• The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. (wikipedia.org)
  • Astigmatism: A person with astigmatic refractive error sees lines of a particular orientation less clearly than lines at right angles to them. (wikipedia.org)
  • The authors make some fundamental errors in their use of vectors for the calculation of mean astigmatism and have failed to refer to the dependence of astigmatism on the overall refractive power. (bmj.com)
  • As clearly discussed by several authors, 2-4 it is inappropriate to analyse astigmatism without analysing the overall change in refractive power. (bmj.com)
  • In addition, patients are at risk for refractive amblyopia caused by keratitis-induced astigmatism. (chop.edu)
  • This discrepancy is due to the contributions of the posterior corneal curvature or surgically induced astigmatism. (crstoday.com)
  • Even without visual axis obstruction, the eyelid may induce refractive errors, especially astigmatism resulting in amblyopia. (medscape.com)
  • Expand your knowledge in refractive, cornea, cataract and lens-based surgery by joining the strongest network of refractive surgeons worldwide. (isrs.org)
  • Gain access to hundreds of refractive, cataract and cornea videos on the ISRS Multimedia Library. (isrs.org)
  • Refractive error, also known as refraction error, is a problem with focusing light accurately on the retina due to the shape of the eye and or cornea. (wikipedia.org)
  • Refractive surgery permanently changes the shape of the cornea. (wikipedia.org)
  • This can arise from a cornea or crystalline lens with not enough curvature (refractive hyperopia) or an eyeball that is too short (axial hyperopia). (wikipedia.org)
  • Corneal refractive surgery alters the curvature of the cornea to focus light more precisely on the retina. (msdmanuals.com)
  • Overview of Refractive Error In the emmetropic (normally refracted) eye, entering light rays are focused on the retina by the cornea and the lens, creating a sharp image that is transmitted to the brain. (msdmanuals.com)
  • The authors concluded that following 90 minutes of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal edema compared to standard scleral lens wear in young adults with healthy corneas, and this approach may potentially be suitable to address poor front-surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting. (constantcontact.com)
  • Missing the target refraction by one diopter (or even less) might lead to significant dissatisfaction and to the search for measures to deal with the residual refractive error. (medscape.com)
  • Circumlimbal suture provides a simple and cost-effective way to induce mild chronic ocular hypertension in rat eyes. (arvojournals.org)
  • In the past decades, a number of animal models of glaucoma have been developed, 3 - 5 all of which aim to induce chronic ocular hypertension (OHT) and selective ganglion cell apoptosis. (arvojournals.org)
  • The incidence of herpes simplex keratitis (HSK) in patients following corneal refractive surgery is higher than in the general population, and several case reports of ocular morbidity in HSK infection following corneal refractive surgery have been published. (dovepress.com)
  • Treatment options after laser-pointer-induced ocular trauma are limited. (aerzteblatt.de)
  • Steroid-induced glaucoma is a form of open-angle glaucoma that usually is associated with topical steroid use, but it may develop with inhaled, oral, intravenous, periocular, or intravitreal steroid administration. (medscape.com)
  • [ 1 ] Dietary supplements have also been reported to induce acute angle-closure glaucoma. (medscape.com)
  • Most categories of drugs that list glaucoma as a contraindication or adverse effect are concerned with inducing acute angle-closure glaucoma. (medscape.com)
  • Sulfa containing medications may induce angle-closure glaucoma by a different angle-closure mechanism, involving anterior rotation of the ciliary body. (medscape.com)
  • Exact pathophysiology of steroid-induced glaucoma is unknown. (medscape.com)
  • The pathophysiology of drug-induced angle-closure glaucoma is usually increased pupillary block (ie, increased iris-lens contact at the pupillary border) from pupillary dilation. (medscape.com)
  • One possible reason is that the techniques employed to produce chronic OHT in experimental glaucoma also unintentionally induce pathological sequelae not typical of glaucoma. (arvojournals.org)
  • Refractive Surgery for the Glaucoma Suspect When it comes to performing refractive surgery in patients at risk for glaucoma, what factors should be considered? (medscape.com)
  • Advances in technology have expanded both the treatment options and pool of candidates for refractive lensectomy. (crstoday.com)
  • Ideal candidates for refractive surgery are healthy people aged 18 and older with healthy eyes who are not satisfied wearing eyeglasses or contact lenses. (msdmanuals.com)
