Comparison of eye-tracking success in laser in situ keratomileusis after flap creation with 2 femtosecond laser models

Abstract

Purpose: To determine the efficiency of an eye tracker after laser in situ keratomileusis (LASIK) flap creation with 1 of 2 femtosecond laser models. Setting: Tertiary referral center, Singapore National Eye Center, Singapore. Design: Randomized clinical trial. Methods: The LASIK flap was created with an IntraLase (Group A) or a VisuMax (Group B) femtosecond laser. An Advanced Control Eye Tracker was initiated 3 times to obtain iris recognition. Eye tracking was considered successful if the eye movements could be followed despite the presence or absence of an opaque bubble layer (OBL). Univariate-multivariate logistic regression analysis was performed. Results: Preoperatively, the mean values (ranges) of the 87 eyes were sphere, -5.64 diopters (D) ± 2.17 (SD) (-9.75 to -0.25 D); cylinder 1.65 ± 1.63 D (-3.75 to 0.00 D); optical zone, 6.34 ± 0.20 mm (5.6 to 7.0 mm); keratometry, 43.48 ± 1.32 D (40.1 to 42.8 D); flap thickness, 109.30 + 5.21 μm (90 to 115 μm). Eye tracking was successful in 38 (90.5%) of 42 eyes in Group A and 43 (95.6%) of 45 eyes in Group B. No specific type of OBL was seen in either group. The LASIK was completed in all eyes. There was a statistically significant association between positive tracking and a smaller optical zone (P=.03). There were no statistically significant differences in eye tracking between the 2 femtosecond lasers. Conclusions: Eye tracking was achieved in more than 90% of cases after LASIK flap creation with 1 of 2 femtosecond laser models, even in the presence of an OBL. © 2011 ASCRS and ESCRS.