 for stated choice and US$15 ... Thompson, S. J. (2014).The Social and Economic Impact of Refractive Error in Mozambique.Doctoral Thesis.Technological ...
The refractive errors of the students eyes were measured using non-cycloplegic autorefraction. ... Prevalence of refractive conditions in Singapore teenagers. Grade 9 and 10 students (n = 946) aged 15-19 years from two ...
... PubMed, SCI, Scopus, ESCI, ... This is how NGOs, instead of States, are called upon to assume the leading role in the management of refractive errors at the ... Background: Uncorrected refractive errors (URE) are a serious public health problem by their magnitude, the multiple ... McCarty CA, "Uncorrected refractive error," British Journal of Ophthalmology, vol. 90, no. 5. BMJ Publishing Group 90 (2006). ...
Visual Function After Correction of Distance Refractive Error with Ready-Made and Custom Spectacles: A Randomized Clinical ...
HONG, CHEN AI (2000) Effect of the body posture on visual acuity, refractive error and binocular vision. UNSPECIFIED. ... Effect of the body posture on visual acuity, refractive error and binocular vision. ...
There are several types of refractive surgeries, but the most popular are:. *Refractive lensectomy, also called refractive lens ... Refractive Errors (Vision Problems). Overview. We must have light in order to see. Most common vision problems are caused by ... Your eye doctor will determine the type and degree of refractive error you have by performing a test called refraction. This ... Eyeglasses are the simplest and safest way to correct refractive errors. Eyeglass lenses are designed with precise curves to ...
The shape of your cornea is responsible for the majority of your eyes refractive power. ... it is usually because there is a refractive error present. Any eye with a refractive error is considered to be ametropic. ... Common refractive errors. Your ability to refract light correctly depends on four key characteristics that can often change ... Laser Eye Surgery can correct refractive errors by removing a pre-determined amount of cells from the cornea, which is located ...
AIM: To study the distribution of refractive error in different ethnic groups of Nepal. METHODS: A total of 1276 new eye ... Karki KJ, Karki M. Refractive error profile--a clinical study. Kathmandu University Medical Journal. 2004 Jul-Sep; 2(3): 208-12 ... The ethnic distribution of refractive error shows that there are 32.44% Newars; 27.50% Brahmins; 21.63% Chhetriyas; 12.14% ... CONCLUSION: Thus, a refractive error profile is drawn up in Nepalese population. ...
  • There are four different types of refractive error (RE): myopia, hyperopia, astigmatism, and presbyopia. (
  • Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of blindness. (
  • Refractive error in this age group was usually due to myopia with a relatively high prevalence among Chinese children (Figure 3). (
  • The prevalence rate of high myopia is lower than in most other populations, and other refractive errors are common. (
  • Astigmatism may occur with other refractive errors such as myopia (nearsightedness) and hyperopia (farsightedness). (
  • 1 Vision impairment has been defined based on distance visual acuity only, and uncorrected distance refractive error (mainly myopia) is the single biggest cause of worldwide vision impairment. (
  • Myopia (nearsightedness), hyperopia (farsightedness), presbyopia , and astigmatism are just some samples of refractive errors. (
  • Lasers can be used to carefully reshape the cornea of the eye - the transparent front part of the eye that covers the iris, pupil, and anterior chamber - to correct refractive errors that cause conditions like short-sightedness (myopia), long-sightedness (presbyopia), or blurred vision (astigmatism). (
  • A 2015 report of the joint World Health Organization and Brien Holden Vision Institute Global Scientific Meeting on Myopia defines myopia as the presence of ocular refractive error of ≤ -0.50 diopter and high myopia as the presence of ocular refractive error of ≤ -5.00 diopter. (
  • Significant Refractive Errors Severe myopia (greater than or equal to -6 D), severe hyperopia (greater than or equal to +5.25 D), or prior LVC (LASIK, SMILE or PRK) that corrected for the aforementioned refractive error, excluding those with an AREDS grade of 1 to 4 or a LOCS III grade of 2 to 6. (
  • Refractive defects include myopia, hypermetropia, and astigmatism which generally occurs due to refractive errors leading to vision defects. (
  • They are used to compensate mild refractive errors in patients with myopia , hyperopia and astigmatism . (
  • Refractive errors such as myopia, hyperopia, and astigmatism are currently the most common eye problems. (