  • Hamed AM, Wang L, Misra M, Koch DD " A comparative analysis of five methods of determining corneal refractive power in eyes that have undergone myopic laser in situ keratomileusis. . (bcm.edu)
  • HSK is listed by the American Academy of Ophthalmology as a relative contraindication to corneal refractive surgery, although specifics have not been further elucidated. (dovepress.com)
  • This review summarizes the current literature regarding reactivation of HSK following corneal refractive surgery and provides a guideline for considering corneal refractive surgery in a patient with a previous history of HSK. (dovepress.com)
  • Based on the current literature, we recommend that corneal refractive surgery is appropriate for patients with a history of HSK without multiple recurrences who have had no evidence of disease for at least one year. (dovepress.com)
  • Success with these lenses demands that surgeons reduce postoperative refractive errors. (crstoday.com)
  • Dr Waring presented the next generation of postoperative refractive adjustment, which is performed by our preferred instrument in cataract surgery: the femtosecond laser. (medscape.com)
  • An eye that has no refractive error when viewing distant objects is said to have emmetropia or be emmetropic meaning the eye is in a state in which it can focus parallel rays of light (light from distant objects) on the retina, without using any accommodation. (wikipedia.org)
  • When images are not properly focused on the retina, a refractive error exists. (myhealth.gov.my)
  • To induce chronic intraocular pressure (IOP) elevation in rat eyes by circumlimbal suture. (arvojournals.org)
  • This is due to a combination of retinal breaks, vitreous changes inducing a retinal break and vitreoretinal traction, and intraocular fluid currents. (aao.org)
  • My work focuses on improving the outcomes of cataract surgery and refractive surgery procedures such as LASIK and PRK. (bcm.edu)
  • The line between offering cataract surgery for a visually significant cataract or lensectomy as a primary refractive procedure can be ambiguous. (crstoday.com)
  • When patients exhibit early lens changes but retain full visual function, the conversation typically veers away from cataract surgery toward refractive lensectomy. (crstoday.com)
  • The strategies to attract refractive lensectomy versus cataract surgery patients may differ, even for surgeons who offer laser vision correction. (crstoday.com)
  • The conversation with these patients pivots to an explanation that the cataract is not quite ready for surgery but that the lens can be removed to correct their refractive error, reduce their dependence on glasses, improve their lifestyle, and prevent their need for cataract surgery in the future. (crstoday.com)
  • Aims To report the refractive error difference (RED) between parents and their children and the estimated single generational myopic shift in an urban area in China. (bmj.com)
  • Patients with dysfunctional lens syndrome notice presbyopia and annual shifts in their refractive error. (crstoday.com)
  • Instead, I identify the problem as refractive error and present options to reduce it, treat their presbyopia to extend their range of focus, and abate the routine shift in refractive error that annually requires them to obtain a new glasses prescription. (crstoday.com)
  • The conversation shifts to explaining that factors such as age, refractive error, presbyopia onset, and early lens changes make lens-based refractive surgery a better option. (crstoday.com)
  • Currently, presbyopia can be corrected by refractive surgery (LASIK). (myhealth.gov.my)
  • Excellent postoperative uncorrected and best-corrected visual acuity levels were achieved after PTK and fairly good refractive outcomes as well. (ophthalmologytimes.com)
  • This study investigated long-term outcomes of hyperoxia on retinal morphology and function using a mouse model of oxygen-induced ischemic retinopathy (OIR). (molvis.org)
  • Hear experts speak on cutting-edge subjects not listed in the official program while networking with refractive surgeons from around the world. (isrs.org)
  • Expand your patient base with a listing in the Find a Refractive Surgeon online directory that the public uses to find refractive surgeons. (isrs.org)
  • Patients' high expectations combined with the complex optics of these lenses makes it imperative that we surgeons fully correct refractive errors. (crstoday.com)
  • Koch DD " An aphoristic guide to building a refractive surgical practice. . (bcm.edu)
  • Some refractive errors occur more often among those whose parents are affected. (wikipedia.org)
  • The number of people globally with refractive errors has been estimated at one to two billion. (wikipedia.org)
  • The number of people with refractive errors that have not been corrected was estimated at 660 million (10 per 100 people) in 2013. (wikipedia.org)
