Corrective Eye Surgery

2007-04-17 10:41:55

( Pharmeceutical-Medical )



Corrective eye surgery is a relatively new field, which began in the 1960’s. Laser Assisted In Situ Keratomileusis, or LASIK, is a kind of corrective eye surgery that uses excimer lasers to permanently alter your cornea. If you have a refractive error, such as myopia (near-sightedness), hyperopia (far-sightedness) or astigmatism, then you can benefit from LASIK.

In the US, approximately 5 million LASIK procedures have been completed since 1995, with 1.5 million procedures in 2005 alone. Centers offering LASIK treatment include LASIK Plus Vision Center and Lasik Eye Center, among others.

Other options for vision correction surgery include:
• Radial keratotomy (RK)
• Laser vision correction
• Photorefractive keratotomy (PRK)
• Laser thermal keratoplasty
• Intacs
• PRELEX (presbyopic refractive lens exchange)

If you fit the following criteria, then you are a candidate for corrective eye surgery:
• 18 years or older for myopia or hyperopia; 21 years or older for astigmatism
• Stable refraction for at least 1 year
• Myopia between -0.50 and -14.00 diopters
• Astigmatism less than 5.00 diopters
• Hyperopia less than +6.00 diopters
• No eye problems, such as keratoconus, herpes keratitis, diabetic retinopathy or cataract/glaucoma
• No medical problems, such as collagen vascular or autoimmune diseases, AIDS
• Not pregnant or breastfeeding
• Without a pacemaker and not on medications

Preoperatively
Before any surgery is done, you must undergo a complete eye exam. It will measure your refractive error and check stability. A pachymeter will measure your corneal thickness and wavefront analysis will show interaction of light with your optical system. You also have to undergo corneal topography to map your corneal surface.

Intraoperatively
LASIK usually takes 15 minutes per eye. Under the microscope of the laser, your cornea is marked, and then a suction ring is applied. A microkeratome is used to create a flap in your cornea, which is retracted to expose your corneal stroma. The laser is then used for ablation and your cornea is re-sculpted. Finally, the flap is closed.

Postoperatively
Following closure, antibiotic and anti-inflammatory drops are put into your eyes, given 4 times a day for 1 week. Your eyes are then covered by a transparent eye shield. You may experience eye discomfort (itching or burning), which usually goes away. In case of dryness, you may use artificial lubrication. Improvement in eyesight is noticed immediately.

Follow-up visits are scheduled after 1 week, 1 month, 3 months, 6 months, and 1 year. Enhancement surgery for under- or over-correction may be performed once your refractive error is stable.

Complications
Complications of LASIK may occur intra- or post-operatively.

Your microkeratome flap usually causes the intraoperative complications, such as perforation, buttonholes, incomplete, irregular, decentered or free flaps. If these occur, your operation is stopped.

Refractive complications, such as halos and glares, induced astigmatism, and under- or over-corrections may occur post-operatively. You can also experience dislocated flaps and flap folds, interface debris, epithelial ingrowth, corneal abrasions, diffuse lamellar keratitis, or rarely, infectious keratitis.

Advancements
Advancements in refractive eye surgery include custom ablation, the use of a femtosecond laser, and possibly a photoablative inlay in the future.


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