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Near-sightedness, also known as short-sightedness and myopia, is an eye disorder where light focuses in front of, instead of on, the retina. This causes distant objects to be blurry while close objects appear normal. Other symptoms may include headaches and eye strain. Severe near-sightedness is associated with an increased risk of retinal detachment, cataracts, and glaucoma.
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.
Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, instead of on, the retina wall due to insufficient accommodation by the lens. Small amount of 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 asthenopic symptoms while constant reading. Some hypermetropes can see clear at distance, but near vision may be blurred due to insufficient accommodation. For this reason, this defect is referred as far-sightedness. 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 astigmatism. 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. For most people, LASIK provides a long-lasting alternative to eyeglasses or contact lenses.
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.
Radial keratotomy (RK) is a refractive surgical procedure to correct myopia (nearsightedness) that was developed in 1974, by Svyatoslav Fyodorov, a Russian ophthalmologist. It has been largely supplanted by newer operations, such as photorefractive keratectomy, LASIK, Epi-LASIK and the phakic intraocular lens. Approximately 10% of all practicing ophthamologists in the United States have performed several hundred thousand RK procedures.
Refractive eye surgery is non-essential 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. Successful refractive eye surgery can reduce or cure common vision disorders such as myopia, hyperopia, presbyopia and astigmatism.
Intraocular lens (IOL) is a lens implanted in the eye as part of a treatment for cataracts or myopia. If someone has a natural lens in the eye it is known as phakic and if someone has an artificial lens in the eye it is known as pseudophkic or false lens. These are implanted during cataract surgery, after the cloudy eye's natural lens 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 (nearsightedness). In other words this is an alternative to Lasik.
Orthokeratology (also referred to as Ortho-K, OK, Overnight Vision Correction, Corneal Refractive Therapy , Accelerated Orthokeretology, Cornea Corrective Contacts, Eccentricity Zero Molding and Gentle Vision Shaping System refers to the use of gas-permeable contact lenses that temporarily reshape the cornea to reduce refractive errors such as myopia, hyperopia and astigmatism.
Corneal cross-linking with riboflavin (vitamin B2) and UV-A light is a surgical treatment for corneal ectasia such as keratoconus, PMD, and post-LASIK ectasia.
Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina, due to a variation in the optical power of the eye for light coming from different directions. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at night. Astigmatism usually occurs at birth, but can sometimes develop later in life. If it occurs in early life and is left untreated, it can result in amblyopia.
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.
Pellucid marginal degeneration (PMD), is a degenerative corneal condition, often confused with keratoconus. It typically presents with painless vision loss affecting both eyes. Rarely, it may cause acute vision loss with severe pain due to perforation of the cornea. It is typically characterized by a clear, bilateral thinning (ectasia) in the inferior and peripheral region of the cornea, although some cases affect only one eye. The cause of the disease remains unclear.
Peter S. Hersh is an American ophthalmologist 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.
The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism.
Emil William Chynn is a Chinese-American LASEK surgeon, author, researcher, and media personality. He owns the only laser vision correction center in the US specializing in Advanced Surface Ablation, which unlike LASIK is a newer, safer way to correct refractive errors that does not involve cutting a flap into the cornea. Dr. Chynn has been featured in the New York Times, Wall Street Journal, on CNN and Discovery Channel, in Time Magazine online, as well as on ABC, NBC, CBS, and Fox News for LASEK as well as platinum "Eye Jewelry" and corneal tattoos. Dr. Chynn has also appeared on the Howard Stern Show as one of NYC's most eligible bachelors, as well on "Millionaire Matchmaker" with abrasive reality TV matchmaker Patti Stanger.
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.
Corneal ectatic disorders or corneal ectasia are a group of uncommon, noninflammatory, eye disorders characterised by bilateral thinning of the central, paracentral, or peripheral cornea.
Farhad Hafezi is a prominent Swiss eye surgeon and researcher. Hafezi first gained recognition as a leading retina researcher in 1994, having been the first to discover a gene responsible for light-induced retinal degeneration. However, he changed his research focus to the cornea in 2003, and it is this work, particularly on corneal collagen cross-linking (CXL), which he helped pioneer, and advanced laser refractive surgery that he is internationally known for today. Hafezi's current clinical and laboratory research is focused on gaining a better understanding of the cornea. His research group at the University of Zurich has three main research foci:
Contoura Vision is a topography guided laser technology used to correct refractive error and thereby decreasing or eliminating dependency on glasses or contact lenses. Contoura Vision technology reduces side effects that linked with laser procedures like LASIK and SMILE. It was FDA approved in the US in 2016. The Contoura Vision method provides a measurement of 22,000 points as compared to 200 points provided by wave front-guided LASIK method. The imperfections in the cornea are recorded and is then corrected with the help of laser.
References
- 1 2 "PiXL Vision Correction Procedure Toronto - Clearview Vision Institute".
- ↑ "PiXL". Kingston Medical Centre.
- ↑ Kanellopoulos, John (1 April 2014). "Novel myopic refractive correction with transepithelial very high-fluence collagen cross-linking applied in a customized pattern: early clinical results of a feasibility study". Clinical Ophthalmology. 8: 697–702. doi:10.2147/OPTH.S59934. PMC 3984063 . PMID 24741289.
- 1 2 Lim, Wee Kiak; Soh, Zhi Da; Choi, Harold Kah Yen; Theng, Julian Thiam Siew (1 June 2017). "Epithelium-on photorefractive intrastromal cross-linking (PiXL) for reduction of low myopia". Clinical Ophthalmology. Volume 11: 1205–1211. doi:10.2147/OPTH.S137712. PMC 5499923 .
|volume=has extra text (help) - ↑ "PiXL - EyeWiki". eyewiki.aao.org.
- ↑ "Say Hello To PiXL™ — The New Non-Invasive Vision Improvement Procedure".