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Keratoconus (KC) is a disorder of the eye that results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, irregular astigmatism, and light sensitivity leading to poor quality-of-life. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea.
LASIK or Lasik, commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity.
An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek α- (a-) meaning "without" and στίγμα (stigma), "a mark, spot, puncture".
Radial keratotomy (RK) is a refractive surgical procedure to correct myopia (nearsightedness). It was developed in 1974 by Svyatoslav Fyodorov, a Russian ophthalmologist. It has been largely supplanted by newer, more accurate operations, such as photorefractive keratectomy, LASIK, Epi-LASIK and the phakic intraocular lens.
Refractive surgery is optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea (keratomileusis), lens implantation or lens replacement. The most common methods today use excimer lasers to reshape the curvature of the cornea. Refractive eye surgeries are used to treat common vision disorders such as myopia, hyperopia, presbyopia and astigmatism.
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. 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, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a clear image. Accommodation usually acts like a reflex, including part of the accommodation-vergence reflex, but it can also be consciously controlled. The main ways animals may change focus are:
An autorefractor or automated refractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or contact lenses. This is achieved by measuring how light is changed as it enters a person's eye.
A phoropter or refractor is an ophthalmic testing device. It is commonly used by eye care professionals during an eye examination, and contains different lenses used for refraction of the eye during sight testing, to measure an individual's refractive error and determine their eyeglass prescription. It also is used to measure the patients' phorias and ductions, which are characteristics of binocularity.
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at night. Astigmatism often occurs at birth and can change or develop later in life. If it occurs in early life and is left untreated, it may result in amblyopia.
Franciscus (Franz) Cornelius Donders FRS FRSE was a Dutch ophthalmologist. During his career, he was a professor of physiology in Utrecht, and was internationally regarded as an authority on eye diseases, directing the Netherlands Hospital for Eye Patients. Along with Graefe and Helmholtz, he was one of the primary founders of scientific ophthalmology.
Gene Folk was an American ophthalmologist who specialized in the diagnosis and treatment of strabismus. A charter member of the American Association for Pediatric Ophthalmology and Strabismus, he later served as President of this organization. With Martin Urist, Folk helped found the "Chicago" school of strabismus, whose ideas competed with and stimulated those of Marshall M. Parks, Arthur Jampolsky, and other prominent strabismologists. During the 1950s and 1960s, Urist and Knapp's contributions led to a much improved understanding of so-called A and V "pattern" strabismus, where the amplitude of deviation varies in up- and downgaze.
A cylindrical lens is a lens which focuses light into a line instead of a point, as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to intersection of the surface of the lens and a plane tangent to it along the cylinder's axis. The lens converges or diverges the image in the direction perpendicular to this line, and leaves it unaltered in the direction parallel to its cylinder's axis.
The Alpins Method is a system to plan and analyze the results of refractive surgical procedures, such as laser in-situ keratomileus (LASIK). The Alpins Method is also used to plan cataract/toric intraocular lens (IOL) surgical procedures.
Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). It is a clinical examination used by orthoptists, optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses. The aim is to improve current unaided vision or vision with current glasses. Glasses must also be comfortable visually. The sharpest final refraction is not always the final script the patient wears comfortably.
Anastasios John Kanellopoulos is a Greek-American eye surgeon specializing in corneal transplantation, cornea crosslinking for keratoconus, complicated cataract surgery and complicated glaucoma. Widely known for research and clinical contributions in micro-incision cataract, customized laser refractive surgery and corneal cross-linking propagation and most innovations, reducing corneal transplants for advanced keratoconus.
Robert M. Schertzer is a Canadian ophthalmologist with a subspecialty in glaucoma treatment. He currently serves as the Clinical Associate Professor of Ophthalmology and Visual Sciences at the University of British Columbia.
A trial frame is a tool used by ophthalmic professionals like ophthalmologists and optometrists. It is basically an adjustable spectacle frame with multiple cells, used to hold corrective lenses, and other accessories in subjective refraction and retinoscopy.
The Jackson cross cylinder (JCC) is an instrument used by ophthalmologists, orthoptists and optometrists in their routine eye examination, particularly in determination of corrective lens power in patients with astigmatism. It is also used for testing near point of the eye.
Stokes lens also known as variable power cross cylinder lens is a lens used to diagnose a type of refractive error known as astigmatism.
References
- 1 2 3 4 5 6 "DR. EDWARD JACKSON".
- 1 2 3 4 Newell, F. W. (April 1988). "Edward Jackson, MD--a historical perspective of his contributions to refraction and to ophthalmology". Ophthalmology. 95 (4): 555–558. doi:10.1016/s0161-6420(88)33158-1. ISSN 0161-6420. PMID 3050696.
- 1 2 3 "Nine Trailblazers Who Championed Ophthalmology's Independence in Medicine". diplomatedigest. 5 July 2018.
- ↑ Ferrer-Altabás, Sara; Thibos, Larry; Micó, Vicente (14 March 2022). "Astigmatic Stokes lens revisited". Optics Express. 30 (6): 8974–8990. Bibcode:2022OExpr..30.8974F. doi: 10.1364/OE.450062 . ISSN 1094-4087. PMID 35299337.
- ↑ Lichter, Paul R. (1 June 1994). "Honoring the History of the Edward Jackson Memorial Lecture: The L Edward Jackson Memorial Lecture. Part 1". American Journal of Ophthalmology. 117 (6): 699–705. doi:10.1016/S0002-9394(14)70313-7. ISSN 0002-9394. PMID 8198154.