  • Conclusions In this sample, children's refractive errors at the age of 11 years were already similar to their parents. (bmj.com)
  • 5 However, few studies have reported the quantitative relation between refractive errors in parents and their children. (bmj.com)
  • 1983 ) On the use of matrices for the mean value of refractive errors. (bmj.com)
  • The eye discomfort was found to increase as the day progressed being accompanied by the appearance of headache and fatigue, without refractive errors or changes in amplitude of accommodation, pupil size, phorias and fusional capacity. (cdc.gov)
  • It reminded me of our own experience with a technique that tries to correct residual refractive errors: the light-adjustable lens. (medscape.com)
  • People with refractive error frequently have blurry vision. (wikipedia.org)
  • ABSTRACT The occurrence of corneal ectasia after photorefractive keratectomy is a rare but serious complication of refractive surgery. (bvsalud.org)
  • By controlling the irradiation dose and spatial irradiance profile, the refractive power of the light-adjustable IOL is modified to add or subtract spherical power, or to eliminate astigmatic error. (medscape.com)
  • Debridement of the haze with intraoperative MMC without PTK was tried to avoid a refractive 'surprise. (ophthalmologytimes.com)
  • Current O-PCMs, such as Ge-Sb-Te (GST), exhibit large contrast of both refractive index (Δ n ) and optical loss (Δ k ), simultaneously. (nature.com)
  • These exotic materials exhibit a large refractive index shift across multiple wavebands through a reversible phase transition (amorphous-to-crystalline) initiated through external energy stimuli. (spiedigitallibrary.org)
  • Treatment with 200 mg/kg bodyweight C-PC (Group III) transcriptionally regulated the instability of the expression of these genes, thus ensuring C-PC is a prospective anticataractogenic agent that probably delays the onset and progression of cataractogenesis induced by sodium selenite. (molvis.org)
  • Fig. Y 2 SiO 5 crystal cavity (6 mm long) transmission spectrum (red trace), absorption spectrum (black trace) and refractive index spectrum (blue trace) around an 18 MHz spectral hole. (lu.se)
  • A sharp decay of the signal is induced by the absorption of the light and the signal slowly rise back to its original value through different interactions. (lu.se)
  • in which he presented 3 exciting new refractive technologies that he is working on-the Raindrop inlay, the LensGen accommodating IOL, and refractive index shaping of lenses in vivo. (aao.org)
  • Holotomography can determine the morphological, chemical, and mechanical properties of cells, including the presence of viral infection which is associated with unusually high refractive index values. (news-medical.net)
  • where Δ n and Δ k denote the real and imaginary parts of refractive index change induced by the phase transition, respectively. (nature.com)
  • The refractive index of an embedded PCM thin film is modulated through an amorphous-to-crystalline phase transition induced through thermal stimulus. (spiedigitallibrary.org)
  • The broader goals of refractive lensectomy coupled with the need for additional diagnostic tests increase the financial burden on the patient. (crstoday.com)
  • Briefly, DHM is an interferometric imaging technique that measures quantitatively the phase shift induced on the transmitted wave by the observed specimen. (jneurosci.org)
  • I categorize refractive lensectomy patients into two general groups. (crstoday.com)
  • As the saying goes, today's cataract patients are always refractive patients. (medscape.com)
  • E ditor ,-We read with interest the article by Sarhan et al 1 on the effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty. (bmj.com)
  • 2000 ) Effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty. (bmj.com)
  • This class of laser only causes damage if the exposure time exceeds 0.25 s, which approximately corresponds to the time lag of the natural blink reflex (according to DIN EN 60825 1). (aerzteblatt.de)
  • This article reports the findings and methodology of a project in which 17 laboratories participated in three interlaboratory exercises to assess the performance of refractive index, micro X-ray Fluorescence Spectroscopy (µXRF), and Laser Induced Breakdown Spectroscopy (LIBS) data for the forensic comparison of glass samples. (ojp.gov)
  • As the transverse profile of the laser intensity in the focal spot has a maximum in the centre, the refractive index will have a maximum here. (lu.se)
  • The plasma medium will act as a positive lens induced by the laser itself as it travels through the gas. (lu.se)
  • In a process called "phase wrapping," a convex lens is reduced by the femtosecond laser to a thin layer of approximately 50 μm in thickness, creating multiple refractive zones. (medscape.com)
  • We are going to use the slow light effect induced by spectral hole burning to stabilize the laser frequency. (lu.se)
