Optic nerve head blood flow using scanning laser Doppler flowmetry after laser in situ keratomileusis.

Abstract

To investigate ocular blood flow changes following laser in situ keratomileusis (LASIK) in myopic eyes. Seventeen eyes of ten myopic patients were included in the study. Mean age of the seven men and three women was 29.1+/-2.5 years. Mean spherical equivalent refraction was -7.70+/-2.52 D. LASIK was performed with the Hansatome microkeratome and Summit SVS Apex excimer laser. Optic nerve head blood flow was measured by using the Heidelberg Retinal Flowmeter preoperatively and postoperatively at 1 day, 1 week, and 1 month. Preoperative ocular blood flow data (blood flow, volume, velocity) were compared with postoperative data using variance analysis. Correlation analysis was performed for age of patients, suction time, and ocular blood flow data. Mean suction time was 19+/-7 seconds. There was no significant correlation between suction time, age, and ocular blood flow. We found an increase in blood flow at the lamina cribrosa taken 1 day postoperatively (P=.04). Blood flow returned to preoperative values at the 1-week and 1-month measurements in the lamina cribrosa region. There was no significant change in ocular blood flow data in the neuroretinal rim except an increase in velocity at the lower nasal quadrant on postoperative day 1 (P=.03). LASIK caused a temporary increase in blood flow at the lamina cribrosa region of the optical nerve head in healthy myopic eyes. The increase in blood flow may suggest a compensatory change for maintaining blood flow in the ocular nerve head following LASIK-induced ischemia.