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Myopia, also known as near-sightedness and short-sightedness, is an eye disease where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma.
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK.
Far-sightedness, also known as long-sightedness, hypermetropia, and hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead of on, the retina due to insufficient accommodation by the lens. Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision. But, due to this accommodative effort for distant vision, people may complain of eye strain during prolonged reading. If the hypermetropia is high, there will be defective vision for both distance and near. People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus. Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older.
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.
Photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (LASEK) are laser eye surgery procedures intended to correct a person's vision, reducing dependency on glasses or contact lenses. LASEK and PRK permanently change the shape of the anterior central cornea using an excimer laser to ablate a small amount of tissue from the corneal stroma at the front of the eye, just under the corneal epithelium. The outer layer of the cornea is removed prior to the ablation.
A microkeratome is a precision surgical instrument with an oscillating blade designed for creating the corneal flap in LASIK or ALK surgery. The normal human cornea varies from around 500 to 600 μm in thickness; and in the LASIK procedure, the microkeratome creates an 83 to 200 μm thick flap. The microkeratome uses an oscillating blade system, which has a blade that oscillates horizontally as the blade travels vertically for a precise cut. This piece of equipment is used all around the world to cut the cornea flap. The microkeratome is also used in Descemet's stripping automated endothelial keratoplasty (DSAEK), where it is used to slice a thin layer from the back of the donor cornea, which is then transplanted into the posterior cornea of the recipient. It was invented by Jose Barraquer and Cesar Carlos Carriazo in the 1950s in Colombia.
Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.
Keratomileusis, from Greek κέρας and σμίλευσις, or corneal reshaping, is the improvement of the refractive state of the cornea by surgically reshaping it. It is the most common form of refractive surgery. The first usable technique was developed by José Ignacio Barraquer, commonly called "the father of modern refractive surgery."
Refractive surgery is an 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.
Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive medical imaging technique for mapping the anterior curvature of the cornea, the outer structure of the eye. Since the cornea is normally responsible for some 70% of the eye's refractive power, its topography is of critical importance in determining the quality of vision and corneal health.
José Ignacio Barraquer Moner was a Spanish ophthalmologist and inventor born in Barcelona who did most of his life's work in Bogotá, Colombia.
Automated lamellar keratoplasty (ALK), also known as keratomileusis in situ, is a non-laser lamellar refractive procedure used to correct high degree refractive errors. This procedure can correct large amounts of myopia and hyperopia. However, the resultant change is not as predictable as with other procedures.
D. Jackson Coleman is a professor of clinical ophthalmology at NewYork-Presbyterian Hospital at The Edward S. Harkness Eye Institute of Columbia University. He is the former John Milton McLean Professor of Ophthalmology and chairman emeritus at Weill Cornell Medical Center where he served as chairman from 1979 to 2006. His specialties are retinal diseases and ultrasound, working with patients at Columbia University Medical Center. Coleman is also engaged in research involving ultrasound, which he has pursued throughout his career with colleague Ronald Silverman in the Department of Ophthalmology at the Columbia University Medical Center.
Stephen Updegraff, M.D., FACS is an American refractive surgeon best known for his early involvement in, and contributions to, LASIK. He is a Fellow of the American College of Surgeons, a board-certified member of the American Board of Ophthalmology, a founding member of the American College of Ophthalmic Surgeons, and a member of the International Society of Refractive Surgery, the American Academy of Ophthalmology, the American Society of Cataract and Refractive Surgery, and the Pine Ridge Eye Study Society. Updegraff currently serves as the medical director of Updegraff Vision in St. Petersburg, Florida.
Diffuse lamellar keratitis (DLK) is a sterile inflammation of the cornea which may occur after refractive surgery, such as LASIK. Its incidence has been estimated to be 1 in 500 patients, though this may be as high as 32% in some cases.
Gholam A. Peyman is an Iranian American ophthalmologist, retina surgeon, and inventor. He is best known for his invention of LASIK eye surgery, a vision correction procedure designed to allow people to see clearly without glasses. He was awarded the first US patent for the procedure in 1989.
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.
Peter S. Hersh is an American ophthalmologist, researcher, and specialist in LASIK eye surgery, keratoconus, and diseases of the cornea. He co-authored the article in the journal Ophthalmology that presented the results of the study that led to the first approval by the U.S. Food and Drug Administration (FDA) of the excimer laser for the correction of nearsightedness in the United States. Hersh was also medical monitor of the study that led to approval of corneal collagen crosslinking for the treatment of keratoconus. He was the originator, in 2015, of CTAK for keratoconus, patent holder, and co-developer.
Post-LASIK ectasia is a condition similar to keratoconus where the cornea starts to bulge forwards at a variable time after LASIK, PRK, or SMILE corneal laser eye surgery. However, the physiological processes of post-LASIK ectasia seem to be different from keratoconus. The visible changes in the basal epithelial cell and anterior and posterior keratocytes linked with keratoconus were not observed in post-LASIK ectasia.
Noel Alpins is an Australian ophthalmologist who developed the Alpins method of astigmatism analysis used in refractive, corneal, and cataract surgery, used in the research of LASIK.
References
Cassin B, Solomon S (1990). Dictionary of Eye Terminology. Gainesville, Florida: Triad Publishing Company.
