Refraction, Ocular: Refraction of LIGHT effected by the media of the EYE.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Myopia: 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.Hyperopia: 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)Emmetropia: The condition of where images are correctly brought to a focus on the retina.Astigmatism: 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)Eyeglasses: 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.Biometry: The use of statistical and mathematical methods to analyze biological observations and phenomena.Anisometropia: A condition of an inequality of refractive power of the two eyes.Axial Length, Eye: The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.Photorefractive Keratectomy: 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.Retinoscopy: 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.Eye: 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.Visual Acuity: 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.Accommodation, Ocular: 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)Corneal Topography: 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.Mydriatics: Agents that dilate the pupil. They may be either sympathomimetics or parasympatholytics.Anterior Chamber: 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)Keratomileusis, Laser In Situ: 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.Cornea: 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)Interferometry: 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).Lasers, Excimer: 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)Myopia, Degenerative: Excessive axial myopia associated with complications (especially posterior staphyloma and CHOROIDAL NEOVASCULARIZATION) that can lead to BLINDNESS.Optometry: 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.Cyclopentolate: A parasympatholytic anticholinergic used solely to obtain mydriasis or cycloplegia.SingaporeVision Screening: 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.Refractive Surgical Procedures: 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.Esotropia: 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.Amblyopia: 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.Vision Tests: A series of tests used to assess various functions of the eyes.Lens Implantation, Intraocular: 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.Strabismus: 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)Presbyopia: The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.Pupil: The aperture in the iris through which light passes.Lenses, Intraocular: Artificial implanted lenses.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.Lens, Crystalline: 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.Cataract: 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)Body Weights and Measures: Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.Lenses: Pieces of glass or other transparent materials used for magnification or increased visual acuity.Tomography, Optical Coherence: 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.Keratotomy, Radial: A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.Refractometry: 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).Prevalence: 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.Asian Continental Ancestry Group: Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.Cataract Extraction: The removal of a cataractous CRYSTALLINE LENS from the eye.Contact Lenses: Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)Intraocular Pressure: The pressure of the fluids in the eye.Phacoemulsification: 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)Vitreous Body: 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.Vision, Low: 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.).Sclera: 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)Ocular Physiological Phenomena: Processes and properties of the EYE as a whole or of any of its parts.Optic Disk: 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.Visually Impaired Persons: Persons with loss of vision such that there is an impact on activities of daily living.Orthokeratologic Procedures: An alternative to REFRACTIVE SURGICAL PROCEDURES. A therapeutic procedure for correcting REFRACTIVE ERRORS. It involves wearing CONTACT LENSES designed to force corrective changes to the curvature of the CORNEA that remain after the lenses are removed. The effect is temporary but is maintained by wearing the therapeutic lenses daily, usually during sleep.Vision Disorders: 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).Choroid: The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.Corneal Wavefront Aberration: Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.Cross-Sectional Studies: 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.Keratectomy, Subepithelial, Laser-Assisted: A surgical technique to correct REFRACTIVE ERRORS of the EYE, such as MYOPIA and ASTIGMATISM. In this method, a flap of CORNEAL EPITHELIUM is created by exposure of the area to dilute alcohol. The flap is lifted and then replaced after laser ablation of the subepithelial CORNEA.Keratoconus: 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)Contact Lenses, Hydrophilic: 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.Optics and Photonics: 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.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Aphakia: Absence of crystalline lens totally or partially from field of vision, from any cause except after cataract extraction. Aphakia is mainly congenital or as result of LENS DISLOCATION AND SUBLUXATION.Glaucoma: 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)Retinopathy of Prematurity: 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)Age Distribution: 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.Aberrometry: 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.Ocular Physiological Processes: Biological action and events that support the functions of the EYE and VISION, OCULAR.Corneal Diseases: Diseases of the cornea.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Eye Diseases: Diseases affecting the eye.Tonometry, Ocular: Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)Macula Lutea: An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)Glaucoma, Angle-Closure: A form of glaucoma in which the intraocular pressure increases because the angle of the anterior chamber is blocked and the aqueous humor cannot drain from the anterior chamber.Reproducibility of Results: 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.Corneal Pachymetry: Measurement of the thickness of the CORNEA.Blindness: 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.Sex Distribution: 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.Microphthalmos: Congenital or developmental anomaly in which the eyeballs are abnormally small.Scleral Diseases: General disorders of the sclera or white of the eye. They may include anatomic, embryologic, degenerative, or pigmentation defects.Tupaiidae: The only family of the order SCANDENTIA, variously included in the order Insectivora or in the order Primates, and often in the order Microscelidea, consisting of five genera. They are TUPAIA, Ananthana (Indian tree shrew), Dendrogale (small smooth-tailed tree shrew), Urogale (Mindanao tree shrew), and Ptilocercus (pen-tailed tree shrew). The tree shrews inhabit the forest areas of eastern Asia from India and southwestern China to Borneo and the Philippines.Exotropia: 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.Surgical Flaps: Tongues of skin and subcutaneous tissue, sometimes including muscle, cut away from the underlying parts but often still attached at one end. They retain their own microvasculature which is also transferred to the new site. They are often used in plastic surgery for filling a defect in a neighboring region.Vision, Binocular: The blending of separate images seen by each eye into one composite image.