  • Myopia, also known as nearsightedness, is a common type of refractive error where close objects appear clear, but distant objects appear blurry. (
  • Children benefit from wearing contact lenses more than just having refractive error correction and myopia control, they have a better self-esteem and improved quality of life. (
  • Myopia is a refractive error that happens when the eye focuses incoming light in front of the retina, rather than directly on it, resulting in blurred distance vision. (
  • Depending on which type of refractive error you have, something about the shape of your eyeball, your cornea or your lens prevents your eyes from focusing correctly on objects you're looking at. (
  • Changes in the shape of your cornea, your lens or your whole eye can cause refractive errors. (
  • Refractive disorders are usually the result of an eyeball that is too short or too long, a cornea (the clear front part of your eye) that is irregularly shaped or a lens that is curved too much or too little. (
  • Refractive surgery permanently changes the shape of the cornea. (
  • PRK refractive uses a laser to reshape the surface layer of your cornea to correct the focus of light rays on your retina. (
  • Laser Eye Surgery can correct refractive errors by removing a pre-determined amount of cells from the cornea, which is located at the front of the eye and is responsible for the majority of your eye's refractive power. (
  • The cornea is designed to work with light passing from the air, which has a refractive index of 1.00. (
  • If the eye doesn't have enough refractive power because it is too short or the surface of the cornea is too flat, light lands beyond the retina to create a distorted image. (
  • For some people, a problem with the shape of the cornea (the eye's transparent outer layer) causes refractive errors. (
  • Some types of surgery, like laser eye surgery, change the shape of your cornea to fix refractive errors. (
  • By specifically removing tissue from different portions of the cornea, the surgeon is able to correct the different refractive errors. (
  • Another method for correcting astigmatism is by changing the shape of the cornea through refractive or laser eye surgery. (
  • Refractive errors happen when there is a change in length of the eyeball, a change in the shape of the cornea, or as a result of an aging lens. (
  • The vision examination is designed to test distance vision in sample persons (SPs) aged 12 years and older, measure refractive error, measure the shape of the cornea and, if applicable, measure the distance eyeglass prescription in SP's aged 12 years and older. (
  • If the cornea or lens is not perfectly round or smooth, an error may occur in the refraction of light as it will cause the light to bend unnaturally causing blurry vision. (
  • Dr David Gunn is a Cornea, Cataract and Refractive Surgeon based in Brisbane. (
  • Dr Gunn specialises in medical and surgical diseases of the cornea, routine and complex cataract surgery and laser and refractive eye surgery. (
  • A lens is a simple medical device to correct focal power and, refractive errors occurring in the cornea of an eye. (
  • Contact lenses may be recommended as they can sometimes improve the acuities of some students with irregular cornea surfaces or with high refractive errors. (
  • Unequal refractive error and high astigmatism associated with orbital lymphangioma. (
  • Astigmatism can be corrected with glasses, contacts or with refractive surgery. (
  • ASTIGMATISM (cylindrical error) occurs when incoming light rays unable to reach a common focus within the eye. (
  • Preoperative measurements seem to be the main source of error for our toric intraocular lens (t-IOL) calculations,' confessed Dr Nino D. Hirnschall [VIROS (Vienna Institute for Research in Ocular Surgery), Hanusch Hospital, Vienna, Austria] during the 'Assessment of Astigmatism' session, which took place on the first day of this year's ESCRS meeting. (
  • Of course, you don't actually know what that error is, but we used a difference vector between the keratometry and the topography and then we used a regression model to predict the remianing astigmatism after surgery. (
  • Eyeglasses and contact lenses are valuable vision aids that allow people with refractive errors such as nearsightedness, farsightedness, astigmatism, etc. to see clearly and comfortably. (
  • Most types of refractive errors, like nearsightedness, usually start in childhood. (
  • Almost all cases of nearsightedness can be corrected with a concave lens or with one of several types of refractive surgery. (
  • Refractive lensectomy, also called refractive lens exchange, corrects nearsightedness or farsightedness. (
