Post-LASIK ectasia

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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. [1]

Keratoconus corneal disease characterized by structural changes within the cornea causing it to thin and change, leading to a protruding conical shape

Keratoconus (KC) is a disorder of the eye which results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea.

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. The 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 eye surgery

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.

Contents

Risk factors

Before corneal refractive surgery such as LASIK, SMILE, and PRK, people must be examined for possible risk factors such as keratoconus. [2]

Abnormal corneal topography compromises of keratoconus, pellucid marginal degeneration, or forme fruste keratoconus with an I-S value of 1.4 or more [3] is the most significant risk factor. Low age, low residual stromal bed (RSB) thickness, low preoperative corneal thickness, and high myopia are other important risk factors. [4] [5]

Corneal topography Cornea

Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive medical imaging technique for mapping the surface 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.

Pellucid marginal degeneration human disease

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.

In medicine, a forme fruste is an atypical or attenuated manifestation of a disease or syndrome, with the implications of incompleteness, partial presence or aborted state. The context is usually one of a well defined clinical or pathological entity, which the case at hand almost — but not quite — fits.

Treatments

Treatment options include contact lenses, [6] [7] intrastromal corneal ring segments, custom topography-guided transepithelial PRK combined with corneal collagen cross-linking, [8] or corneal transplant.

Corneal collagen cross-linking surgical treatment for corneal ectasia

Corneal collagen 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.

When cross-linking is performed only after the cornea becomes distorted, vision remains blurry even though the disease is stabilised. As a result, combining corneal collagen cross-linking with LASIK ('LASIK Xtra') aims to strengthen the cornea at the point of surgery and may be useful in cases where a very thin cornea is expected after the LASIK procedure. [9] This would include cases of high spectacle power and people with thin corneas before surgery. Definitive evidence that the procedure can reduce the risk of corneal ectasia will only become available a number of years later as corneal ectasia, if it happens, usually occurs in the late post-operative period. Some study show that combining LASIK with cross-linking adds refractive stability to hyperopic treatments and may also do the same for very high myopic treatments. [9] [10]

In 2016, the FDA approved the KXL system and two photoenhancers for the treatment of corneal ectasia following refractive surgery. [11]

Related Research Articles

Radial keratotomy

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.

Refractive surgery medical specialty

Refractive eye surgery is an 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 and astigmatism, as well as degenerative disorders like keratoconus.

Phakic intraocular lens

A phakic intraocular lens (PIOL) is a special kind of intraocular lens that is implanted surgically into the eye to correct myopia (nearsightedness). It is called "phakic" because the eye's natural lens is left untouched. Intraocular lenses that are implanted into eyes after the eye's natural lens has been removed during cataract surgery are known as pseudophakic.

Intrastromal corneal ring segment

An intrastromal corneal ring segment (ICRS) is a small device implanted in the eye to correct vision. The procedure involves an ophthalmologist who makes a small incision in the cornea of the eye and inserts two crescent or semi-circular shaped ring segments between the layers of the corneal stroma, one on each side of the pupil. The embedding of the two rings in the cornea is intended to flatten the cornea and change the refraction of light passing through the cornea on its way into the eye.

Emmetropia is the state of vision where a faraway object at infinity is in sharp focus with the eye lens in a neutral or relaxed state. This condition of the normal eye is achieved when the refractive power of the cornea and the axial length of the eye balance out, which focuses rays exactly on the retina, resulting in perfect vision. A human eye in a state of emmetropia requires no corrective lenses; the vision scores well on a visual acuity test. For example, on a Snellen chart test, emmetropic eyes score at "6/6"(m) or "20/20"(ft) vision, meaning that at a distance of 20 ft they see as well as a normal eye at a distance of 20 ft. Either myopic (near-sighted) eyes or hyperopic (far-sighted) eyes would score worse, e.g. 20/40. A person with exceptionally acute vision might score at 20/15.

Professor Dan Z. Reinstein, MD, MA (Cantab), FRCSC, DABO, FRCOphth, FEBO, Cert LRS, PGDip CRS is a specialist ophthalmic surgeon in the UK and is a board-certified registered specialist ophthalmologist in the USA, Canada and the UK, specialising in the field of refractive surgery. He is medical director of the London Vision Clinic and a voluntary faculty member as Professor of Ophthalmology at Columbia University College of Physicians and Surgeons as well as a Visiting Professor at the University of Ulster, UK and Professeur Associé at the Faculty of Medicine, Sorbonne Université, Paris, France.

Mark Cohen (surgeon) Canadian ophthalmologist

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.

Gholam A. Peyman is an 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, developed by Australian ophthalmologist Noel Alpins, 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 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.

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 Swiss eye surgeon and researcher

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:

PiXL is a modern non-invasive non-surgical vision correction procedure.

References

  1. "Ectasia After LASIK". American Academy of Ophthalmology.
  2. Finn, Peter (20 December 2012). "Medical Mystery: Preparation for surgery revealed cause of deteriorating eyesight". The Washington Post.
  3. Rabinowitz, YS; McDonnell, PJ (1989). "Computer-assisted corneal topography in keratoconus". Refractive & Corneal Surgery. 5 (6): 400–8. PMID   2488838.
  4. Kohlhaas, M; Spoerl, E; Schilde, T; Unger, G; Wittig, C; Pillunat, LE (February 2006). "Biomechanical evidence of the distribution of cross-links in corneas treated with riboflavin and ultraviolet A light". Journal of Cataract and Refractive Surgery. 32 (2): 279–83. doi:10.1016/j.jcrs.2005.12.092. PMID   16565005.
  5. Randleman, JB; Banning, CS; Stulting, RD (January 2007). "Corneal ectasia after hyperopic LASIK". Journal of Refractive Surgery. 23 (1): 98–102. doi:10.3928/1081-597X-20070101-17. PMID   17269252.
  6. 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 .
  7. 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.
  8. Lam, Kay; Rootman, Dan B.; Lichtinger, Alejandro; Rootman, David S. (6 January 2013). "Post-LASIK ectasia treated with intrastromal corneal ring segments and corneal crosslinking". Digital Journal of Ophthalmology : DJO. 19 (1): 1–8. doi:10.5693/djo.02.2012.10.001 (inactive 2019-06-23). ISSN   1542-8958. PMC   3689440 . PMID   23794955.
  9. 1 2 Stephenson, Michelle (2014). "LASIK Xtra: Is It for Everyone?". Review of Ophthalmology. Jobson Medical Information LLC.
  10. Kanellopoulos, AnastasiosJohn; Pamel, GregoryJ (2013). "Review of current indications for combined very high fluence collagen cross-linking and laser in situ keratomileusis surgery". Indian Journal of Ophthalmology. 61 (8): 430–2. doi:10.4103/0301-4738.116074. PMC   3775081 . PMID   23925331.
  11. "Highlights of Prescribing Information: PHOTREXA VISCOUS (riboflavin 5'-phosphate in 20% dextran ophthalmic solution) 0.146% for topical ophthalmic use PHOTREXA (riboflavin 5'-phosphate ophthalmic solution) 0.146% for topical ophthalmic use For use with the KXL® System" (PDF). U.S. Food and Drug Administration. pp. 5–14.