icce2007.info

Refractive surgery

Refractive surgery

These procedures do not require a partial thickness cut into the stroma. Therefore, keratoconus is a contraindication to refractive surgery.

This can include various methods of surgical remodeling of the cornea or cataract surgery. Surface ablation methods differ only in the way the epithelial layer is handled. The Council for Refractive Surgery Quality Assurance - an independent, nonprofit, patient/consumer health organization that provides information about refractive surgery and certifies LASIK surgeons - considers surgeons to have met the US national norms if 90% of their patients achieve 20/40 vision or better and 65% of their patients achieve 20/20 vision or better, with less than approximately 3% of their refractive surgery patients experiencing a surgery induced complication at six months after surgery, and less than 0.5% being serious complications requiring extensive maintenance or invasive treatment. Many people with myopia are able to read comfortably without eyeglasses.

Myopes considering refractive surgery are advised that this may be a disadvantage after the age of 40 when the eyes become presbyopic and lose their ability to accommodate or change focus. While refractive surgery is becoming more affordable and safe, it may not be recommended for everybody. Successful refractive eye surgery can reduce or cure common vision disorders such as myopia, hyperopia and astigmatism. According to surveys of members of the American Society of Cataract and Refractive Surgery, approximately 948,266 refractive surgery procedures were performed in the United States during 2004 and 928,737 in 2005. The first experimental studies about refractive surgery were published in 1896 by Lendeer Jans Lans, an ophthalmology teacher in Holland, where he developed a theoretical work proposing penetrating corneal cuts to correct astigmatism.

Swinger in 1986 (keratomileusis without freezing), it was still a relatively imprecise technique. Meanwhile, experiments in 1970 using a xenon dimer and in 1975 using noble gas halides resulted in the invention of a type of laser called an excimer laser. While this form of surgery was later improved by Dr.

In 1983, scientist Stephen Trokel of Columbia University in collaboration with Srinivasan performed the first Photorefractive Keratectomy (PRK) or keratomileusis in situ (without separation of corneal layer) in Germany. He practiced radial cuts in the cornea to correct effects by up to 6 diopters, but this procedure was soon rejected by the medical community because of the high rate of corneal degeneration. In 1963, in the Barraquer ophthalmologic clinic (Bogotá,Colombia) Ignacio Barraquer developed the first proficient refractive surgery technique called keratomileusis, meaning corneal reshaping (from the Greek Kerato: cornea and Mileusis: to sculpt).

Peyman, MD on June 20, 1989, US Patent #4,840,175, METHOD FOR MODIFYING CORNEAL CURVATURE , describing the surgical procedure in which a flap is cut in the cornea and pulled back to expose the corneal bed. These early surgeries removed a corneal layer, froze it so it could be manually sculpted in the required shape, and finally reimplanted the layer (Keratomileusis with freezing).

Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. Keratoconus, a progressive thinning of the cornea, is a common corneal disorder.

Keratomileusis allowed correction of not only myopia but also hyperopia. Srinivasan, a scientist of IBM who was using an excimer laser to make microscopic circuits in microchips for informatics equipment, discovered that the excimer could also be used to cut organic tissues with high accuracy without significant thermal damage.

Patients that have medical conditions such as glaucoma or diabetes, uncontrolled vascular disease, autoimmune disease, pregnant women or people with certain eye diseases involving the cornea or retina, are not good candidates for refractive surgery. Furthermore, some people s eye shape may not permit effective refractive surgery without removing excessive amounts of corneal tissue.

Corneal topography, pachymetry and, more recently, Pentacam exams are used to screen for abnormal corneas. The most common methods today use excimer lasers to reshape curvature of the cornea.

The discovery of an effective biological cutting laser, along with the development of computers to control it, allowed new refractive techniques which were previously unavailable. While excimer lasers were initially used for industrial purposes, in 1980, R.

Those considering laser eye surgery should have a full eye examination. Although the risk of complications is decreasing compared to the early days of refractive surgery, . This exposed surface is then ablated to the desired shape with an excimer laser, following which the flap is replaced.

It is believed that additional thinning of the cornea via refractive surgery may contribute to advancement of the disease, that may lead to the need for a corneal transplant. The first patent for LASIK was granted by the US Patent Office to Gholam A.

In 1930 the Japanese ophthalmologist Tsutomu Sato made the first practical attempt to perform such surgery in military pilots. In 1991 Creta University and the Vardinoyannion Eye coined the name LASIK . Excimer laser ablation is done under a partial-thickness lamellar corneal flap. The excimer laser is used to ablate the most anterior portion of the corneal stroma.