  • Talk to your eye care specialist about vision correction surgery if you have a refractive error but don't want to wear corrective lenses. (
  • Uncorrected refractive error is often defined as presenting visual acuity (VA) of 20/50 or worse, and best corrected VA of 20/40 or better, indicating that normal acuity may be achieved through refraction correction. (
  • The prevalence of visual impairment with best refractive correction represents the degree of vision loss attributable to causes other than refractive error. (
  • The use of the EXCIMER LASER in corneal refractive surgery has greatly increased the safety of the procedure as the refractive correction is achieved by the removal of a little as 10 to 20% of the total corneal thickness. (
  • An eye vision correction surgery is required in case you need a permanent solution against the refractive errors. (
  • Children who need vision correction because of refractive errors should have annual eye exams throughout their school years to evaluate any changes. (
  • An excess of false positives can overload referral sites, lead to unnecessary expenditure by patients and reduce confidence in the system, whereas an excess of false negatives means patients will not get the refractive error correction they need. (
  • Clear lens extraction for the correction of high refractive error. (
  • Extrapolating these findings to the general US population, approximately 14 million individuals aged 12 years or older have visual impairment (defined as distance visual acuity of 20/50 or worse), and of these, more than 11 million individuals could have their vision improved to 20/40 or better with refractive correction. (
  • Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life. (
  • Eyes drops filled with synthetic nanoparticules have shown promising potential for a revolutionary alternative non-invasive correction of refractive errors," the authors reported in their study abstract, which analyzed the refractive errors of 10 pig eyes before and after the introduction of the nanodrops. (
  • Refractive error and vision correction in a general sports-playing population. (
  • Now the laser is FDA-approved for topography-guided laser vision correction as well, incorporating refractive error of the eye and corneal irregularities into custom laser ablations. (
  • Typically used for vision correction, glasses come in many types and are classified by their primary function such as correcting refractive errors, magnification, sun protection and safety. (
  • If you have refractive errors before middle age, you can also develop presbyopia on top of your other condition when you get older. (
  • The cost to train refractionists and maintain refractive services to deal with uncorrected refractive error (including presbyopia) is US $28 billion. (
  • This study aimed to determine the prevalence of REs among adults aged ≥30 years in India and the need for refractive services through estimates of the prevalence of URE and uncorrected presbyopia. (
  • If you're older than 40, you may have experienced one of the "joys" of aging: Our eyes change as we get older, inevitably developing a new refractive error called presbyopia. (
  • Refractive error is diagnosed through visual acuity testing, refraction, or a comprehensive eye examination. (
  • Refractive errors are diagnosed by visual acuity and refraction screening tests which are usually accompanied by a comprehensive clinical examination of the eye. (
  • Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus. (
  • Uncorrected refraction errors (URE) are a severe public health problem in view of their magnitude and also by the multiple consequences they cause around the world. (
  • Your eye doctor will determine the type and degree of refractive error you have by performing a test called refraction. (
  • They then compared the predicted refraction with objective refractive outcomes 1 week, 1 month, and 3 months after surgery. (
  • Additionally, all SPs will be administered two other tests which require automated vision equipment: a Visual Acuity test, which tests for distance vision, and an Objective Refraction/Keratometric evaluation, which measures the SP's refractive error and corneal curvature. (
  • To meet the need for guidance in this area, the IAPB Refractive Error Working Group recently published a paper ( ) which defines minimum criteria and recommendations for the quality and operating environment of screening, self-refraction, and self-prescribing devices. (
  • Visual impairment due to uncorrected refractive error was defined as (presenting) visual impairment that improved, aided by automated refraction results, to 20/40 or better in the better-seeing eye. (
  • The degree of refraction ( refractive index) by a medium of the wavelength is dependent of the on the incident light's dispersion. (