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Corneal Stroma: The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Anterior Eye Segment: The front third of the eyeball that includes the structures between the front surface of the cornea and the front of the VITREOUS BODY.Postoperative Period: The period following a surgical operation.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Silicone Oils: Organic siloxanes which are polymerized to the oily stage. The oils have low surface tension and density less than 1. They are used in industrial applications and in the treatment of retinal detachment, complicated by proliferative vitreoretinopathy.Tropicamide: One of the MUSCARINIC ANTAGONISTS with pharmacologic action similar to ATROPINE and used mainly as an ophthalmic parasympatholytic or mydriatic.Child Welfare: Organized efforts by communities or organizations to improve the health and well-being of the child.Ethnic Groups: A group of people with a common cultural heritage that sets them apart from others in a variety of social relationships.Photography: Method of making images on a sensitized surface by exposure to light or other radiant energy.New South Wales: A state in southeastern Australia. Its capital is Sydney. It was discovered by Captain Cook in 1770 and first settled at Botany Bay by marines and convicts in 1788. It was named by Captain Cook who thought its coastline resembled that of South Wales. (From Webster's New Geographical Dictionary, 1988, p840 & Room, Brewer's Dictionary of Names, 1992, p377)Keratoplasty, Penetrating: Partial or total replacement of all layers of a central portion of the cornea.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Fovea Centralis: 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)Corneal Transplantation: Partial or total replacement of the CORNEA from one human or animal to another.Aphakia, Postcataract: Absence of the crystalline lens resulting from cataract extraction.Vision, Monocular: Images seen by one eye.Pseudophakia: Presence of an intraocular lens after cataract extraction.Disabled Children: Children with mental or physical disabilities that interfere with usual activities of daily living and that may require accommodation or intervention.Child Behavior: Any observable response or action of a child from 24 months through 12 years of age. For neonates or children younger than 24 months, INFANT BEHAVIOR is available.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Ophthalmoscopy: Examination of the interior of the eye with an ophthalmoscope.China: A country spanning from central Asia to the Pacific Ocean.Disease Progression: The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.Retina: 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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Ophthalmology: A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Microscopy, Acoustic: A scientific tool based on ULTRASONOGRAPHY and used not only for the observation of microstructure in metalwork but also in living tissue. In biomedical application, the acoustic propagation speed in normal and abnormal tissues can be quantified to distinguish their tissue elasticity and other properties.Diseases in Twins: Disorders affecting TWINS, one or both, at any age.Los AngelesVision, Ocular: The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
... , commonly referred to as an A-scan (short for Amplitude scan), is routine type of diagnostic test used in optometry or ophthalmology. The A-scan provides data on the length of the eye, which is a major determinant in common sight disorders. The most common use of the A-scan is to determine eye length for calculation of intraocular lens power. Briefly, the total refractive power of the emmetropic eye is approximately 60. Of this power, the cornea provides roughly 40 diopters, and the crystalline lens 20 diopters. When a cataract is removed, the lens is replaced by an artificial lens implant. By measuring both the length of the eye (A-scan) and the power of the cornea (keratometry), a simple formula can be used to calculate the power of the intraocular lens needed. There are several different formulas that can be used depending on the actual characteristics of the eye. All the information here is not valid for medical purposes. The other ...
0.50 diopter cycloplegic refractive change No evidence of optic-disc edema, nerve sheath distention, choroidal folds, globe flattening, scotoma or cotton-wool spots compared to baseline Class 1 Repeat OCT and visual acuity in 6 weeks Refractive changes ≥ 0.50 diopter cycloplegic refractive change and/or cotton-wool spot No evidence of optic-disc edema, nerve sheath distanton, choroidal folds, globe flattening or scotoma compared to baseline CSF opening pressure ≤ 25 cm H2O (if measured) Class 2 Repeat OCT, cycloplegic refraction, fundus examination and threshold visual field every 4 to 6 weeks × 6 months, repeat MRI in 6 months ≥ 0.50 diopter cycloplegic refractive changes or cotton-wool spot Choroidal folds and/or ONS distention and/or globe flattening and/or scotoma No evidence of optic-disc edema CSF opening pressure ≤ 25 cm H2O (if measured) Class 3 Repeat OCT, cycloplegic refraction, fundus examination ...
The diagram on the right shows an example of refraction in water waves. Ripples travel from the left and pass over a shallower region inclined at an angle to the wavefront. The waves travel slower in the more shallow water, so the wavelength decreases and the wave bends at the boundary. The dotted line represents the normal to the boundary. The dashed line represents the original direction of the waves. This phenomenon explains why waves on a shoreline tend to strike the shore close to a perpendicular angle. As the waves travel from deep water into shallower water near the shore, they are refracted from their original direction of travel to an angle more normal to the shoreline. Refraction is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism. Glass has a higher refractive index than air. When a beam of white light passes from air into a material having an index of ...
... , 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 ...
A dioptre (uk), or diopter (us), is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres). It is thus a unit of reciprocal length. For example, a 3-dioptre lens brings parallel rays of light to focus at 1⁄3 metre. A flat window has an optical power of zero dioptres, and does not converge or diverge light. Dioptres are also sometimes used for other reciprocals of distance, particularly radii of curvature and the vergence of optical beams. The usage was proposed by French ophthalmologist Ferdinand Monoyer in 1872, based on earlier use of the term dioptrice by Johannes Kepler. The main benefit of using optical power rather than focal length is that the lensmaker's equation has the object distance, image distance, and focal length all as reciprocals. A further benefit is that when relatively thin lenses are placed close together their ...
Progressive spectacle lenses, also called progressive addition lenses (PAL), progressive power lenses, graduated prescription lenses, and varifocal or multifocal lenses, are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors. The gradient starts at the wearer's distance prescription, at the top of the lens and reaches a maximum addition power, or the full reading addition, at the bottom of the lens. The length of the progressive power gradient on the lens surface depends on the design of the lens, with a final addition power between 0.75 and 3.50 dioptres. The addition value prescribed depends on the level of presbyopia of the patient. In general the older the patient, the higher the addition. The first patent for a PAL was British Patent 15,735, granted to Owen Aves with a 1907 priority ...
