Lasik

Laser Vision Correction
By Michael J. Dodd, M.D.

Laser Vision Correction is the best method available today for surgical correction of refractive errors. In this brief article I will attempt to explain to you what can be done to rid you of glasses or contact lenses.

First, some definitions are in order. What do we mean by the term “refractive errors?” This term refers to imbalances in the light-bending properties of the eye which cause blurry vision. Refractive errors can be corrected by glasses, contact lenses and surgery.

There are 4 broad categories of refractive errors: 1) myopia or nearsightedness, 2) hyperopia or farsightedness, 3) astigmatism and 4) presbyopia. Myopic patients cannot see distant objects well without correction. Patients in this category are usually the best candidates for laser vision correction. Hyperopic patients have problems with near and sometimes at distance if their hyperopia is extreme. Many of these patients can be corrected well with lasers except the extreme ones. Patients with astigmatism have problems with near and distance and many of these can be treated with laser vision correction. Presbyopia, or difficulty focusing near age 45, cannot yet be corrected by lasers, but that may change in the future.

What do we mean by the term “laser vision correction?” The excimer laser is the instrument that is used to correct refractive errors. It’s use in ophthalmology was discovered in the early 1980s and it took about 15 years to bring it to clinical use. It acts by projecting onto the front surface of the eye (the cornea) an ultraviolet light (192nm) which ablates (vaporizes) the outer layers causing flattening for myopia and steepening in hyperopia.

There are 2 modes of laser vision correction with the excimer laser. The first is called PRK (Photo Refractive Keratectomy). This was approved by the FDA in October, 1995. The laser light waves create a central cornea abrasion and then flatten the underlying corneal stroma. Because of the corneal abrasion, there is considerable discomfort for about 3 days. The long term results of this treatment are excellent with 95% of patients gaining 20/40 vision or better.

The second mode of excimer laser is called LASIK. This is an acronym for the cumbersome term Laser Assisted In Situ Keratomeilusis. That is why we call it LASIK. This uses the same laser as PRK. But first the front surface of the corneal dome is shaved and a flap created. This flap is turned back (it’s attached by a tiny hinge of tissue) and the laser light is directed to the stroma without creating a cornea abrasion. Once the laser is completed the flap is put back in position. It heals in place very quickly and the patients are more comfortable than with PRK. Again, the visual results are excellent following LASIK. Besides being more comfortable quicker, LASIK patients recover vision faster and LASIK can correct higher degress of myopia, hyperopia and astigmatism.

After LASIK surgery, most patients can return the normal activities in 3 to 5 days. Many can drive the day following surgery.

As with any surgery, there are certain risks associated with laser vision correction. Prior to surgery, there is a detailed written consent which must be read and understood by all patients considering this operation. A complete ophthalmic examination is also required to be certain there are no contraindications to surgery.

Below is listed a graph outlining the range of refractive errors that can be corrected by LASIK.

Myopia -1.00 to -12.00
Hyperopia +1.00 to +5.00
Astigmatism +/-1.00 to +/-5.00

If your prescription falls within these parameters, you may be a candidate.

I hope this brief article has helped you understand the potential of laser vision correction and aided you in deciding if you are a candidate.

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