  • According to the World Health Organization, an estimated 153 million people live with visual impairment due to uncorrected refractive errors. (
  • The course aims at building the capacity of the national programs in tackling the burden of visual impairment that caused by low vision and refractive errors. (
  • Refractive errors such as short or long sightedness are the greatest cause of avoidable visual impairment among children. (
  • The global strategy of VISION 2020 focuses on visual impairment as a major public health problem and addresses its main causes including refractive errors and low vision. (
  • An exception to this difficulty is a series of population-based surveys of refractive error and associated visual impairment in school-age children conducted in five different geographic regions using a common protocol -the Refractive Error Survey in Children (RESC). (
  • Although some of the refractive error underlying clinically significant visual impairment was found to have been already corrected with spectacles, an essentially equal amount of correctable refractive error remained uncorrected (Figure 2). (
  • Although the relationship between uncorrected visual acuity and refractive error was not a precise one, among those with a relatively high prevalence of visual impairment, correspondingly high amounts of refractive error were found, as expected. (
  • The purpose of this thesis is to investigate potential key determinants of the success, or otherwise, of endeavours to address avoidable Visual Impairment (VI) by addressing Uncorrected Refractive Error (URE) in Mozambique and the wider region of sub-Saharan Africa by providing optometric services. (
  • Indeed, several studies have established the link between quality of life and visual impairment caused by refractive errors [4-11]. (
  • Visual impairment due to uncorrected refractive error is a common condition in the United States. (
  • What Is Refractive Surgery? (
  • Dhaliwal, 2015) Refractive error can be treated with corrective eye glasses, contact lenses, and refractive surgery. (
  • Predictive value of slitlamp examinations in screening donor corneas for prior refractive surgery. (
  • Farsightedness is treated with a convex lens or with refractive surgery. (
  • Refractive errors can also be treated with contact lenses or refractive surgery such as laser surgery. (
  • Laser eye surgery is a simple corrective procedure to treat all kinds of refractive errors. (
  • In these cases, we may offer refractive lens exchange (lens replacement surgery). (
  • A Refractive Secondary Lens Implant is for people who've had cataract or lens replacement surgery and still need glasses. (
  • Refractive Surgery -It is also an option to correct or improve your vision. (
  • Are you an ideal candidate for corneal refractive surgery? (
  • What is the best way to predict pseudophakic refractive error in patients who are about to undergo cataract surgery? (
  • A variety of refractive surgery techniques, which reshape the corneal stroma using laser energy, have been marketed as simple and safe alternatives to glasses or contact lenses. (
  • Although there are few high-quality prospective studies of long-term outcomes, complications, or stability for refractive surgery procedures, there is at least general agreement that more than 90% of appropriately selected patients achieve excellent uncorrected distance vision. (
  • Over the past two decades, a variety of refractive surgery techniques have been developed and marketed as simple and safe alternatives to glasses or contact lenses. (
  • Its popularity in this country has decreased from a peak of 1,400,000 procedures in 2006 for reasons that are not entirely clear, although millions of persons worldwide, particularly in Asia, still choose refractive surgery. (
  • There are few high-quality prospective studies of refractive surgery. (
  • Overall, there is general agreement that refractive surgery is safe and effective. (
  • Most studies reporting on subjective complaints lack objective data concerning persistently bothersome symptoms, and cannot distinguish between refractive error remaining after surgery and adverse effects of the surgery itself. (
  • While there is more than one type of refractive surgery, specific treatments are recommended on an individual basis. (
  • As technology progresses, it is becoming more and more important that you explore all options and possibilities before deciding which refractive surgery and treatment is right for you. (
  • Refractive surgery has entered the mainstream of general ophthalmology, with patients inquiring every day about their potential for the surgery or questioning the results of previous procedures. (
