Presbyopia is an unavoidable consequence of getting older. The lens inside our eyes thickens and hardens, reducing our ability to read and focus on near objects.

Most people deal with the vision problems of presbyopia by wearing eyeglasses with bifocal or progressive lenses or (if they can see well across the room without glasses) by wearing reading glasses.

But two emerging vision correction surgeries may soon help many older Americans see better up close without glasses -- and across the room, too. One is already available in the U.S. and the other is expected to gain FDA approval in the near future.


PresbyLASIK

LASIK, the most popular eye surgery for the correction of nearsightedness, farsightedness and astigmatism, has been around since the early 1990s.

Over the past few years, an advanced form of LASIK has been developed to correct presbyopia. Called PresbyLASIK, the new surgery uses the same laser used for LASIK, but it's programmed to create a multifocal treatment on the cornea, similar to how a multifocal soft contact lens is made. Though PresbyLASIK is not yet FDA approved for use in the United States, it has been used in Canada for several years and a similar procedure called Presbyopic Multifocal LASIK (PML) has been used in Italy since 2002.


Multifocal IOLs

In IOL surgery, the eye's natural lens (located behind the pupil) is removed and replaced with an artificial lens. The surgery can be performed to replace a lens that has a cataract, or can be done solely for purposes of vision correction when no cataract exists.

The Array Multifocal Lens (Advanced Medical Optics) was the first multifocal intraocular lens (IOL) to receive FDA approval for use in the United States (1997). AMO later redesigned the Array lens to create its new ReZoom Multifocal Lens. The ReZoom lens has a center zone for distance vision, surrounded by four concentric rings of modified lens powers for intermediate and near vision.

Other FDA-approved IOLs for the correction of presbyopia in the United States include the AcrySof ReSTOR (Alcon) and the Crystalens (Bausch & Lomb).


Comparing the two procedures

At the recent annual meeting of the American Academy of Ophthalmology, refractive surgeons W. Bruce Jackson, M.D. and I. Howard Fine, M.D. discussed their preferred surgical procedure for correcting presbyopia.

Dr. Jackson, director general of the University of Ottawa Eye Institute (Ontario, Canada), noted that presbyLASIK has several advantages over IOL surgery:

1. PresbyLASIK is less invasive and avoids the risks of intraocular surgery.
2. The eye's natural lens and remaining focusing ability are preserved.
3. The results can be enhanced or reversed if necessary.

He reported the results of a recent study of bilateral presbyLASIK surgery performed on 28 farsighted patients who also had presbyopia: 88% of the patients attained 20/25 or better distance vision and 20/20 near vision. He noted, however, that about 50% of the patients still used glasses for some vision tasks. And though the study participants were generally pleased with their near vision in bright light, they were less satisfied with their ability to read under dim illumination.

Dr. Fine, on the other hand, believes multifocal IOLs are a better surgical solution for presbyopia than presbyLASIK. He noted that advanced surgical techniques have lowered the risks associated with IOL surgery and that IOL procedures can correct higher amounts of nearsightedness and farsightedness than presbyLASIK.

In addition, Dr. Fine said that age-related changes in the eye's natural lens as a person ages can cause vision problems years after presbyLASIK surgery. With multifocal IOL surgery, the natural lens is removed, so this problem is avoided.


Both procedures continue to evolve

Both Dr. Jackson and Dr. Fine admit that presbyLASIK and multifocal IOL procedures still have potential drawbacks and continue to evolve.

"There is always a risk of visual symptoms and loss of quality of vision, and near vision may be insufficient and change, especially with increasing age," said Dr. Jackson regarding presbyLASIK.

Dr. Fine noted that he is impressed with new "accommodating" IOLs being developed that may enable the eye to regain its ability to change focus for different visual tasks and may perform better than the currently-available IOLs for presbyopia.


SOURCE: "Virtues of cornea- and lens-based methods for presbyopia." Ophthalmology Times. January 1, 2008.