... is a lens implanted in the eye as part of a treatment for cataracts or myopia. The most common type of IOL is the pseudophakic IOL. These are implanted during cataract surgery, after the cloudy eye's natural lens (colloquially called a cataract) has been removed. The pseudophakic IOL provides the same light focusing function as the natural crystalline lens. The second type of IOL, more commonly known as a phakic intraocular lens (PIOL), is a lens which is placed over the existing natural lens, and is used in refractive surgery to change the eye's optical power as a treatment for myopia, or nearsightedness. IOLs usually consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place within the capsular bag inside the eye. IOLs were conventionally made of an inflexible material (PMMA), although this has largely been superseded by the use of flexible materials. Most IOLs fitted today are fixed monofocal lenses matched to distance ...
Some animals suffer from shortsightedness and have poor eyesight. In domestic animals, myopia, with or without astigmatism, occurs frequently. Whereas the rhinoceros may suffer from less-than-adequate eyesight, it generally survives by concentrating with its superior hearing and sense of smell. Some reports, however state that it can see better when focusing with one eye, particularly when walking, posturing, and combatting. Myopia, with or without astigmatism, is the most common eye condition in horses. Several types of occlusion myopia have been recorded in tree shrews, macaques, cats and rats, deciphered from several animal-inducing myopia models. Preliminary laboratory investigations using retinoscopy of 240 dogs found myopic problems with varying degrees of refraction errors depending on the breed. In cases involving German Shepherds, Rottweilers and Miniature horses, the refraction errors were indicative of myopia. Nuclear sclerosis of ...
Cycloplegic drugs are generally muscarinic receptor blockers. These include atropine, cyclopentolate, homatropine, scopolamine and tropicamide. They are indicated for use in cycloplegic refraction (to paralyze the ciliary muscle in order to determine the true refractive error of the eye) and the treatment of uveitis. All cycloplegics are also mydriatic (pupil dilating) agents and are used as such during eye examination to better visualize the retina. When cycloplegic drugs are used as a mydriatic to dilate the pupil, the pupil in the normal eye regains its function when the drugs are metabolized or carried away. Some cycloplegic drugs can cause dilation of the pupil for several days. Usually the ones used by ophthalmologists or optometrists wear off in hours, but when the patient leaves the office strong sunglasses are provided for comfort. ...
... (VA) commonly refers to the clarity of vision. Visual acuity is dependent on optical and neural factors, i.e., (i) the sharpness of the retinal focus within the eye, (ii) the health and functioning of the retina, and (iii) the sensitivity of the interpretative faculty of the brain. A common cause of low visual acuity is refractive error (ametropia), or errors in how the light is refracted in the eyeball. Causes of refractive errors include aberrations in the shape of the eyeball, the shape of the cornea, and reduced flexibility of the lens. Too high or too low refractive error (in relation to the length of the eyeball) is the cause of nearsightedness (myopia) or farsightedness (hyperopia) (normal refractive status is referred to as emmetropia). Other optical causes are astigmatism or more complex corneal irregularities. These anomalies ...
... is an ocular condition where there is a significant difference in the perceived size of images. It can occur as an overall difference between the two eyes, or as a difference in a particular meridian. Gr. "an" = "not", + "is(o)" = "equal," + "eikōn" = "image" Retinal image size is determined by many factors. The size and position of the object being viewed affects the characteristics of the light entering the system. Corrective lenses affect these characteristics and are used commonly to correct refractive error. The optics of the eye including its refractive power and axial length also play a major role in retinal image size. Aniseikonia can occur naturally or be induced by the correction of a refractive error, usually anisometropia (having significantly different refractive errors between each eye) or antimetropia ...
Adjustable focus eyeglasses are eyeglasses with an adjustable focal length. They compensate for refractive errors (such as presbyopia) by providing variable focusing, allowing users to adjust them for desired distance or prescription, or both. Current bifocals and progressive lenses are static, in that the user has to change their eye position to look through the portion of the lens with the focal power corresponding to the distance of the object. This usually means looking through the top of the lens for distant objects and down through the bottom of the lens for near objects. Adjustable focus eyeglasses have one focal length, but it is variable without having to change where one is looking. Possible uses for such glasses are to provide inexpensive eyeglasses for people from low-income groups, developing countries, third world countries or to accommodate for presbyopia. There are currently two basic methods to achieve variable focal ...
In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as stars appearing distorted, appearing to have a tail (coma) like a comet. Specifically, coma is defined as a variation in magnification over the entrance pupil. In refractive or diffractive optical systems, especially those imaging a wide spectral range, coma can be a function of wavelength, in which case it is a form of chromatic aberration.. Coma is an inherent property of telescopes using parabolic mirrors. Unlike a spherical mirror, a bundle of parallel rays parallel to the optical axis will be perfectly focused to a point (the mirror is free of spherical aberration), no matter where they strike the mirror. However, this is only true if the rays are parallel to the axis of the parabola. When the ...
... spherical equivalent refraction at least −0.5 D) was 55.2% (95% CI 52.5 to 57.8). The mean axial length was 23.86 mm (SD 1.06; ... the adjusted mean refractive error of −1.31 D in children whose fathers smoked was not significantly different from refraction ... Children exposed to maternal passive smoke had refractions that shifted towards hyperopia (multivariate adjusted mean −0.28 D; ... Spherical equivalent was defined as sphere +0.5 negative cylinder power. The mean spherical equivalent refraction of the ...
Dobson V Harvey EM Miller JM . Spherical equivalent refractive error in preschool children from a population with a high ... Eye examinations included cycloplegic autorefraction and ocular biometric measures of axial length and corneal curvature. ... both myopia and hyperopia) in 12- to 13-year-old children and with hyperopia in 6- to 7-year-old children. There is a low ... The Northern Ireland Childhood Errors of Refraction (NICER) study is a population-based survey of school children aged 6-7 ...
