11. THE FUTURE



11-1. What are multifocal corneal ablations?

Multifocal corneal ablations are laser treatments designed to correct both distance and near vision. The laser creates a “bifocal” effect, which allows a person to see well, not only far away, but also up close. The goal of eliminating glasses for distance and near has been an elusive one. Several investigators have tried a variety of methods over the past decade with mixed results. Most of these studies have been done outside the United States, where doctors can more easily try new procedures. Recent attempts to create good distance and near vision with the excimer laser appear to be more promising than ever.

11-2. How does a multifocal ablation achieve good distance and near vision?

The laser sculpts ring-shaped treatment zones around the optical center of the cornea. The “central zone” is “steepened” in order to focus the eye for near vision. The zone just outside the central zone, the “peripheral zone” is targeted for distance vision. This pattern of laser treatment has been patented by VISX, Inc., of Santa Clara, CA.

11-3. Does multifocal ablation work for nearsightedness, farsightedness, and astigmatism?

Multifocal ablations appear to work well for all types of correction. Of course, the procedure should only be performed in people who need a different glasses or contact lens prescription for distance and near. This means, that most candidates for multifocal ablations are older than 42 years of age. At the present time, multifocal ablations seem to work best for farsighted (hyperopic) people. This may be because farsighted people have more difficulty with near vision than nearsighted people. Consequently, farsighted people are grateful for any improvement in near vision, even if near vision is not perfect. Nearsighted people are harder to please. They often require very precise correction of near vision.

11-4. How good are the results of multifocal ablation?

Multifocal ablation is a relatively new technique, and only a small number of patients have had this procedure. All patients achieved distance vision of 20/40 or better, and most were better than 20/25. Reading vision was J3 or better in all patients. This means they could usually read the newspaper without reading glasses. Still, some patients found reading glasses reduced eyestrain, or allowed them to read extremely small print. All patients who had the VISX procedure seem very satisfied with the results.

11-5. Are there any complications of multifocal ablations?

The usual complications of LASIK should be kept in mind, such as overcorrection, undercorrection, poor corneal flaps, infection, and so forth. These complications are rare, and there do not seem to be any unexpected complications of multifocal ablations with the VISX technique. Some earlier techniques produced “ghosting” of images, and poor distance or near vision. As more multifocal ablations are performed, it will become clearer if complications are a problem.

11-6. Does wavefront improve the results of multifocal ablations?

It appears that wavefront ablations do improve the results of multifocal ablation. This may be because wavefront techniques take into account optical aberrations of the entire eye, not just the cornea.

11-7. When will multifocal ablations be available in the U.S.?

Clinical trials have already begun in the U.S. Generally, it takes a few years before a new technique, like multifocal ablation, becomes available to the general public.

11-8. What is capsular refilling?

Capsular refilling, also known as “phaco-ersatz (artificial lens)” is a technique in which the material within the crystalline lens of the eye is removed and replaced with a clear synthetic material that can focus an image on the retina.

11-9. Who is a candidate for capsular refilling?

Two kinds of people are candidates for capsular refilling: Those who have poor vision caused by cataracts, and those who have poor vision caused by being nearsighted or farsighted.

11-10. How does capsular refilling work?

A small incision is made into the wall of the eye, and an even smaller incision is made in the crystalline lens. The lens is covered with a capsule, just like a grape is covered by a thin skin. The tip of an instrument, known as a phacoemulsifier, is inserted through the capsule. The lens material is “liquefied” and sucked out. The synthetic material is injected into the “capsular bag,” and the capsular opening is “sealed” with a “plug.” 

11-11. What type of material is used to replace lens material in capsular refilling?

A variety of materials have been used experimentally, including hydrogels (liquefied soft contact lens material). It is not certain that the ideal material has been found yet. The material must have an adjustable “refractive” power, so any eye can be treated. The chemical substance must also be nontoxic and biocompatible.

11-12. What is the advantage of capsular refilling?

Advocates of capsular refilling point out that the operation preserves the adjustable nature of the crystalline lens. They believe this will allow people over age 42 to see both at distance and near without glasses. Because the accommodative reflex of the lens is maintained, it should theoretically be possible for people who have this operation to function well without glasses.

11-13. Is capsular refilling safe, or are there some complications?

The surgery for capsular refilling is technically very challenging. Yet, some surgeons are quite skilled at performing the procedure. Most capsular refilling surgery has been performed on animals. Very few cases have been performed on humans. It will probably be a very long time before this operation is widely available. And, there are many uncertainties about capsular refilling, such as the ideal material to fill the bag, and how well accommodation (the ability for the eye to adjust from distance vision to near vision) will be preserved.



Acknowledgement

I wish to thank Marcia Straile for her proficient typing and editing, Ann Marsh for her straightforward illustrations, and Daniel Friedlaender for his skillful technical support.

M.H.F.