Related Research Articles
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.
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.
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 femtosecond laser or a microkeratome to create a corneal flap to expose the corneal stroma and then an excimer laser to reshape the corneal stroma in order to improve visual acuity.
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.
A phakic intraocular lens (PIOL) is an intraocular lens that is implanted surgically into the eye to correct refractive errors without removing the natural lens. Intraocular lenses that are implanted into eyes after the eye's natural lens has been removed during cataract surgery are known as pseudophakic.
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue. When the entire cornea is replaced it is known as penetrating keratoplasty and when only part of the cornea is replaced it is known as lamellar keratoplasty. Keratoplasty simply means surgery to the cornea. The graft is taken from a recently deceased individual with no known diseases or other factors that may affect the chance of survival of the donated tissue or the health of the recipient.
Corneal cross-linking (CXL) with riboflavin (vitamin B2) and UV-A light is a surgical treatment for corneal ectasia such as keratoconus, PMD, and post-LASIK ectasia.
A scleral lens, also known as a scleral contact lens, is a large contact lens that rests on the sclera and creates a tear-filled vault over the cornea. Scleral lenses are designed to treat a variety of eye conditions, many of which do not respond to other forms of treatment.
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.
Keratoglobus is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to become extremely thin and change to a more globular shape than its normal gradual curve. It causes corneal thinning, primarily at the margins, resulting in a spherical, slightly enlarged eye.
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.
Mark Cohen is a Canadian laser eye surgeon who practices in Montreal and Toronto. In 2001, he and Avi Wallerstein founded LASIK MD, Canada's largest provider of laser refractive surgery. As of 2013, LASIK MD performs over sixty percent of all laser vision correction procedures in Canada. He is one of only 14 certified C-LASIK instructors in North America.
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.
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.
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.
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 hydrops is an uncommon complication seen in people with advanced keratoconus or other corneal ectatic disorders, and is characterized by stromal edema due to leakage of aqueous humor through a tear in Descemet's membrane. Although a hydrops usually causes increased scarring of the cornea, occasionally it will benefit a patient by creating a flatter cone, aiding the fitting of contact lenses. Corneal transplantation is not usually indicated during corneal hydrops.
Terrien marginal degeneration is a noninflammatory, unilateral or asymmetrically bilateral, slowly progressive thinning of the peripheral corneal stroma.
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:
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.
References
- ↑ "Corneal ectatic disorders (keratoconus and pellucid marginal degeneration)". AAO ONE Network. American Academy of Ophthalmology.
- ↑ Weissman, Barry A; Yeung, Karen K (2019-05-30). "Keratoconus". Medscape.
- ↑ Wallang, B S; Das, S (28 June 2013). "Keratoglobus". Eye. 27 (9): 1004–1012. doi:10.1038/eye.2013.130. PMC 3772364 . PMID 23807384.
- ↑ Rasheed, Karim; Rabinowitz, Yaron (2018-12-24). "Pellucid Marginal Degeneration". Medscape .
- ↑ "Ectasia After LASIK". American Academy of Ophthalmology.
- ↑ "Terrien marginal degeneration". American Academy of Ophthalmology.
- ↑ Marsack, Jason D.; Parker, Katrina E.; Applegate, Raymond A. (December 2008). "Performance of Wavefront-Guided Soft Lenses in Three Keratoconus Subjects". Optometry and Vision Science. 85 (12): E1172–E1178. doi:10.1097/OPX.0b013e31818e8eaa. PMC 2614306 . PMID 19050464.
- ↑ Marsack, JD; Parker, KE; Niu, Y; Pesudovs, K; Applegate, RA (November 2007). "On-eye performance of custom wavefront-guided soft contact lenses in a habitual soft lens-wearing keratoconic patient". Journal of Refractive Surgery. 23 (9): 960–4. doi:10.3928/1081-597x-20071101-18. PMID 18041254.
- ↑ Avni-Zauberman, N; Rootman, DS (November 2014). "Cross-linking and intracorneal ring segments--review of the literature". Eye & Contact Lens. 40 (6): 365–70. doi:10.1097/icl.0000000000000091. PMID 25320956. S2CID 38858189.