Axial Length. Temporal Spherical Equivalent (30°) Temporal Spherical Equivalent (15°) Central Spherical Equivalent Nasal ... Children with the highest quartile of axial length were myopic at the center (−3.76 D) and had relatively more hyperopia at the ... Axial Length. Temporal Spherical Equivalent (30°) Temporal Spherical Equivalent (15°) Central Spherical Equivalent Nasal ... Temporal Spherical Equivalent (15°) Central Spherical Equivalent Nasal Spherical Equivalent (15°) Nasal Spherical Equivalent ( ...
... they had bilateral refraction errors of +5.00 D or higher (spherical equivalent) and 2) they had no other known ocular or ... is a common refractive error in children and adults [1-3]. Hyperopia may be classified as low hyperopia (+2.00 diopters [D] or ... Since the simple hyperopia cases represent a less severe form of a short axial length that is similar to the delineation of ... refraction of spherical equivalent ≥+5.00 [diopters] D) and 96 controls (refraction of spherical equivalent between −0.50 D and ...
Refractions have been shown as spherical equivalent and averaged between the two eyes (except case 4 which was a unilateral ... and an increase in axial length (especially vitreous length), often asymmetrically. The myopia due to increased axial length is ... Human adults show a non-Gaussian distribution of refractive errors with a predominance of refractions around emmetropia. Other ... in particular vitreous length) in congenital glaucoma is related to the compliance of the connective tissue in children that ...
Hence measurement of CCT plays an important role in these refractive errors. Emmetropia is defined as spherical equivalent ... Relationship between central corneal thickness, refractive error, corneal curvature, anterior chamber depth and axial length. J ... Similarly CCT did not show any statistical significance between the refractive error groups (myopia and hyperopia) and its ... Cornea is the major refractive element of the eye where it contributes approximately two-thirds of optical refraction . For ...
... initial mean spherical equivalent refraction, and initial mean axial length. Mean axial length change and dropout rates were ... C. C. A. Sng, X.-Y. Lin, G. Gazzard et al., "Peripheral refraction and refractive error in Singapore Chinese children," ... Orthokeratology flattens the central cornea while steeping midperipheral to reduce relative peripheral hyperopia, which would ... Axial length change and dropout rates during the 2-year follow-up were assessed as the primary outcomes. The mean axial length ...
The average value was recorded and the refraction was expressed as spherical equivalent (SE). The SE is the sum of spherical ... We had 282 children with a wider range of age. Another study on Australian children found that axial length and corneal radius ... J. Wang, X. Ren, L. Shen, S. E. Yanni, J. N. Leffler, and E. E. Birch, "Development of refractive error in individual children ... The children were divided into three groups according to their refractive status (emmetropia,myopia, and hyperopia), ages (4-7 ...
Note the relationship showing an increase of the axia length with increasing age. ... Relationship between axial length (mm) and age (years). ... trend for a decrease of the spherical equivalent from hyperopia ... Purpose: We analyzed the effect of the changes of the optic disc area (ODA) caused by the axial length and the refractive error ... Mentions: As the childrens age increased, a trend for a decrease of the spherical equivalent from hyperopia to myopia was ...
... the mean spherical equivalent was ?0.8 +/- 0.83D [range, +1.25 to ?3.75D]. The mean postoperative refractive SE when implanting ... In all 127 eyes, the mean axial length was 31.71 mm [range, 26.06-37.11 mm] and the mean K was 44.68 D [range, 40.05-55.14D]. ... Adult , Adolescent , Aged , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Real-Time Polymerase Chain ... Differences between actual postoperative refraction and assumed target refraction using the different formulas were analyzed. P ...
... the mean spherical equivalent was -0.8 ± 0.83D (range, +1.25 to -3.75D). The mean postoperative refractive SE when implanting a ... calculation formulas in predicting a target postoperative refraction ± 1.0D (Diopters) in patients with long eyes (axial length ... most postoperative refractive error was within +1.0 to +2.0D in the actual implanted IOL and in all other formula calculated ... Purpose : To identify under-five-year-old children with vision or ocular defect in two provinces (Wilayats) of central Oman in ...
Axial length and corneal curvature are the key determinants of refractive error. The first GWA study of axial length involved ... 12 previously implicated genetic regions and revealed four newly reported genetic variants associated with spherical equivalent ... Notably, the 15q14 region was associated with hyperopia, which represents the other end of the refractive error continuum. ... and biometric components of refraction including axial length, corneal curvature, corneal power, lens thickness, and lens power ...
The spherical equivalent refraction (SER) was calculated as the spherical value of the refractive error plus half of the ... Additionally, we did not measure axial length, which would have complemented our data. Finally, strict statistical ... Refractive error, visual acuity and causes of vision loss in children in Shandong, China. The Shandong children eye study. PLoS ... the refractive error (RE) was defined as non-myopia (−0.5 ≤ SER diopters (D), including hyperopia and emmetropia), low myopia ...
As the eye grows, the axial length increases while the cornea and lens flatten. High refractive errors which are common in the ... ranging from 16-51). The mean manifest refraction (spherical equivalent) was -4.9 +/- 2.29 diopters (ranging from -0.50 to - ... Humans , Child, Preschool , Child , Adolescent , Adult , Middle Aged , Astigmatism/epidemiology , Hyperopia/epidemiology , ... When hyperopia is associated with esotropia, full correction of the cycloplegic refractive error should be prescribed. Myopia ...
Refractive error, axial length, and relative peripheral refractive error before and after the onset of myopia. Invest ... Having determined a childs best distance refraction, it is imperative to know how this influences their near point binocular ... Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: one-year results. ... spherical aberration and binocular vision, and would likely be best suited to a contact lens modality. It may also include real ...
