SEP 08, 2009
Investigators used customized software that objectively evaluates ablation centration to confirm that automated infrared eye-tracking during LASIK improves refractive outcomes and predictability.
They compared two cohorts of patients who underwent conventional myopic LASIK using the Bausch & Lomb Technolas 217A laser platform. One group of 37 eyes underwent LASIK with manual eye-tracking, while a second group of 37 matched eyes underwent automatic infrared pupil-tracking. All patients had a similar preoperative manifest spherical equivalent and underwent a uniform surgical procedure.
Using Bausch & Lomb's Orbscan II, they obtained slit-scanning videokeratography preoperatively and six months postoperatively for all eyes. The data was processed with the Ohio State University Corneal Topography Tool (OSUCTT) to generate the topographic functional optical zone (TFOZ). The software first located the lowest power 3-mm zone on the topographic refractive power map corresponding to the surgically flattened region. It then used an algorithm to expand this area into the total treated area based on the refractive map and located the center of this larger area, which was defined as the TFOZ center. By comparing the TFOZ center with the pupil center, the amount of decentration was quantified using vector analysis.
Postoperative UCVA was significantly better in the infrared-tracked group compared with the manually-tracked group. Although there was no statistical difference in mean centration between the groups, four eyes (10.8 percent) in the manually-tracked group were topographically decentered 1.0 mm or more, whereas none in the infrared-tracked group were decentered to this extent.
The authors suggest that their use of customized software to evaluate centration objectively confirms that automated infrared eye-tracking during excimer laser ablation improves refractive outcomes and the predictability of treatment results.
Dr. Pandit receives lecture fees from Vistakon Johnson & Johnson Vision Care, Inc.