Laser Eye Treatment

Surgeons performed the first laser-based PRK eye surgery procedure in the late 1980s. After extensive clinical trials, ophthalmologists looked with great hope to the cool new excimer laser to provide patients with rapid, predictable results. But, unfortunately, the original operation, called “PRK eye surgery” (photorefractive keratectomy), has failed to live up to many doctors’ early expectations.

PRK Eye Surgery

During the PRK eye surgery procedure, surgeons remove the thin, gel-like outer corneal layer called the epithelium. Laser pulses are aimed at the newly exposed surface of the cornea to vaporize microscopic layers of tissue, thereby changing the curvature of the eye’s transparent outer lens

Although many mildly and moderately nearsighted patients have been helped by PRK, for reasons I’ll cover in a future article, PRK eye surgery patients sometimes hesitate to recommend it to their friends.

Ophthalmologists and eye surgeons refer to focusing errors as “mild,” “moderate,” and “severe,” based on “diopters,” a measurement unit used to quantify the light-bending power of a lens.

Diopters define the exact amount of correction you need. A 1 diopter lens can bring light rays to a focus one meter away from the lens. So if you have a -1 diopter lens prescription (written as -ID), your eye focuses clearly without correction at one meter, or approximately the length of your arm. If you need a-2 diopter lens, which is twice as strong, you can focus light at only half a meter. This means that you can see clearly without glasses about half way down your arm. If you need a-10 diopter lens, your eye focuses light at about two inches from your nose.

We sometimes tell patients to think of diopters in relative terms; the more out of focus the eye, the higher the number used to represent the refractive error.

PRK eye surgery is also dependent on the diopters or strength of your prescription – too strong and you may not be a suitable candidate.