... association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the ... tracking changes in refractive error, corneal curvature and axial length over a 14-year period.60 Like the Norwegian and ... While the natural history of refractive error has been fairly well documented in children and adolescents,103-107 refractive ... the 1-year incidence of refractive error (non-cycloplegic refraction) and pterygium will be analysed using data from ...
equivalent lens See spherical equivalent.. lens exfoliation See exfoliation of the lens.. extended wear lens A contact lens ... In farsightedness (hyperopia) the image is focused behind the retina because the refractive power of the lens is too weak or ... To obtain the correct lens power it is necessary to measure corneal curvature and axial length of the eye. Several formulae ... Sometimes it also includes lenses used to measure the refractive error.. ortho-k lens A rigid gas permeable contact lens used ...
... spherical equivalent refraction (SER), axial length (AL) and anterior chamber depth (ACD) significantly differed by refractive ... Greater height is associated with a longer AL but not with refractive error in Asian adults.15,16 In Asian children, a greater ... Literature reports that fogging lenses produce a similar effect to cycloplegia in those with hyperopia and also reports no ... spherical equivalent refraction (SER), axial length (AL) and anterior chamber depth (ACD) significantly differed by refractive ...
... reviews current options for slowing the progression of myopia in children based on the latest information in the peer-reviewed ... spherical equivalent of the distance manifest refraction. An over-refraction incorporated into the distance power of the soft ... STUDY LENGTH (YEARS). SLOW MYOPIA PROGRESSION (%). SLOW AXIAL ELONGATION (%). Allen (2013)29. Gradient. Yield -0.1µ SA. ... Myopia progression cannot be measured with orthokeratology due to the temporary reduction of myopic refractive error that the ...
... for patients with low-level hyperopia and presbyopia has been widely successful throughout the world, the surgical correctional ... All the treatments were based on preoperative cycloplegic refraction spherical equivalent (CRSE). Eligible patients for the ... In hyperopia, the axial length (measurement of the most anterior part of the cornea to the most posterior part of the sclera) ... The degree of blur depends on the amount of refractive error present. Both near vision and distance vision may be affected. Age ...
... presents several advantages over corneal refractive surgery. Patients with high degrees of myopia, hyperopia and astigmatism ... in combination with corneal astigmatic procedures might address all refractive errors including presbyopia, and eliminate the ... Removal of the crystalline lens for refractive purposes or refractive lens exchange (RLE) ... As the outcomes of cataract surgery became better, the use of lens surgery as a refractive modality in patients without ...
While excellent surgical options exist for the treatment of low (3.00 D or less of myopic spherical equivalent error) to ... Regardless of the cause, using different tools such as an intraoperative aberrometer or an optimized axial length (AL) formula ... It can accurately treat myopic refractive errors up to 12.00 D.. However, potential problems can crop up. Corneal ectasia and ... RLE for children?. One instance in which RLE is a successful, clinically indicated treatment of choice for a young patient ...
... between the refractive prediction errors calculated using the five formulas and ocular dimensions such as axial length (AL), ... RESULTS: The study was conducted on 54 patients (33.9 ± 14.1 years of age) with a spherical equivalent (M) refraction ... Differences in ocular biometry between urban and rural children matched by refractive error: the Shandong Children Eye Study. ... With advancing age, refractive surgery was performed for lower magnitudes of myopia and hyperopia. The magnitude of cylinder ...
Percentage of Eyes Achieving Manifest Refraction Spherical Equivalent (MRSE) Within ± 1.0 D of Zero at Refractive Stability ... Prevalence of axial length. 808. All. 40 Years to 100 Years (Adult, Senior). NCT03159780. ZhongshanOC20170503. January 1, 2017 ... Child, Adult, Senior. NCT00521833. 8380. June 2005. August 2006. August 28, 2007. September 5, 2007. *Ophthalmic research ... Safety and Efficacy of Corneal Collagen Cross-linking Following LASIK for Treatment of Hyperopia and Hyperopic Astigmatism. * ...
2009) Heritability analysis of spherical equivalent, axial length, corneal curvature, and anterior chamber depth in the Beaver ... We then found that numerous SNPs within the 5-end of APLP2 were associated with refractive error development in children and ... Sex was not significantly associated with refractive error in the refraction trajectory analyses and so was dropped from the ... Failure to achieve or maintain emmetropia leads to the development of refractive errors, i.e., farsightedness (hyperopia) or ...