  • Now you have at your fingertips the first concise, easily accessible guide to modern refractive surgery, covering all major surgical procedures and offering expert clinical recommendations on when and how to use them. (
  • Written by highly experienced specialists, the book is designed for all members of the refractive surgery team, with the goal of turning to it for quick reference and confirmation of a diagnosis in every examining room! (
  • If you want a faster and more permanent solution, you may opt to have a refractive surgery such as LASIK . (
  • For these people, sight can be restored with appropriate spectacles, contact lenses, or refractive surgery. (
  • While Dr. Barnes spoke about "refractive surgery", his testimony in the context of a special hearing on LASIK implied that his arguments were in support of the LASIK procedure. (
  • Indeed, the Summary Minutes of the FDA hearing state that, "Dr. Barnes of the Warfighter Refractive Eye Surgery Program emphasized the importance of LASIK to the military. (
  • LASIK surgery, also known as Laser-assisted in situ keratomileuses, is the option to correct the refractive errors. (
  • Refractive services include Lasik surgery which is a tried and tested method for refractive errors. (
  • Latest surgical options and procedures to correct refractive errors by refractive Lasik eye surgery in Bangalore. (
  • LASIK Eye Surgery LASIK eye surgery is an eye surgical procedure that remedies the refractive error of the eye. (
  • Changes in refractive error due to surgery were computed by the ordinary rules of vector subtraction. (
  • Results: Frequency distributions of blur strength (B) clearly demonstrate the effectiveness of refractive surgery at reducing the overall blurring effect of uncorrected refractive error. (
  • For practical reasons, the general principles of excimer laser refractive surgery, which were ex-plained in the first report, are explained again in Appendix A. Also, a brief summary of ocular anatomy and the main refractive errors is repro-duced in the following section to make this re-port easier to understand by readers who might be less familiar with ophthalmology. (
  • The present report provides an update on refractive surgery since the publication of the 1997 report. (
  • Glasses or contact lenses can usually correct refractive errors. (
  • Anyone can have refractive errors, but you're at higher risk if you have family members who wear glasses or contact lenses. (
  • Correcting refractive errors is often easy to do with glasses or contact lenses. (
  • The best way to treat or correct refractive error is through the use of prescription glasses or contact lenses. (
  • The VEHSS team conducted a review of published literature on examination-based population studies reporting the prevalence of uncorrected refractive error. (
  • There were 10 studies published between 2005 and 2016 that examined the prevalence of uncorrected refractive error. (
  • Objective: The objective of this study was to determine the prevalence of uncorrected refractive error among students in three selected secondary schools in Birnin Kebbi metropolis as many children with poor vision due to refractive error remain undiagnosed and perform poorly in schools. (
  • Refractive disorders are usually detected through the tests administered in a routine eye exam. (
  • It's important to schedule an annual eye exam to diagnose and correct refractive disorders. (
  • In children, refractive errors are the most common vision disorders, occurring in 20 percent by 16 years of age. (
  • Refractive error that is not diagnosed or treated is called uncorrected refractive error (URE). (
  • When the delicate mechanics of the eye's optical elements fall out of balance, this leads to refractive error, also known as ametropia. (
  • The difference between presenting and uncorrected vision reflects the amount of refractive error that is already corrected, while the difference between presenting and best corrected vision indicates the extent to which uncorrected refractive error remains as a vision disabling problem. (
  • and the data do not correlate with the situation in optometric uncorrected refractive error remains one of the main education in the EMR ( 13 ). (
  • Most people with refractive errors develop them over time as they grow and develop. (
  • Uncorrected distance refractive error is the biggest single cause of vision impairment worldwide. (
  • From research it was estimated that the number of people with vision impairment due to uncorrected distance refractive error was 107.8 million, 1 and the number of people affected by uncorrected near refractive error was 517 million, 2 giving a total of 624.8 million people. (