  • This leads to a relativistic mass increase of the electrons, and in turn a decrease of the refractive index of the plasma (through the plasma frequency). (lu.se)
  • Dr Waring presented a number of procedures done in the model eye, during which the refractive index was changed by about 3.5 diopters. (medscape.com)
  • Other terminology include anisometropia, when the two eyes have unequal refractive power, and aniseikonia which is when the magnification power between the eyes differ. (wikipedia.org)
  • A case is presented in the Journal of Cataract & Refractive Surgery which describes a patient who had his spectacles shattered by the catapulting metal end of a bungee cord - resulting in corneal lacerations from the broken glass. (improbable.com)
  • chance of vision loss is 1% if the patient is considered a good candidate for refractive surgery preoperatively. (msdmanuals.com)
  • Although the patient reported an ongoing cough and pneumonialike symptoms, a severe atypical pneumonia that was refractive to antibacterial and antimycotic treatment was diagnosed for the first time during this hospital treatment. (cdc.gov)
  • Using vectorial diffraction simulations, the system performance was characterized based on illumination angle and polarization, signal to noise ratio, and refractive index of the tertiary objective immersion. (arxiv.org)
  • Consequently, the phase signal provides information about cell morphology (and volume) and the intracellular refractive index whose value is related to the amount of nonaqueous material (essentially protein content) present in the cell ( Barer, 1953 ). (jneurosci.org)
  • The cell membrane and organelles can be imaged at a resolution of 100 nm, with no photobleaching or phototoxicity-induced damage to cells or interference with normal molecular activities. (news-medical.net)
  • When dealing with increasing environmental concerns associated with water, air and soil pollution, as well as climate change induced by human activities, accurate assessment of the state of the environment is a prerequisite for undertaking any course of action towards improvement. (epa.gov)
  • The correspondence between the linear integral transform and the ray-transfer matrix of a diffraction-free first-order optical system is used to describe the ray trajectory and to study the point spread function (PSF) in an active GRIN microlens characterized by a complex refractive index. (spie.org)
  • During tempering process, the non-homogenous heating or rapid cooling can induce localized strain in the glass leading to birefringence (or optical anisotropy) phenomenon, a result of the photoelastic effect. (glassonweb.com)
  • Transformation media theory, which steers waves in solids via an effective geometry induced by a refractive material (Fermat's principle of least action), provides a means of controlling vibrations and elastic waves beyond the traditional dissipative structures regime. (researchgate.net)
  • Frustration and weariness caused by the constant effort to achieve clear vision and coordinate the two eyes were commonly detected, although the role of vision was difficult to pinpoint because of the many factors involved in inducing this condition. (cdc.gov)
  • Steroid-induced IOP elevation typically occurs within a few weeks of beginning steroid therapy. (medscape.com)
  • In a study conducted at our clinic, [ 2 ] 96% of 21 eyes were within ± 0.50 diopter of the intended refractive outcome and 81% within ± 0.25 diopter 1 year after implantation and postoperative light-induced fine tuning. (medscape.com)
  • For samples that originated from the same source, the overall correct association rate was greater than 92 percent for each of the three techniques (refractive index, µXRF, and LIBS). (ojp.gov)
  • Hepatocellular Carcinoma and Hepatitis C Virus Treatments This review elucidates the pathogenesis of chronic HCV-induced hepatocellular carcinoma, discussing the relationship between hepatic carcinogenesis and viral eradication by antivirals. (medscape.com)
  • Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error. (nih.gov)
  • There is uneven distribution of refractive indexes within the tissue, resulting in light refraction and reflection events. (news-medical.net)
  • This design induces Fresnel reflections and a reduced effective aperture, thus impacting the resolution and light efficiency of the system. (arxiv.org)
  • Receive a complimentary subscription to the Journal of Refractive Surgery , the highest-rated journal in the refractive surgery subspecialty, in print and online. (isrs.org)
  • Thought you might appreciate this item(s) I saw in Journal of Cataract & Refractive Surgery. (lww.com)
  • Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity. (bvsalud.org)
  • Asimetrías en la topografía e índice de refracción de la superficie corneal que afectan a la agudeza visual. (bvsalud.org)