SAN FRANCISCO, Aug. 30 -- A new excimer laser system employing a flying spot effectively corrects low to moderate nearsightedness and astigmatism, according to a report in the journal of the American Academy of Ophthalmology. Marguerite B. McDonald, lead author and AAO spokesperson, calls the new laser system a flying spot because the small-beam laser, which pulses 55 times per second, is directed by an active corneal tracking device that scans the eye position 4,000 times per second. The laser beam rapidly jumps from one side of the cornea to the other to allow for thermal relaxation of the corneal tissue.
The study details the results of FDA-approved phase III US clinical trials. One year after the procedure, 98.1 percent of patients with myopic eyes but no astigmatism achieved uncorrected visual acuity of 20/40 or better, and 72 percent achieved 20/20 or better. Of patients with low myopia and astigmatism, 97.4 percent achieved 20/40 or better, and 61.7 percent achieved 20/20 or better. Of those patients with moderate myopia and astigmatism, 93.4 percent achieved 20/40 or better, and 61.2 percent achieved 20/20 or better. Researchers say this new technique creates a smoother corneal shape, which is thought to reduce the incidence and degree of complications -- such as halos, haze, and night glare -- experienced by a small percentage of patients who undergo laser vision correction.