  • Uncorrected distance refractive error leading to vision impairment can reduce quality of life 4 and decrease participation in daily activities that are vision-related. (
  • The potential lost productivity as a result of uncorrected distance refractive error is US $268.8 billion per year. (
  • IMSEAR at SEARO: Intraocular pressure dynamics in different refractive errors. (
  • What are the symptoms of a refractive error? (
  • What are symptoms of refractive errors? (
  • A refractive error can cause a number of symptoms. (
  • Go to Refractive error symptoms on this page for more about these. (
  • Many eye conditions produce symptoms right away, but problems with refractive errors can be subtle at first. (
  • Even if your child exhibits no symptoms of a refractive error or other preschool vision problems, he should have an eye exam by the age of 6 months, again at age 3 years, and also prior to starting school. (
  • Refractive errors may happen when the length of the eyeball grows too short or too long. (
  • Expression experiments and comprehensive in silico analyses identified retinal cell physiology and light processing as prominent mechanisms, and also identified functional contributions to refractive-error development in all cell types of the neurosensory retina, retinal pigment epithelium, vascular endothelium and extracellular matrix. (
  • Refractive errors are extremely common and they affect the ability of the eyes to focus light properly on the retina, at the back of the eyeball. (
  • However, when there is a refractive error, the rays of light might be unable to meet at the retina. (
  • Most common vision problems are caused by refractive errors - the eye's inability to focus, or refract, light correctly on the retina (the light-sensitive layer of tissue at the back of the eye). (
  • When the eye cannot focus light on the retina to create a sharp image then it results in a refractive error. (
  • Refractive Error is an eye disorder that results in hazy vision when the shape of your eye keeps light from focusing correctly on your retina. (
  • Refractive error occurs if the eye cannot focus light properly on the retina. (
  • The most common vision problems are refractive errors, which is when the shape of the eye prevents light from directly focusing on the retina. (
  • Refractive errors occur when light does not correctly focus on the retina, which is the light-sensitive tissue at the back of the eye. (
  • Refractive errors occur when there is no image formation on the retina. (
  • Power vectors also provide a natural link to a more comprehensive optical description of ocular refractive imperfections in terms of wavefront aberration functions and their description by Zernike polynomials. (
  • A review of the 28,000 procedures has shown that soldiers with PRK or LASEK have a 20% greater chance of achieving an uncorrected visual acuity of 20/15 or better than soldiers with a similar level of refractive error undergoing LASIK. (
  • 3. PRELEX (presbyopic refractive lens exchange) or clear lens extraction. (
  • A refractive error is an eye disorder which results in the inability of the eye to clearly focus on objects, resulting in blurry vision. (
  • Blurry vision, either up close or at a distance, is the most common sign of a refractive disorder. (
  • En Algérie, le premier cas a été identifié le 25 février 2020, un plan de riposte national élaboré par le ministère de la santé a été mis en place pour affronter l'épidémie. (
  • Refractive error occurs when the eye cannot clearly focus on images, resulting in blurred vision 1 . (
  • This eye condition occurs when vision in one eye is reduced because of a communication error between the brain and the affected eye. (
  • We work with local partners in South Asia and Africa to bring diagnosis and optical services to people with refractive error, at little or no cost to them. (
  • Wallace H, Misra S, Li S, McKelvie J. Predicting pseudophakic refractive error: Interplay of biometry prediction error, anterior chamber depth, and changes in corneal curvature. (
  • By utilizing this imaging technique, ophthalmologists and optometrists can detect even the slightest imperfections in a patient's corneal shape or curvature, which cause refractive errors. (
  • 2003. Decelopment of refractive error and strabismus in children with Down syndrome. (
  • Squint (Strabismus) is a condition which arises due to an incorrect balance of muscles, refractive errors, nerve palsy, and several other reasons. (
  • Refractive errors are extremely common eye conditions that make your vision blurry. (
  • Refractive errors are some of the most common vision problems people experience. (
  • Refractive errors are surprisingly common, affecting a considerable amount of the population, so let's take a closer look. (
