Tracking difficulties after femtosecond laser flap creation with the LADARVision excimer laser system.

Purpose: To describe a series of myopic patients in whom a LASIK flap was created with the IntraLase femtosecond laser. The LADARVision (Alcon Laboratories Inc) tracking system failed and resulted in postponement of surgery.
Methods: Five myopic Asian patients with darkly pigmented irides underwent bilateral superior hinge flap creation with three different femtosecond laser (IntraLase Corp) pulse frequencies: 15, 30, and 60 kHz. Mean patient age, preoperative best spectacle-corrected visual acuity (BSCVA), and spherical equivalent refraction were 33 years, 20/20, and -6.25 diopters (D), respectively. Despite uncomplicated flap-lift and adequate pharmacologic dilated pupil diameter >7 mm, difficulty was experienced with LADARVision eye tracking in 9 of 10 eyes. Intraoperative manipulations (fluid application, levitation of the laser bed, and tracking through a repositioned flap) were attempted to facilitate eye tracking at the time of femtosecond laser flap creation, but without success.
Results: The flap was repositioned, and patients were asked to return 1 to 5 days later, at which time the flap was relifted, eye tracking was successfully achieved, and the surgery was completed. Mean postoperative uncorrected visual acuity was 20/18 and no eyes lost any lines of BSCVA at 1 year.
Conclusions: Irregularities of the IntraLASIK stromal bed surface induce forward light scatter, and dark ocular pigmentation further reduces retinal reflectance, leading to tracking failure with the Alcon LADARVision platform. Delaying the surgery by 1 to 5 days may aid in reducing the light scatter, so that eye tracking can be achieved.