AstigmatismMyopic refractiveCommon refractive errorDioptersRole in refractiveAverage sphericalPrevalence of refractiveIncluding the development of myopiaConclusionsFarsightednessBiometricCentral Corneal ThicknessOutcomesCorrelationStrabismusHyperopicMethodsOcular biometrySurgeriesCataract surgeryPresbyopiaSurgeonsAnisometropiaRetinalCorneal powerExcimerEmmetropicRelative peripheralPostoperativelyProgressionPatientsCorrectionInduceContrast sensitivityBaselineAnteriorCiliaryOrthokeratologyHeritability0.001PathologicLens exchangeHumansGlaucomaMyopesCorrelateDegreesResults3.00HighChildhood12.00Ophthalmology
- To study the prevalence of and relation between refractive and corneal astigmatism in white school children in Northern Ireland and to describe the association between refractive astigmatism and refractive error. (arvojournals.org)
- The prevalence of refractive astigmatism was associated with increasing myopia and hyperopia. (arvojournals.org)
- This study is the first to provide robust population-based data on the prevalence of astigmatism in white school children in the United Kingdom. (arvojournals.org)
- The prevalence of refractive astigmatism and corneal astigmatism is stable between 6 and 7 years and 12 and 13 years, although this finding would need to be confirmed by prospective studies. (arvojournals.org)
- There is a high prevalence of refractive and corneal astigmatism which is associated with ametropia. (arvojournals.org)
- 5 Two components of astigmatism can currently be independently measured: refractive astigmatism and corneal astigmatism, with the difference between these being due to internal astigmatism. (arvojournals.org)
- Due to the effect of internal astigmatism, the magnitude of corneal astigmatism is generally greater than that of refractive astigmatism. (arvojournals.org)
- As the population of Northern Ireland is ethnically homogenous (99% white), 11 the purpose of the present study is to describe the prevalence of refractive astigmatism in white school children, facilitating comparisons with other population-based surveys examining school-age children of predominantly European origin in Europe, Australia, and the United States. (arvojournals.org)
- Results: We have found a prevalence of refractive defects of 18.8% were 13.4% represented astigmatism, 3.6% farsightedness and 1.8% shortsightedness. (bvsalud.org)
- Refractive lens exchange is an effective surgical alternative when corneal laser refractive surgery may not be, such as for myopia greater than 10.00 D, irregular or higher levels of astigmatism, thin corneas or the patient's desire for presbyopia correction. (lasikindia.in)
- Patients with high degrees of myopia, hyperopia and astigmatism are still not good candidates for laser surgery. (biomedcentral.com)
- Myopic patients with at least 1 diopter (D) of anisometropia in sphere, astigmatism, or spherical equivalent who were referred to our hospital for excimer refractive surgery were enrolled as a prospective sequential interventional case series. (jovr.org)
- In one of the earliest studies on myopia heritability, Karlsson identified that 94 per cent of the identical twins who participated had similar myopic refractive power compared to 29 per cent in non-identical twins. (mivision.com.au)
- It can accurately treat myopic refractive errors up to 12.00 D. (lasikindia.in)
- Pathologic myopia is generally classified as a high myopic refractive error that is progressive and generally presents very early in childhood. (eyewiki.org)
- DNA was prepared from venous leukocytes of 51 patients with physiologic high hyperopia (refraction of spherical equivalent ≥+5.00 [diopters] D) and 96 controls (refraction of spherical equivalent between −0.50 D and +1.00 D). The coding regions and adjacent intronic sequence of MFRP were amplified by polymerase chain reaction (PCR) and were then analyzed by cycle sequencing. (molvis.org)
- Summit Laser then introduced its holmium:YAG laser, first successfully used by Theo Seiler, MD, in 1990 for contact laser thermal keratoplasty (LTK) for the correction of hyperopia of up to 5 diopters (D), which also eventually failed. (medscape.com)
- However, recent interest into understanding the influence of peripheral refraction on central refractive error has increased, and studies suggest that peripheral refractive error may play a key role in refractive eye development. (arvojournals.org)
- 7 Accordingly, it has been hypothesised that neural forms of nicotinic acetylcholine receptors in the retina might have a role in refractive development. (bmj.com)
- There was a suggestion that children whose mothers smoked cigarettes had more hyperopic refractions, but the absence of a relation with paternal smoking and the small number of mothers who smoked in this sample preclude definite conclusions about a link between passive smoking exposure and myopia. (bmj.com)
- Conclusions: These findings show that short-wavelength light slows refractive eye growth, producing hyperopic responses in mice and inhibiting lens-induced myopia. (bvsalud.org)
- Numerous studies have been carried out to find out the relations of refractive error and ocular biometric measures with birth parameters in preterm or low birth weight child at birth and in the long term [ 6 , 9 - 13 ]. (hindawi.com)
- A few studies investigated the association of birth parameters and refraction or biometric parameters in the general population of children [ 14 - 16 ]. (hindawi.com)
- As the outcomes of cataract surgery became better, the use of lens surgery as a refractive modality in patients without cataracts has increased in interest and in popularity. (biomedcentral.com)
- The oculoplastic considerations for refractive surgery include both the contribution of eyelid position on dry eye, ocular surface damage, refractive error, and outcomes, as well as the timing of oculoplastic surgery in relation to the refractive surgery. (bvsalud.org)
- In this review, the recently published literature on eyelid and orbital surgery in relation to keratorefractive surgery is reviewed to elucidate the relationship of periocular factors with refractive surgery outcomes and complications. (bvsalud.org)
- After making an adjustment for gestational age and birth weight in a logistic regression model, mean SEQ was not significantly different between two groups (p = .61)Conclusion: At adjusted 1 year of age, refractive outcomes were not significantly different between premature infants who underwent IVB injection and the infants with spontaneous regression of ROP. (bvsalud.org)
- Hence the purpose of the study was to determine the correlation of CCT between different refractive errors and age groups. (alliedacademies.org)
- On the one hand, another study on preterms from 2 weeks to 6 months of age reported no correlation of refractive error to GA or BW [ 7 ]. (hindawi.com)
- In addition, the correlation of the refractive error and the axial length to the optic disc factors was assessed. (nih.gov)
- Many family studies have indicated that there is a positive correlation between myopia in parents and children. (mivision.com.au)
