November 2009

 

CATARACT/ IOL

 

Understanding the nuances


by Matt Young EyeWorld Contributing Editor

   
Research suggests that the AcrySof IQ ReStor +3.0 D IOL yields a superior range of intermediate vision Source: Kerry D. Solomon, M.D.

If you want to understand how the AcrySof IQ ReSTOR +3.0 D IOL (Alcon, Fort Worth, Texas) enhances a patient’s range of vision, listen to what “Robert,” from Charleston, S.C., has to say. Interviewed by Kerry D. Solomon, M.D., Arturo and Holly Melosi Professor of Ophthalmology, Medical University of South Carolina, Charleston, S.C.,about vision after implantation of the lens for a promotional video for Alcon, Robert was enthusiastic about the lens.

Here’s a compelling portion of that interview: Robert: I have quite a range [of vision] that I feel I can read without any kind of discomfort or strain.

Dr. Solomon: How’s the distance for computer [work]? Robert: Basically, I do it the same way and never have had a problem with it. [I’m] probably 18 to 24 inches away and [have] no problem with it. Dr. Solomon: Do you mind if we do a little reading? Put that [magazine] at your most comfortable distance where you like to hold things to read. Can you read it? Robert: I sure can. ‘Belatedly, but thankfully, governments recognized that the only way to get credit flowing in was …’ [Dr. Solomon interrupts him.] Dr. Solomon: That’s awesome. Move it closer until it goes out of focus. Robert: [He does, and the magazine is nearly at his nose].

Dr. Solomon: Move it back to where it’s a comfortable spot for you. [Robert does so.] Pretty good? Robert: Pretty good. [Dr. Solomon then takes the magazine and slowly and steadily moves it away from Robert.] Dr. Solomon: Still see it? Robert: Still see it. Dr. Solomon: Still see it? Robert: Still see it.

Dr. Solomon: Still see it? Robert: Still see it. [Then the magazine goes out of focus, but by this time it is well over an arm’s length away.] Dr. Solomon: Your range is pretty good. It goes from about here to about here [holding the magazine closer and farther from Robert’s eyes]. Your happy spot is somewhere …

Robert: Right in there [at a very comfortable reading distance].

An expanded range of vision

Dr. Solomon has presented research indicating just how good the range of vision is with the +3.0 D IOL, as compared to the AcrySof IQ ReSTOR +4.0 D IOL (Alcon). The study was a prospective, randomized, multicenter study involving 279 participants, pitting the +3.0 D IOL against the +4.0 D IOL. Participants underwent defocus testing, in which a systematic application of different spherical powers is used to defocus a patient. “This assesses vision and determines at which distance patients on average realize their best vision,” Dr. Solomon said. Under photopic lighting conditions, patient refractions were performed using a phoropter or trial frames and a 100% contrast ETDRS chart at 4 meters. This gave a baseline manifest refraction. Then –5.00 D spherical correction was added and a logMAR figure was recorded. Lens power was decreased in 0.50 D increments with logMAR acuity recorded at each change in correction. Additionally, a +2.00 D spherical correction was added and logMAR also was recorded. Power was then decreased in 0.5 D increments and the logMAR was recorded at each change in correction. Commenting on the study, William B. Trattler, M.D., director, Cornea, Center for Excellence in Eye Care, Miami, said that the –5.00 D of spherical correction added and the +2.00 D of spherical correction added is to “blur everything out.” At other 0.5 D increments in between, “distance vision is working in one area and near vision is working in another area,” Dr. Trattler said. This separates these two components of patient vision, he said, as well as shows where intermediate vision is optimal. With both the +3.0 D and +4.0 D IOL defocus curves begin similarly at +2.0 D on the left hand side of the chart. In fact, distance vision is identical at 0.0 D, and the curves are still similar up until about the –1.0 D point. From there, the +3.0 D IOL line begins to curve upward again, and by –2.0 D (equivalent to 50 cm or—as Dr. Solomon put it—the distance of normal computer vision), +3.0 D eyes are seeing 20/20 while +4.0 D eyes are seeing somewhere between 20/32 and 20/40. The +3.0 D IOL also appears to expand good intermediate range of vision, with +3.0 D eyes seeing near 20/25 at 60 cm and 20/20 at 40 cm, while +4.0 D eyes see closer to 20/40 and 20/25, respectively, at those same distances. The +4.0 D IOL does offer some improvements in vision at the near end of the spectrum, with vision closer to 20/20 at 33 cm than the +3.0 D IOL. However, the +3.0 D IOL optimized functional vision. “As expected, the +3.0 D add power moved the optimal distance for reading out about 7 inches to approximately 16 to 20 inches away from the patient’s face,” Dr. Solomon said. Also of note, according to Dr. Solomon, patients were able to move items within a range at near while maintaining 20/20 (J1) vision (from 16 to 20 inches).

“The ReSTOR +3.0 is definitely more of an intermediate add lens,” Dr. Trattler said. “It helps to avoid a big drop in visual acuity in the intermediate range. For people who are computer users, the +3.0 is a much better lens. But up close, the +3.0 lens doesn’t really give as good vision as the +4.0 lens does.”

Editors’ note: Dr. Solomon has financial interests with Alcon (Fort Worth, Texas). Dr. Trattler has no financial interests related to his comments.

Contact information

Solomon: 843-792-8854, solomonk@musc.edu
Trattler: 305-598-2020, wtrattler@gmail.com

Understanding the nuances Understanding the nuances
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