Cornea Keratorefactive Surgery
Thoughtful keratorefractive surgeons and vision scientists understand that problems continue to exist with keratorefractive surgery that are independent of refractive predictability. An impressive body of literature exists on which to base this belief. One can easily lose sight of this literature in the groundswell of enthusiasm for refractive surgery, which has been caused by recent improvements in short-term refractive accuracy. We cannot afford to be unaware. The issues involved have too great an implication for the public health.
We need to think in detail about corneal optics after refractive surgery because the normal cornea is relatively trouble-free. The cornea after refractive surgery is not trouble-free. It frequenlty has a more aberrated optical performance than its preoperative counterpart. It is often unstable during diurnal cycles and in time periods measured in months and years. Its optical performance can even change instantaneously with changes in pupil size. It can impair peripheral vision more than central vision. Most seriously, it can impair night vision more than day vision by a pernicious combination of factors, and it is irreversible. Once done, there is no return to the preoperative state. Contact lens and spetacles do not permanently alter the physiologic optics of the eye. Refractive sugery does.
When one alters irreversibly the most trouble-free component of the human visual system, one runs the risk of compounding the visual aberration caused by components of the visual system that characteristically show dysfunction with age (the lens and macula.) The young to middle-aged population now seeking refractive surgery will in 30 to 40 years be part of the swelling population over age 55. This population is predicted to increase by 82% between 1980 and 2030. How many keratorefractive patients who can compensate for their aberrated cornea will be able to do so when the lens and macula develop age related changes? How much sooner will they require cataract surgery or visual aids for macular degeneration? These questions have important public health implications.
Consumer groups are concerned about these issues. They note that most patients who undergo refractive procedures are responding to advertising. In 1988 Consumer Reports magazine reviewed the data on radial keratomy and advised its readers against the procedure. They reconfirmed that judgment in their 1992 health letter.
Many reasonable refractive surgeons will listen politely to the various types of arguments, but they will say the arguments are moot now that refractive practice is so successful. Emmetropia is achieved in ever increasing numbers of patients. Patients are happy. The number of refractive procedures increases as even the staunchest critics of refractive surgery are forced to acknowledge its success or find their practice at a competitive disadvantage. These statements are made almost weekly in the trade journals. In short, why worry about refractive surgery as a potential public health hazard when everyone is happy and basking in success? To answer that question, one needs to understand the following ideas.
