Aspheric lens demonstrates night-driving and contrast sensitivity benefits

Results of a prospective, randomized, observer- and subject-masked, contralateral eye study demonstrate benefits of an aspheric IOL (AcrySof IQ model SN60WF, Alcon Laboratories) compared with a spherical single-piece IOL (AcrySof model SA60AT, Alcon Laboratories) for providing better contrast sensitivity and driving performance, said Robert P. Lehmann, MD, a private practitioner in Nacogdoches, TX.

The study enrolled 75 patients who were implanted with the aspheric IOL in one eye and the spheric IOL in the fellow eye. A subset of 45 patients underwent contrast sensitivity testing with and without glare using the Functional Acuity Contrast Test viewed through a contrast sensitivity measuring instrument (Optec 6500 Viewer, Stereo Optical). Forty-four of those patients participated in evaluation of night-driving performance using a portable night-driving simulator. All of the testing was performed at a minimum of 3 months after the second eye implantation.

Contrast sensitivity assessment revealed statistically significant differences in favor of the aspheric IOL under mesopic conditions without glare at 3 and 6 cpd. The night-driving tests evaluated detection and identification distances for road warning signs, text signs, and a pedestrian in city and rural scenarios under normal conditions and with glare or fog. The driving performance results consistently demonstrated better performance in eyes with the aspheric IOL and the differences favoring the aspheric IOL eye achieved statistical significance in multiple comparisons. In many of the test situations, the improved stopping times with the aspheric IOL exceeded 0.5 seconds, which is a threshold considered relevant for driving safety.

"These data demonstrate fairly conclusively that the aspheric design of the AcrySof IQ IOL merits not only theoretical but also functional real-world benefits," Dr. Lehmann concluded.