Refractive Surgery Should You Do It?

By Scott Burge, OD

Are you thinking about having refractive surgery, most commonly referred to as LASIK? There are three primary considerations to be aware of in order to make the right decision for yourself.

First, what vision correction type are you? Myopic (nearsighted) patients are the vast majority of refractive surgery cases. The pre-operative spectacle and/or contact lens prescription is a minus number. The LASIK procedure flattens corneal curvature, thereby reducing the minus number to zero when the post-operative outcome is perfect. This is what LASIK was originally designed to do. Years of technological development, experience and thousands of patient procedures have resulted in a very successful surgical option for myopic patients who want out of glasses and contacts.

On the other hand, hyperopic (farsighted) patients are a very small minority of refractive surgery cases. The pre-operative prescription is a plus number. Corneal curvature must be made steeper to reduce the plus number to zero. Later advancements in LASIK technology achieved some success in accomplishing this. While there are impressive success stories, it is less assured for hyperopic patients. All LASIK surgeons do procedures for myopic patients, however, only a minority of surgeons do hyperopic cases. Therefore, it is very important to get a good referral when selecting your LASIK surgeon.

Most vision corrections include some amount of a measurement for astigmatism. Current LASIK technology can treat most cases of myopia with astigmatism and some cases of hyperopia with astigmatism.

The second primary consideration is the amount of pre-operative correction, which needs to be reduced to zero. There are limits in all cases. A general guideline is myopic cases up to -10.00 and hyperopic cases up to +4.00. Highly experienced surgeons have had success with amounts greater than these general limits. However, the higher the amount attempted for treatment, the greater the possibility of post-operative optical distortion and compromise of the cornea. Additionally, corneal thickness is a determining factor for the amount of correction possible. Obtaining two or three opinions about corneal thickness for high limit cases is strongly recommended.

Because LASIK is surgery, the amount of correction to be treated should be worth the risk and cost of the procedure. When uncorrected vision is 20/200 or worse, the benefit of a perfect LASIK outcome is great. For minus measurements, 20/200 equates to an amount of -2.00; 20/400 (“the big E” on the eye chart) equates to -4.00. Myopic patients with amounts -2.00 to -8.00 generally are the most doable and have “the most bang for the buck”. For low minus measurements at -1.00, an alternate refractive surgery procedure, PRK, may be recommended for those patients who want treatment even though pre-operative uncorrected vision is not that bad.

Patient age is the third primary consideration. Younger patients in their 20s and 30s will enjoy many years after LASIK without glasses or contacts until their early to mid 40s when presbyopia results in the need for reading glasses. Nearsighted patients in their 40s or older need to be mindful that having LASIK will eliminate the eye's pre-operative near advantage, necessitating the need for reading glasses after surgery. As is often said, “Talk with your doctor to be sure this is right for you.”