RALEIGH … When it comes to laser vision correction techniques, a little personal knowledge can go a long way. Just like buying shoes or cars or clothes, knowledge can help make you a savvy consumer.

In this article, we explore the high-tech side of ophthalmology to review how the eye sees and develop some personal knowledge about laser vision correction.

How our eyes see
Remember from high school science that the eye does not actually “see” an object … only the light that reflects off the object. Passing through the cornea, reflected light is refracted and coarsely focused for the lens, which provides sharp focus, under normal conditions, to the retina.

The retina is a photosensitive nerve layer that sends visual information to the brain via the optic nerve. For perfect vision, the eyeball must be perfectly round, the cornea must refract perfectly, and the lens must focus perfectly on the retina.

Four problems, three fixes
Imperfections in three areas of the eye are the cause for four of the most common forms of vision impairment:

  • Myopia (nearsightedness) … Close object appear sharp, but distant ones appear blurred. The eyeball is too long or the cornea is too steep.
  • Hyperopia (farsightedness) … Close objects appear blurred, but distant ones appear sharp. The eyeball is too short or the cornea is too flat.
  • Astigmatism (blurred vision) … The cornea is oval-shaped rather than round resulting in multiple focal points for incoming images, which result in multiple images striking the retina.
  • Presbyobia (aging eye) … The eye looses its ability to focus due to aging.

Laser procedures
One of the more common procedures for laser vision correction is LASIK (laser in situ keratomileusis), and one of the latest technologies is LASEK (laser epithelial keratomileusis). Both are pronounced the same and go after the same results, but that’s where the similarities end.

LASIK is a surgical procedure that involves cutting a small flap in the cornea. The process ultimately corrects nearsightedness. LASEK is a newer procedure that does not require cutting on the eye. Instead, LASEK uses an alcohol-based solution to enable sliding the cornea aside. LASEK is especially useful for people with thin corneas.

Another procedure for reshaping the cornea without surgery is PRK (photo refractive keratectomy), which is an outpatient procedure generally performed with local anesthetic eye drops.

PRK gently reshapes the cornea by removing microscopic amounts of tissue from the outer surface with a cool, computer-controlled ultraviolet beam of light. The beam is very precise. PRK takes only a few minutes, and patients are typically back to daily routines in one to three days.

Reality check
Laser vision correction often restores 20/20 vision; thus eliminating a person’s dependency on eyeglasses and contacts. The consumer should be aware there is risk involved. According to the U.S. Food and Drug Administration, the success rate for LASIK surgery is around 95 percent. That means five out of every 100 patients must continue to wear glasses even after the procedure. Up to 15 percent continue to require glasses occasionally, according to the FDA.

Some laser vision correction centers in North Carolina
The Raleigh Eye Care Center www.raleigheyecenter.com/map_&_directions.html
Eye Associates of Wilmington www.wilmingtoneye.com

References
MEDLINE www.nlm.nih.gov/medlineplus/ency/article/007018.htm
NIH/NEI www.nei.nih.gov/
FDA1 www.fda.gov/fdac/features/1998/498_eye.html
FDA2 www.fda.gov/fdac/features/2001/501_eyes.html

Feedback? Send email to ecrockett@nc.rr.com