TAIWAN, July 2007 -- A study published in the Journal of Refractive Surgery has affirmed that patient vision is better when involuntary eye movement is tracked during Lasik. The study indicates that astigmatism correction is significantly improved with eye tracking on, and nearsighted Lasik correction is moderately improved.
Even when staring directly at an object, human eyes continue very small involuntary movement. Newer systems used for Lasik and similar laser eye surgery have the ability to track the eye's movement and adjust application of the laser energy.
Fifty Lasik patients who received surgery at the Buddhist Tzu Chi General Hospital in Hualien, Taiwan to reduce nearsighted vision and astigmatism were included in the study. Astigmatism is when the cornea (clear front of the eye) is elliptical like the back of a spoon. The "tip" of the spoon points in a specific direction, like the hour hand of a clock. Active eye tracking of the excimer laser was on for half of the patients, off for the other half. During surgery, all patients were instructed to hold their gaze directly at a fixation light in the laser.
In the patients treated with the eye-tracker off, all achieved 20/40 uncorrected vision or better and 64% achieved 20/20, however more astigmatism remained when compared with the patients treated with the eye-tracker on. Those treated with the eye-tracker on achieved better visual results.