- 4 A significant correlation between undercorrection and myopia progression may indicate that the studies that found no effect simply didn't undercorrect the myopia enough, but doing so would put the myopic children at a disadvantage due to poor distance vision. (clspectrum.com)
- Effective refractive power (EffRP) measured using EyeSys was most similar to the values obtained using cHM (Icc, intraclass correlation coefficient = 0.951), followed by the total corneal power measured using the Galilei system (Icc = 0.943). (jovr.org)
- Two hundred fifty children aged 40 months or older recruited from the Strabismus, Amblyopia, and Refractive Error in Young Singapore Children study were included in this analysis. (arvojournals.org)
- We applied the MBT using the streak retinoscope to identify anisometropia and strabismus by noting an inter-ocular difference in movement and glow, from children who failed 6/9 Snellen on community vision screening, followed by comprehensive eye examination. (ojoonline.org)
- Our data suggests that the MBT is highly accurate and useful for ruling in anisometropia and strabismus in children who fail 6/9 Snellen. (ojoonline.org)
- Purpose: To assess refractive errors in preterm infants following intravitreal bevacizumab (IVB) injection for retinopathy of prematurity (ROP) and to compare it with premature babies with spontaneous regressed ROP.Materials and Methods: Eighty seven premature infants were included in this study, comprising group1: 38 infants who underwent IVB monotherapy, and group2: 49 infants with spontaneously regressed ROP. (bvsalud.org)
- Corneal pachymetry helps in the assessment of corneal oedema, effectivity of corneal refractive surgeries, suspicious glaucoma, bullous keratopathy, corneal oedema, posterior polymorphous dystrophy, Fuchs endothelial dystrophy and keratoconus during eye examination. (alliedacademies.org)
- In addition to impacting dry eye and ocular surface damage, eyelid surgeries can also affect corneal topography and refraction. (bvsalud.org)
- Cataract surgery due to advances in small incision surgery evolved from a procedure concerned with the primary focus on the safe removal of cataractous lens to a procedure focused on the best possible postoperative refractive result. (biomedcentral.com)
- RLE supplemented with multifocal or accommodating intraocular lenses (IOLs) in combination with corneal astigmatic procedures might address all refractive errors including presbyopia, and eliminate the future need for cataract surgery. (biomedcentral.com)
- The surgical technique of refractive lens exchange (RLE) is a variation of standard cataract surgery. (biomedcentral.com)
- The main elements that make a difference between standard cataract surgery and RLE are: clarity of crystalline lens in the absence of cataract, and a presence of abnormal ocular anatomy resulting in a high refractive error, which becomes an indication for RLE. (biomedcentral.com)
- Correction of presbyopia and gaining spectacle-independence in elderly patients with no anatomical ocular pathologies and normal axial length is also an important indication for RLE. (biomedcentral.com)
- Although nonsurgical correction (ie, glasses, contact lenses ) for patients with low-level hyperopia and presbyopia has been widely successful throughout the world, the surgical correctional procedures have been somewhat less accepted. (medscape.com)
- The central problem in the correction of hyperopia and presbyopia is the pressing challenge of steepening the central cornea. (medscape.com)
- While excellent surgical options exist for the treatment of low (3.00 D or less of myopic spherical equivalent error) to moderate (3.25 D to 6.00 D) myopia, the treatment of high myopia remains one of the greater challenges refractive surgeons face today. (lasikindia.in)
- Corneal ectasia and its prevention is a top concern for refractive surgeons at all times. (lasikindia.in)
- 1, 2 Recent laboratory research has shown that visual input modulates refractive development, and has implicated a variety of neural and retinal mechanisms in experimental animals, with initial extrapolation to humans. (bmj.com)
- The effects of optic disc factors on retinal nerve fiber layer thickness measurement in children. (nih.gov)
- We analyzed the effect of the changes of the optic disc area (ODA) caused by the axial length and the refractive error, and the consequent changes of the distance from the optic disc margin to the circular scan (OD-CS) of Optical coherence tomography (OCT) on the measurement of the retinal nerve fiber layer thickness(RNFLT) were examined. (nih.gov)
- Patients with high axial myopia are at a greater risk of developing progressive retinal degeneration and other vision threatening pathology. (eyewiki.org)
- 9 ] concluded that the following induced abnormal axial growth of the eye: near accommodation lag, mechanical tension created by the crystalline lens or ciliary body, and peripheral retinal signal domination. (biomedcentral.com)
- The correlations between the refractive prediction errors calculated using the five formulas and ocular dimensions such as axial length (AL), anterior chamber depth (ACD), corneal power, and lens thickness (LT) were analyzed. (bvsalud.org)
- The values obtained using the adjusted EffRP formula (EffRP - 0.015*Δ Refraction - 0.05) were more consistent with the values obtained using cHM (Icc = 0.954) compared to those obtained with the adjusted average central corneal power formula measured using the Tomey system (Icc = 0.919). (jovr.org)
- Corneal excimer laser surgery (LASIK, advanced surface ablation), refractive lens exchange (RLE) and phakic lens technology / ICL are the options I will address here. (lasikindia.in)
- Corneal excimer laser surgery - LASIK and advanced surface ablation techniques including PRK, LASEK and Epi-LASIK - is undoubtedly the most popular refractive surgical procedure performed in the pre-cataract population. (lasikindia.in)
- 7 who observed that pilots who became myopic during their training had relative peripheral hyperopia before the onset of myopia. (arvojournals.org)
- The ideal myopia-controlling device has yet to be designed - it would include beneficial alteration of relative peripheral optics, spherical aberration and binocular vision, and would likely be best suited to a contact lens modality. (aop.org.uk)
- Refraction 6 months postoperatively revealed myopia of −10.5 D in both eyes. (bmj.com)
- Subsequent refraction at age 2 (18 months postoperatively) revealed reduced myopia of −4.5D in both eyes. (bmj.com)
- EUA at age 42 months (36 months postoperatively) revealed refraction of +0.5DS in both eyes which has remained stable on subsequent review to date (now 5 years postoperatively). (bmj.com)
- To evaluate the efficacy and acceptability of orthokeratology for slowing myopic progression in children with a well conducted evidence-based analysis. (hindawi.com)
- Orthokeratology is effective and acceptable for slowing myopic progression in children with careful education and monitoring. (hindawi.com)