  • Refractive errors are one of the most common issues that a person can experience with their vision. (
  • Refractive error conditions are common, so it's important to get eye examinations every two years. (
  • Refractive errors are the most common cause of eyesight problems according to the National Eye Institute. (
  • Refractive error (RE) is one of the most common ocular conditions affecting all age groups. (
  • Effect of the body posture on visual acuity, refractive error and binocular vision. (
  • And every single one of us will develop a vision problem, including refractive error [which makes it hard to see clearly] and cataracts, if we live long enough. (
  • A refractive error is something about the natural shape of your eyes that makes your vision blurry. (
  • Investigators calculated optimum intraocular lens (IOL) power and predicted refractive outcomes using the Barrett Universal II, Hill-RBF, and SRK/T formulas. (
  • Designed for patients with higher degrees of refractive errors, the Implantable Collamer® Lens, or ICL™, was designed to be placed within an eye, overlying the eye's natural lens. (
  • From refractive error to dashed career opportunities, Kim Thomas discusses the lifelong consequences of amblyopia. (
  • Despite being one of the more easily corrected conditions resulting in vision impairment, uncorrected refractive error still remains a significant cause of vision impairment globally. (
  • Refractive errors largely determines pupil performance in schools in Brazzaville, Congo. (
  • We examined the roles of pupil displacement and refractive error in the amount of corneal and ocular lateral coma aberration. (
  • Ocular lateral coma values were smaller than the corneal values and did not vary significantly with either pupil displacement or refractive error. (
  • The influence on unaided vision of age, pupil diameter and spherocylindrical refractive error. (
  • In some cases, refractive services are provided, but an inadequate supply of spectacles makes these services irrelevant as people still have to live with uncorrected refractive error. (
  • In this study, subjects (eyes) will be recruited and divided into 4 groups, i.e. normal, cataract, significant refractive errors and retinal diseases. (
  • Operation Eyesight is also a proud member of the International Agency for the Prevention of Blindness's Refractive Error Coalition . (
  • The ICL lens works with the natural eye lens for correcting refractive errors. (
  • Refractive surgeries require healthy eyes that are free from retinal problems, corneal scars, and any eye disease. (
  • There is a large market for visual training programs as ~150 million U.S. residents currently use some form of eyewear to correct refractive error. (
  • Eyeglasses are the simplest and safest way to correct refractive errors. (
  • 48. Bi-focal lens is used to correct ____________ refractive error. (
  • To evaluate the impact of anti-vascular endothelial growth factor therapy on the refractive error in eyes with diabetic macular edema. (
  • If you find yourself squinting in order to see objects far away in the distance, this is possibly a refractive error in your eyes. (
  • A refractive error can appear in either one eye or in both eyes and can also progress at a different pace in each eye. (
  • If you have bad habits, such as smoking, and spend long hours in front of a screen or a book without allowing your eyes to rest, the chances of developing a refractive error can increase. (
  • Computer-assisted measurement of retinal vessel diameters in the Beaver Dam Eye Study: methodology, correlation between eyes, and effect of refractive errors. (
  • The refractive errors of the students' eyes were measured using non-cycloplegic autorefraction. (
  • If this was any lower, then we wouldn't be able to bend light clearly which is why if you open your eyes underwater everything is slightly out of focus because water has a lower refractive index. (
  • Retinoscopy- Retinoscopy is typically performed during a routine eye exam to determine if the eyes have a refractive error. (
  • Emmetropization is a normal developmental process in which the eyes growth is regulated to achieve a match between eye length and its refractive power. (
  • The World Health Organization's Global Action Plan for 2014 to 2019 has identified human resources for refractive error as a priority in reducing avoidable blindness globally. (
  • therefore identifying and, if possible, addressing the source of this residual error could help surgeons to offer patients improved postoperative outcomes, increasing patient satisfaction with the technique. (

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