TAIWAN, July 30, 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
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.