Wavefront-guided LASIK improves night driving performance

Patients concerned about night vision quality after LASIK should be aware of a recent study that compared night vision in patients treated with conventional versus wavefront-guided technology. Results of this study were presented by retired Navy Captain Steven C. Schallhorn at the annual meeting of the American Academy of Ophthalmology.

With conventional LASIK, treatment is based on the patient’s eyeglass prescription. After obtaining the prescription via the familiar “Which is better, one or two?” test, the numbers are entered directly into the laser.

With wavefront-guided LASIK, treatment is based on the patient’s wavefront map. The map is produced by scanning the eye with a laser wavefront analyzer. Each map is unique, much like a fingerprint. Because the resultant laser treatment is also unique, wavefront-guided treatments are also known as custom treatments.

The study measured night driving performance in a simulator at the Naval Medical Center in San Diego. Prior to surgery, both the conventional group and the wavefront-guided group underwent baseline tests with the simulator. After surgery, both groups were measured again. The simulator measured how quickly patients could detect and identify potential hazards under both normal and glare conditions.

The main finding of the study was that the average night driving performance was reduced after conventional LASIK, but improved significantly in those who underwent wavefront-guided surgery. Dr. Schallhorn characterized the difference between the two groups as “startling”. The difference was present in both glare and non-glare conditions.

National Highway Traffic and Safety Commission criteria were used to define a significant gain or loss of night driving performance. By defining a significant decrease in reaction time as greater that 0.5 seconds, which at 55 mph represents a distance of more than 44 feet, 38% to 42% of eyes in the conventional group had a significant loss of night driving performance compared to only 3% with wavefront-guided surgery. Conversely, 18% to 46% of wavefront eyes performed better than before surgery versus only 6% to 13% of eyes that improved after conventional surgery.

According to Dr. Schallhorn, "The compelling data from these analyses provided the basis for the decision to authorize wavefront-guided all-laser LASIK in U.S. Navy aviators."