Presby LASIK (Multifocal LASIK, Bifocal LASIK, or LASIK for Presbyopia)

Presby LASIK, also known as multifocal LASIK, is an experimental type of laser vision correction surgery that changes the shape of the eye's clear surface (cornea) to establish different zones for seeing at near to far distances.

This surgery corrects presbyopia, which causes near vision to blur as the eye's natural lens begins to stiffen, usually at around age 40. If you are nearsighted and have presbyopia, you may be able to see up close without your usual eyeglasses or contact lenses but not when you are wearing them.

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If you live in the United States, at this time presby LASIK is available only if you are enrolled in a formal study investigating safety and effectiveness of the procedure. Results of these types of studies are used to determine whether the procedure should receive U.S. Food and Drug Administration approval, at which time presby LASIK could become widely available.

At the November 2006 American Academy of Ophthalmology (AAO) meeting in Las Vegas, several eye surgeons presented initial results of small studies indicating outcomes were positive for the procedure, particularly for individuals who are farsighted and who have developed presbyopia because they are older.

Presby LASIK also is called multifocal LASIK because it works on principles virtually identical to artificial multifocal lenses used to provide vision correction for presbyopes. With presby LASIK, laser energy reshapes your eye's clear surface into different zones, such that light is bent or refracted differently in each zone. In this way, both near and distance vision can be achieved simultaneously.

Because presby LASIK still is in investigational phases, different approaches are being studied to determine how the eye should be shaped to achieve the best possible vision correction for presbyopes.

In one presby LASIK method discussed at the 2006 AAO meeting, W. Bruce Jackson, MD, said the cornea's center is altered to enhance near vision while the outer periphery provides zones for distance vision. This configuration currently appears to be the preferred method for providing multifocal LASIK vision correction for individuals who are presbyopic, or farsighted and presbyopic.

For people who are nearsighted and presbyopic, different configurations of eye shapes are being studied. In some cases, near vision correction is provided in the central zone of the cornea, and in others, near vision correction is established in the peripheral area.

Another method of presby LASIK adds what is known as aspheric corrections to the eye's surface. Aspheric shapes are not perfectly round and are thought to help reduce vision distortions or aberrations that generally can be associated with vision correction.

Still other presby LASIK methods under investigation aim to provide customized procedures uniquely suited to the individual's needs and lifestyle. If a person performs considerable close-up work, for example, the presby LASIK vision correction procedure might be adapted to enhance near vision in lieu of better distance vision.
 

A 2006 AAO conference report presented by Jorge L. Alio, MD, PhD, noted that the presby LASIK procedure appears most effective for farsighted people and has demonstrated ability to restore up to moderate amounts of near vision.

Canadian Multicenter Presby LASIK Clinical Trial Results   (reported at November 2006 American Academy of Ophthalmology meeting by W. Bruce Jackson, MD)   This study involved 82 eyes of 49 farsighted and presbyopic patients; the mean age was 56. Results after 12 months (statistics apply to use of both eyes, or binocular vision): Notes: J3 represents the ability to read newspaper print; J1 indicates even finer print. One re-treatment was required in the study group. Half of patients still require eyeglasses some of the time for certain types of activities such as reading or computer work. Contrast sensitivity was reduced immediately after the procedure, but returned to normal levels for this age group.

Alio said presby LASIK works best when patients are very carefully screened to make sure the procedure is right for them. You might be eliminated as a candidate, for instance, if you have undergone previous eye surgery or you have a disease affecting your ability to heal, such as diabetes.

In one Canadian study reported at the 2006 AAO conference by Jackson, 49 farsighted and presbyopic patients were involved, and 82 eyes were treated. In all cases after a year, patients were able to see at 20/25 or better and at J3 (ability to read newsprint) near vision or better.

Because different modifications continually are being tested related to this experimental procedure, it's difficult to interpret results uniformly because they can differ depending on the type of approach used for presby LASIK.

Some researchers report that some presbyopic individuals are able to read without eyeglasses or contact lenses within 10 minutes of a presby LASIK procedure.

If your vision was normal except for presbyopia prior to a procedure, however, you might notice a tendency toward blurred distance vision immediately following presby LASIK. This problem may not necessarily go away, either. As sometimes occurs with vision correction using multifocal artificial lenses, you may increase your risk of developing reduced contrast sensitivity and/or a tendency to see halos around lights at night.

If you lose contrast sensitivity, you may notice decreased ability to distinguish objects against backgrounds of similar colors. But some research indicates that any loss of contrast sensitivity associated with presby LASIK may be only temporary. Ophthalmology Clinics of North America (March 2006) reported studies showing that contrast sensitivity is recovered within about two months of a presby LASIK procedure in people who are nearsighted and within about six months in people who are farsighted.

At the 2006 AAO conference, Michael Assouline, MD, PhD, said in a scientific paper that presby LASIK vision correction for intermediate vision may need to be sacrificed somewhat to make sure contrast sensitivity is maintained following a procedure.

Study results generally show that presby LASIK, like many other vision correction procedures, is unlikely to provide a permanent solution to vision problems related to presbyopia. As the eye changes, future surgical enhancements may be needed. Also, complications associated with the procedure can include loss of ability to see as well as you once did without glasses or contact lenses.