Minimum Visible Retinal Lesions from Pico- and Femtosecond Laser Pulses

摘要

Threshold measurements for Minimum Visible Lesions (MVL) at the retina arereported for femtosecond (fs) and picosecond (ps) laser pulses in Rhesus monkey eyes using visible wavelengths. The 50% probability for damage (ED50) dosages are calculated for 1 hour and 24 hour post-exposures at the 95% confidence level. The ED50 values are found to decrease with pulsewidth down to 600 fs. At 90 fs the ED50 dosages were noted to increase slightly when compared with the 3 ps and 600 fs values. Fluorescein angiography (FA) was accomplished at both 1 hour and 24 hour post-exposure and did not demonstrate lower threshold for damage, which has been the case for MVL's created with longer pulse durations (nanoseconds). At the 90 fs pulse duration, MVL's were not observed below 0.1 j. At energies greater than 0.1 J, both MVL and the absence of MVL's were observed up to 1.4 J. Above 1.4 J all energies delivered showed MVL development. Out of 138 data points taken at 90 fs, 94 were between 0.1 and 1.4 J, and the observed lesions are distributed with approximately 50% probability throughout this energy range.