Faster reading speed over time indicates brain adapts to multifocal IOLs

San Francisco-When analyzing multifocal lens performance, it is important to follow patients over time and to remember that there is a brain behind the eyes, said Manfred R. Tetz, MD, of the University of Berlin, Germany.

Dr. Tetz and his colleagues followed 25 patients (50 eyes) for at least 6 months and up to 18 months postoperatively. The patients had one of two multifocal IOLs implanted bilaterally (Tecnis, Abbott Medical Optics, 13 patients; AcrySof ReSTOR, Alcon Laboratories, 12 patients).

Using reading speed as the measure of performance, the researchers found that patients had a marked faster reading speed, 200 words per minute at standardized font sizes and illumination conditions, than was found in previous studies that followed patients for only 3 months.

"This indicates there is a neural adaptation by the patient over time," Dr. Tetz said.

Uncorrected visual acuity at intermediate distance was very good for both groups, at an average of about 20/40, and no statistically significant differences were seen in near or distance acuity. Although reading speed in both groups slowed at decreasing font sizes, the patients in the ReSTOR group maintained a higher reading speed at the smaller font sizes and a slightly faster reading speed over time than did the Tecnis patients.

"This was a surprise," Dr. Tetz said.

Visual disturbances over time were minimal in both groups of patients.

"We asked the patients about many different things, such as distorted near vision, distorted distance vision, blurring, or problems with night vision," Dr. Tetz said. "Most patients did not have any problems with these lenses."

Even the most commonly reported complications (halos and glare) were rare, according to Dr. Tetz.