- Slowing of myopia progression can be designated as a dioptric difference in progression between treatment and control groups over a specified period of time, as the proportion of children who progress a specified amount, or in a myriad of other ways. (clspectrum.com)
- Refractive results have often been reported from these animal models and have formed the basis for progression to human treatment. (biomedcentral.com)
- Myopia is a significant, prevalent disease in children with increasing rates of progression. (eyewiki.org)
- Ortho-k lenses are effective in controlling myopic progression in Chinese children, particularly in younger children and in children with higher myopia. (biomedcentral.com)
- Mutations in the membrane-type frizzled-related protein ( MFRP ) gene have been identified in patients with pathologic high hyperopia associated with nanophthalmos or microphthalmia. (molvis.org)
- Patients electing to have oculoplastic surgery, like ptosis repair, should be fully healed prior to any refractive surgery to allow both refractive changes and eyelid positions to stabilize prior to the refractive surgery. (bvsalud.org)
- Patients with myopia who were candidates for corneal refractive surgery were sequentially included. (jovr.org)
- To assess and compare preoperative refractive, aberrometric, topographic, and contrast sensitivity (CS) measurements with postoperative values after corneal collagen cross-linking (CXL) in patients with progressive keratoconus. (jovr.org)
- Laser and laserlike surgical procedures for the correction of hyperopia have a checkered history. (medscape.com)
- New techniques and technologies for refractive correction are continually emerging and hence experimental animal models have regularly been used to simulate and investigate these advances before patient application. (biomedcentral.com)
- The pertinent data from examination results were retrieved and rearranged from the medical records of children who came to our clinic for vision correction using spectacles or ortho-k lenses from 2013 to 2014. (biomedcentral.com)
- However, these studies differed in baseline refraction, baseline age, axial length measurements, ethnicities, and type of treatment and control, with some limited by small sample sizes. (hindawi.com)
- PURPOSE: To evaluate the repeatability of objective measurements of AA using the TONOREF III and explored the association between objectively measured AA and factors, including age, sex, spherical equivalent, baseline pupil size and pupil size change during accommodation. (bvsalud.org)
- Children from previously reported comparative studies were treated by orthokeratology versus control. (hindawi.com)
- At 2-year follow-up, a statistically significant difference was observed in axial length change between the orthokeratology and control groups, with a weighted mean difference (WMD) of −0.25 mm (95% CI, −0.30 to −0.21). (hindawi.com)
- To investigate the effectiveness of orthokeratology (ortho-k) in reducing the development of myopia in Chinese children with low to moderate myopia. (biomedcentral.com)
- 3 Verifying this work, larger studies estimated the heritability of refraction from 50 per cent to 91 per cent and myopia inheritance between 11 per cent to 98 per cent. (mivision.com.au)
- In these studies, heritability can be estimated from degree of resemblance between siblings, parent-child, second, and third-degree relatives. (mivision.com.au)
- The estimated heritability of refractive error in siblings over 70 years was 61 per cent in the Salisbury Eye Evaluation Study (SEES) in Maryland and on average, odds of having myopia was 2.72 times higher in siblings of myopic individuals than in siblings of nonmyopic participants. (mivision.com.au)
- Refractive lens exchange in modern practice: when and when not to do it? (biomedcentral.com)
- Removal of the crystalline lens for refractive purposes or refractive lens exchange (RLE) presents several advantages over corneal refractive surgery. (biomedcentral.com)
- First systematically conducted operations of clear lens exchange in high myopia in children and young adults were made by Polish ophthalmologist Vincenz Fukala in the last decades of the 19th century in Vienna. (biomedcentral.com)
- To explore the potential applicability of this hypothesis to humans, we sought an association of refractive development in young children with nicotine exposure through passive smoking by their parents. (bmj.com)
- It also demonstrates an important role for APLP2 in refractive development in mice and humans, suggesting a high level of evolutionary conservation of the signaling pathways underlying refractive eye development. (plos.org)
- Documented differences between various refractive groups may contribute to the ongoing research in the field of glaucoma and LASIK. (alliedacademies.org)
- The children with neurologic sequela such as mental retardation and cerebral palsy and those who had ocular diseases such as glaucoma, cataract, and history of treatment for retinopathy of prematurity and those who had undergone any ocular surgery were excluded. (hindawi.com)
- No significant correlations were found between CCT and the amount of spherical equivalent in hyperopes and myopes. (alliedacademies.org)
- 9-11 A key research finding in large-scale studies is that the fastest change in refraction occurs in the year just prior to myopia onset, 10 so it is crucial to watch these at-risk future myopes closely for shifts in their risk profile and especially in their manifest hyperopia. (aop.org.uk)
- Our results imply that MFRP is less likely to play a major role in physiologic high hyperopia. (molvis.org)
- Results: In WT mice, short-wavelength violet light induced hyperopia and violet light inhibited lens-induced myopia when compared with mice exposed to white light. (bvsalud.org)
- RESULTS: There were significant differences in the median absolute error predicted by the five formulas after the adjustment for mean refractive prediction errors to zero (P = 0.038). (bvsalud.org)
- This study is to test if a mutation in MFRP is responsible for physiologic high hyperopia. (molvis.org)
- Most cases of high hyperopia are physiologic high hyperopia that is not associated with other ocular or systemic anomalies. (molvis.org)
- Children who exhibit myopia by age six to seven years are over six times more likely to progress to high myopia (over 5D) compared to older age of onset of 11-12 years of age, independent of ethnicity and gender. (aop.org.uk)
- This cross-sectional study included children aged 4 to 17 years who had been examined at the Department of Ophthalmology in 2013. (hindawi.com)
- Edward E. Manche, MD is Professor of Ophthalmology and Director of the Cornea and Refractive Surgery Service at Stanford University School of Medicine. (stanford.edu)
- He serves on the editorial boards of the American Journal of Ophthalmology, Journal of Ophthalmology, Clinical and Experimental Ophthalmology and Journal of Refractive Surgery. (stanford.edu)