Dictionary
a refractive surgery procedure that reshapes the cornea
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Wikipedia
LASIK, an acronym for Laser- in situ In Situ KeratomileusisKeratomileusis, is a form of refractive surgeryrefractive laser eye surgery procedure performed by ophthalmologists intended for correcting the vision in order to reduce a person's dependency on corrective devices, such as glasses or contact lenses. The procedure is usually a preferred alternative to photorefractive keratectomy, PRK, as it requires less time for full recovery, and the patient experiences less pain overall.
History of LASIK - The concept of LASIK surgery was made possible by Dr JoseBarraquer, who around 1970 developed the first microkeratome, to cut thin corneal flaps and alter corneal shape, in a procedure called keratomileusis. LASIK surgery was developed in 1990 by Dr. Lucio Buratto (Italy) and Dr. Ioannis Pallikaris (Greece) as a melding of two prior techniques, keratomileusis and photorefractive keratectomy. It quickly became popular due to its improved precision and lower frequency of complications compared with those techniques.laservision.co.thIn 1991, LASIK was performed for the first time in the United States by Drs. Stephen Brint and Stephen Slade !brintvision.joneseyecenters.co m. In Germany the two Neuhann brothers - Thomas and Tobias - from Munich treated 1991 the first German Lasik patients with an automated microkeratome successfully.
Surgical procedure -
Pre-operative - Prior to the surgery, the surface of the patient's corneas are examined with a computer-controlled scanning device to determine their exact shape. Using low-power lasers, it creates a topographic map of the cornea. This process also detects astigmatism and other irregularities in the shape of the cornea. Using this information, the surgeon calculates the amount and locations of corneal tissue to be removed during the operation. The patient is typically prescribed an antibiotic to start taking beforehand, to minimize the risk of infection after the procedure.
The operation - The operation is performed with the patient awake and functional, however, the patient is typically given a mild sedative (such as valium) and anesthetic eye drops. The surgeon operates the lasers, which make all of the incisions. A computer system tracks the patient's eye position 4,000 times per second, redirecting laser pulses for precise placement. A flap is cut in the cornea using a blade (called a microkeratome) or a femtosecond laser. A hinge is left at one end of this flap. The flap is folded back revealing the stroma, the middle section of the cornea. Then an excimer laser (193 nm) is used to remodel the corneal stroma. The laser vaporizes tissue without causing damage to adjacent stroma in a finely controlled manner. The layers of tissue removed are tens of micrometres wide.
Complications - is a common and relatively minor post-LASIK complication.]]Although relatively uncommon, complications due to LASIK do occur. The following are some of the more frequently reported complications of LASIK complicatedeyes.org: Dry eyes Over/undercorrection Visual acuity fluctuation Halo/Starbursts around light sources Light sensitivity Ghosts/double vision Wrinkles in flap (striae) Decentered ablation Debris/growth under flap Thin/buttonhole flap Induced astigmatism Epithelium erosion Flap complications (such as displaced flaps or folds in the flaps that requiring repositioning, diffuse lamellar keratitis, and epithelial ingrowth) are relatively common in lamellar corneal surgeries lasikinstitute.org, but rarely lead to permanent visual acuity loss; the incidence of these microkeratome-related complications decreases with increased physician experience ncbi.nlm.nih.gov ncbi.nlm.nih.gov.A slipped flap (when the corneal flap detaches from the rest of the cornea) is one of the most common complications. The chances of this are greatest immediately following surgery, so patients are typically recommended to go home and sleep, to let the flap heal.Although LASIK technology is improving at a rapid pace, a large body of conclusive evidence on the chances of long-term complications is not yet in place. Also, there is a small chance of complications, such as slipped flap, corneal infection, haziness, halo or glare, amongst others. The procedure is irreversible. Infection under the corneal flap is possible. It is also possible that the patient has a genetic condition that causes the cornea to thin out following surgery. While this is screened for in the pre-op exam, it is possible in rare cases (about 1 in 5,000) for the condition to remain dormant until later in life (the mid-40s). If this occurs, the patient will require a corneal transplant.Although the cornea is usually thinner after LASIK due to the removal of part of the stroma, refractive surgeons strive to maintain a minimum thickness in order not to not structurally weaken the cornea. Decreased atmospheric pressure at higher altitudes has not been shown to be extremely dangerous to the eyes of LASIK patients, however, some mountain climbers have experienced a myopic shift at extreme altitudes ncbi.nlm.nih.gov ncbi.nlm.nih.gov. Although there are no published reports documenting diving related complications after LASIK scuba-doc.com, urban legends that describe eyes that have popped open while scuba diving still persist.
