Schallhorn and his co-workers did an analysis of two studies. In one study, doctors performed wavefront-guided Lasik surgery on 100 patients with low to moderate nearsightedness. Twenty-one of them took a night-driving simulator test, which simulated driving at 55 miles per hour on a rural road at night. In the other study, doctors performed conventional Lasik surgery on 498 patients with low to moderate myopia, and 44 of them took the simulator test.
The researchers discovered there was a loss in night-vision capability in 38 percent to 42 percent of patients receiving the conventional Lasik procedure. But only 3 percent of those emerging from wavefront-guided Lasik surgery had a deterioration in their night vision.
On the positive side, conventional surgery produced an improvement in night vision among 6 percent to 13 percent of patients, while wavefront-guided surgery improved the "night eyes" of 18 percent to 46 percent of recipients. It%u2019s been known for some time that, even if Lasik improves patients' visual sharpness, the actual quality of their vision can suffer in some cases. This includes seeing under conditions of low light contrast, such as driving at night or in fog.