Monday, December 6, 2010

Can Boomers Throw Away Their Reading Glasses?

By John Gever, Senior Editor, MedPage Today
Published: October 25, 2010
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

CHICAGO -- With the baby-boom generation now firmly in the age range when near-range vision goes blurry, advances in refractive surgery and implants could allow many of them to do away with reading glasses, researchers said here.

A series of presentations at the American Academy of Ophthalmology's annual meeting indicated that new types of intracorneal implants and LASIK-like procedures show promise for eliminating presbyopia, the progressive deterioration of near vision that afflicts virtually everyone older than 45.

Among the innovations highlighted at the meeting: a doughnut-shaped corrective lens inserted under the cornea; a thin disk that restricts the pupillary opening, improving depth of focus in the same way as a pinhole camera; and a noninvasive, implant-free laser procedure that cuts concentric rings in the corneal stroma to alter its refractive power.
None of these are yet approved by the FDA.

At a press briefing, Gustavo Tamayo, MD, of the Bogota Laser Refractive Institute in Bogota, Colombia, described in broad strokes the procedures that are available in South America and Europe, which can target the cornea, the sclera, the anterior chamber, or the lens itself.

Many procedures are owned and developed by U.S. companies, though, and eventual FDA approval is expected. Several of these were the focus of scientific presentations at the AAO meeting, including a report from one U.S. clinical trial.

Intracorneal lens

Ioannis Pallikaris, MD, of the University of Crete in Greece, discussed a recent one-year clinical study with an intracorneal bifocal lens called Flexivue.

The implant has a hole in the center, not as part of its refractive design but to aid in centering it over the pupil.

Session discussant Karl Stonecipher, MD, of TLC Laser Eye Center in Greensboro, N.C., noted that "centration" is a major issue for all types of refractive alteration intended to assist the natural lens -- vision will be imperfect and sometimes worse than before if the corrective intervention is even slightly out of alignment with the lens.

Pallikaris said the lens is 20 microns thick and 3 mm in diameter and is inserted into a pocket created within the stroma with a femtosecond laser.

He reported data on 15 patients with a mean age of 51 receiving the implant -- one per patient in the nondominant eye.

Mean baseline near-vision acuity was 20/50. Within one week of the implant, it improved to 20/32, settling at 20/25 by the third month where it remained for the full year of follow-up in the study.

The bifocal lens also provides a focal point for distance vision, to compensate for the impairment of distance vision that otherwise would result from an anti-presbyopic change in corneal refraction.

In the implanted eye, mean uncorrected distance-vision acuity dropped from 20/20 at baseline to 20/40 during the first month, and then recovered to 20/30 at six months.

Pallikaris noted, though, that uncorrected binocular distance vision remained perfect throughout the entire study, because the artificial lens is placed only in the nondominant eye.

He reported that all of the patients reported their uncorrected near vision after the procedure was excellent or good, and 92% had stopped all use of reading glasses.

Light-restricting disk

Another approach alters the eye's optics not with a lens but with a small disk that reduces the effective pupillary diameter to create a pinhole effect.

Daniel Durrie, MD, of the University of Kansas Medical Center and DurrieVision in Overland Park, Kan., explained that the concept is similar to the F-stop setting of a camera that opens and closes the lens aperture.

A small aperture setting increases the so-called depth of field, such that objects both near and far are in focus. Consequently, this product does not impair distance vision and could actually improve it.

He is leading U.S. testing of the implant, called AcuFocus, which in its current version (the third to date) cuts the effective pupillary diameter from about 4 mm under indoor artificial light to 1.6 mm. The reduction in light transmission is 95%.

As with the Flexivue lens, it's implanted in only one eye. Durrie told MedPage Today that patients do notice that the reduction in light transmission, but it doesn't diminish their overall binocular vision.

The disk also contains 8,400 tiny holes, 5 to 11 microns each, to allow ocular fluids to pass back and forth across the implant to anterior tissues.

Durrie said the implant can be placed under a corneal flap or in a pocket. He said he prefers a flap because it eases positioning and removal, if necessary.

He reported three-year follow-up data from 163 patients receiving two earlier versions of the implant, which were somewhat thicker, with a larger aperture (restricting light by 89% and 93%) and fewer, larger holes for fluid porosity.

Unlike the Flexivue lens and other approaches that change the cornea's refractive properties, the Acufocus lens had almost no impact on the distance acuity, Durrie said.

Among 44 patients receiving the product's first version, the average uncorrected near-vision grade was J2 and mean uncorrected distance vision was 20/25.

The second version, which had a smaller aperture than the first, produced mean uncorrected distance vision of 20/20 and an uncorrected near-vision grade of J1 in 119 patients.

Durrie said a U.S. clinical trial with the third version is now under way in 504 patients. The product is already marketed in Europe and Asia, he said.

He indicated that the disk, at least currently, is not color-matched to the patient's iris and therefore is visible in some patients, especially those with blue eyes. He indicated that one patient didn't like the cosmetic effect and demanded the implant's removal.

Laser-etched rings

A third approach is somewhat similar to laser keratotomy, except that it uses a femtosecond laser to make concentric circular cuts in the stroma.

Mike Holzer, MD, of the University of Heidelberg in Germany, said that procedure takes just 20 seconds once everything is set up.

The arrangement of the rings and the stromal depth can be adjusted to achieve the desired refractive correction, he said.

He also noted that it does not involve any incisions in eye's surface, virtually eliminating infection risk.

He described results in 25 patients with a mean age of 56 treated in mid-2008, with up to 24 months of follow-up available.

At baseline, the patients had uncorrected near vision of 0.70 logMAR units (SD 0.16), equivalent to about 20/100.

Three months after treatment, their mean near-vision acuity had improved to 0.20 logMAR units, or about 20/30, Holzer said.

At 12 months, the mean value worsened slightly to 0.30 logMAR, but among patients evaluable at 18 and 24 months, it was back to 0.20.

Most patients evaluated at 24 months had gained five to six lines of uncorrected near acuity on a standard chart relative to baseline, Holzer said, allowing them to read newspapers held at a normal distance without reading glasses.

He noted that the procedure does induce a degree of myopia for distance vision. "The ideal patient should be a little bit hyperopic [at baseline]," he said.

However, there was no diminution of middle-distance acuity, he added.

At the press briefing, Richard Lindstrom, MD, of Minnesota Eye Consultants in Bloomington, Minn., discussed still other approaches involving the lens -- either replacing it entirely with a multifocal synthetic lens as part of cataract surgery, or implanting a so-called phakic intraocular lens that rests on top of the natural lens.

These also are largely development-stage products in the U.S., though they are marketed elsewhere in the world.

Lindstrom said a major consideration for all these treatments is the limited reimbursement available from third-party payers.

He noted that Medicare has ruled out payment for surgeries and implants for acuity problems that could be corrected with glasses, and private insurers have largely followed suit.

Consequently, at least for the near future, baby boomers facing combination problems such as cataracts, myopia, and presbyopia will have to pay for these do-it-all procedures out of pocket.

Lindstrom said such patients therefore have a decision to make, regarding how much they're willing to pay for uncorrected perfect vision versus settling for cheaper procedures that correct some problems but still leave them needing glasses or contact lenses for driving or reading restaurant menus.

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