Abstract
Purpose: :
To investigate the accuracy of the 60 kHz IntraLase femtosecond (FS) laser in creating predictable flaps by comparing attempted flap thickness with postoperative Visante Anterior Segment OCT and intraoperative ultrasound pachymetry flap thickness measurements as well as evaluating these two methods for determining flap thickness.
Methods: :
This study is a retrospective review of 81 patients (151 eyes) who underwent IntraLase-assisted LASIK and received both intraoperative ultrasound pachymetry and postoperative Visante OCT measurements. Flap thickness was measured intraoperatively using the subtraction method for pachymetry and was measured postoperatively by two masked, independent observers using Visante OCT software.
Results: :
Femtosecond lasik flaps averaged within 4 microns of attempted flap thickness by both ultrasound intraoperative pachymetry and postoperative Visante OCT. There was no statistically significant difference between attempted and intraoperative pachymetry flap thickness measurements, between attempted and postoperative OCT measurements, nor between intraoperative pachymetry and postoperative OCT measurements (p<0.05). Intraoperative pachymetry averaged 4 microns thicker than attempted, while the OCT measurements consistently measured the flaps to average 4 microns thinner than attempted. All OCT measurements were more highly correlated with the attempted flap thickness than were the intraoperative ultrasound pachymetry readings with standard deviation of flap thickness as measured by OCT of only +/- 7 microns.
Conclusions: :
60kHz Intralase lasik flaps are very precise in delivering attempted flap thickness. Visante OCT provides an excellent alternative to intraoperative ultrasound pachymetry, as there is no statistically significant difference between attempted and achieved flap thickness, measured either by intraoperative ultrasound pachymetry or postoperative Visante OCT.
Keywords: refractive surgery: comparative studies • laser