Study: Wavefront-optimized excimer laser ablation not culprit in night vision disturbances

San Francisco-Wavefront-optimized excimer laser ablation does not appear to induce night vision disturbances-in fact, patients were more likely to report fewer night vision disturbances after the procedure than they did preoperatively, according to Olivia Lee, MD, Emory University, Atlanta.

She and her colleagues performed a retrospective chart review on 346 consecutive eyes in 176 patients who underwent PRK using a proprietary excimer laser (Allegretto Wave, Alcon Laboratories) or LASIK. Thirty percent of the eyes underwent PRK, and 70% underwent LASIK. All procedures were performed by the same surgeon from January 2005 to December 2006.

Patients completed questionnaires both preoperatively and at 3 months postoperatively to assess the incidence of halos and difficulties they encountered driving at night.

At 3 months postoperatively, no eyes experienced severe worsening of halos, 3.5% of eyes experienced moderate worsening of halos, and 6.5% experienced mild worsening of halos.

"Eight percent of patients actually noted some type of improvement," Dr. Lee said.

When analyzing night-driving symptoms, only 2.3% of eyes experienced moderate symptoms, and no eyes experienced severe symptoms postoperatively.

When examining the changes in night-driving disturbances pre- and postoperatively, no eyes experienced severe worsening of symptoms, and 1.2% of eyes experienced moderate worsening. Approximately 75% of eyes experienced no change, and approximately 14% of eyes noted some improvement.

"Overall, there was no difference or correlation in pupil diameter or pre- or postoperative manifest refraction spherical equivalent and changes in halos or difficulty with night driving," Dr. Lee said.

"Night vision complaints rarely occur after wavefront-optimized laser ablation," she concluded. "In our study, patients were more likely to experience no change or have a diminution of symptoms than to have a worsening. Finally, no preoperative factor was correlated with difficulty in night driving."