Abstract
Abstract: :
Purpose: To evaluate refractive outcome, clinical efficacy and higher order corneal aberrations for myopic PRK with an active eye tracking system (VISX STAR S3 ActiveTrakTM). Methods: A retrospective study of 176 consecutive eyes from 107 patients were treated with the VISX STAR S2TM (n=106 eyes) and VISX STAR S3 ActiveTrakTM (n=70 eyes) excimer laser systems using a 6.0 mm treatment zone. Mean SEs were -4.35 D (-1.38 to -10.00 D) for the STAR S2 group and -4.61 D (-1.25 to -10.13 D) for the STAR S3 group. All patients were treated at 10 Hz and had a 6.4 mm epithelial laser/scrape. Pre-op evaluation, surgical treatment and post-operative care were the same in both groups of eyes except for the active eye tracking in the STAR S3 group. Follow-up was from 1 week to 6 months. Changes in corneal optical aberrations following PRK were compared (pre-op and 3m), using custom software, for a random group of 10 eyes (age and SE matched) from each treatment group. Results: At 1 week, 1 month and 6 months, 31% and 66%, 48% and 78%, and 77% and 92% of patients had an UCVA of 20/20 or better for the STAR S2 and S3 groups, respectively. At 1 week, 1 month and 6 months, 51% and 51%, 63% and 62%, and 72% and 60% of patients had a predictability of +/- 0.25 D for the STAR S2 and S3 groups, respectively. We found that there was a trend to a larger increase in corneal spherical aberration and coma in the STAR S3 group when compared to the STAR S2 group. Conclusion: The clinical data shows that patients treated with myopic PRK with the active eye tracking system had a statistically significant improvement in visual outcomes from 1 week to 3 months, despite demonstrating a trend towards an increase in higher order corneal aberrations.
Keywords: 552 refractive surgery: PRK • 547 refractive surgery: corneal topography