Factors affecting the surgery - The cornea is typically avascular in that it must be transparent to function normally. Its cells absorb oxygen from the tearstear film. Low oxygen-permeable contact lenses reduce the cornea's absorption of oxygen which sometimes results in the growth of blood vessels into the cornea - a process known as ''corneal neovascularization''. This can cause a mild increase in inflammation and healing time, and some discomfort during the surgery due to augmented bleeding. Although some contact lenses, notably modern RGP and soft silicone hydrogel lenses, are made of materials with higher oxygen permeability that help reduce the risk of corneal neovascularization, patients considering LASIK are cautioned to avoid overwearing their lenses. It is usually recommended that contact lens use is discontinued several days to weeks prior to the LASIK procedure.A 2004 Wake Forest University study found that Lasik results are affected by heat and humidity, both during the procedure and in the two weeks preceding surgeryncbi.nlm.nih.gov.
Safety and efficacy - The reported figures for safety and efficacy are widely open to interpretation. In 2003, the Medical Defence Union, the largest insurer for doctors in the United Kingdom, reported a 166% increase in claims involving laser eye surgery, however, the MDU pointed out that these claims were primarily due to patients' “unrealistic expectations” of LASIK rather than “faulty surgery” news.bbc.co.uk. A 2003 study reported in the medical journal Ophthalmology found that nearly 18% of treated patients, and 12% of treated eyes, required retreatments ncbi.nlm.nih.gov. The authors concluded that “higher initial corrections, astigmatism, and older age are risk factors for LASIK retreatment.”In 2004, the British National Health Service's National Institute for Clinical Excellence considered a systematic review of four randomised controlled trials nice.org.uk nice.org.uk prior to issuing guidance for the use of LASIK within the NHSnice.org.uk. Regading the procedure's efficacy, NICE reported that "current evidence on LASIK for the treatment of refractive errors suggests that it is effective in selected patients with mild or moderate short-sightedness" but that "evidence is weaker for its effectiveness in severe short-sightedness and long-sightedness". Regarding the procedure's safety, NICE reported that "there are concerns about the procedure's safety in the long term and current evidence does not appear adequate to support its use within the NHS without special arrangements for consent and for audit or research". Leading refractive surgeons in the United Kingdom and United States, including at least one author of a study cited in the report, believe NICE relied on information that is severely dated and weakly researchedprnewswire.co.uk escrs.com.
See also - LASEK (Laser-Assisted Sub-Epithelial Keratectomy) OR PRK (Photorefractive keratectomy)Radial keratotomyWavefront
External links - eye-surgery-india.com - Eye Surgery India!http://www.fda.gov/cdrh/lasik/ http://www.clario.org !Category:LasersCategory:Surger yCategory:Medical? !treatmentsCategory:Ophthalmolo gyde:Augenoperationfr:Lasikja: レーシӠ 3;ク
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Websites
AgingEye Times
AgingEye Times provides free access to the latest medical information on diseases of the aging eye in an attempt to empower people to take control of their vision health, while educating them on the importance and need for further medical advances.
http://www.agingeye.net/
LASIK & Vision Correction Procedures
Peter S. Hersh, M.D. and the Cornea and Laser Eye Institute. Author, clinical trial leading to first FDA approval of excimer laser nearsighted correction.
http://www.vision-institute.com/
RxPinoy
Online directory of doctors and dentists in the Philippines. This site also promotes medical tourism in the Philippines.
http://www.rxpinoy.com/
Lasik Institute
Providing articles for patients and journal abstracts for doctors.
http://www.lasikinstitute.org/
Food and Drug Administration
The Consumer Protection Agency of the U.S. Government which monitors medical devices, foods, drugs, biologics, veterinary medicine, and toxicological research.
http://www.fda.gov
Ask Lasik Doctors
Includes a doctor directory, articles and a bulletin board for patients to ask questions and answers.
http://www.AskLasikDocs.com/
All About Vision
A consumer guide to vision, eye health and vision correction techniques.
http://www.allaboutvision.com
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