Histopathology of ultrashort pulsed laser retinal damage: Changing retinal pathology with variation in spot-size for near-infrared laser lesions
Purpose: We wish to identify the change in extent of retinal tissue injury due to varying the spot size at the retina of ultrashort laser pulses. Methods: We compared the effects of delivery of near infrared (1060 nm) single laser pulses to an 800 micron diameter retinal spot to previously reported laser retinal effects. We examined macular lesions 24 hours after delivery of near-infrared (1060 nm wavelength) ultrashort laser to 804 micron spot-size, using fundus examination, fundus photographs and fluorescein angiograms. Using light microscopy, we examined sections of these lesions obtained 24 hours after laser delivery. The degree of retinal damage was compared to our data published previously by using a modified version of our previous grading scale. Results: The 150 fs near infrared, large spot laser lesions were remarkable in their clinical and pathological appearance. The lesions, rather than centering on a single focal spot of pallor as typically seen in pulsed laser lesions of the retina, demonstrated a spotted pattern of multiple focal lesions across the area of laser delivery. There was also choroidal damage in several eyes but the Bruch's membrane remained intact. Although there was choroidal damage in the 150 fs near infrared wavelength small spot laser lesions there was not significant thermal spread. The small spot ultrashort visible wavelength showed no significant thermal spread and no choroidal damage. Conclusions: Larger spot-size demonstrated a broader area of damage than that of the smaller spot-size and different choroidal effect when compared to smaller sized lesions.
Toth, CA; Winter, KP; McCall, MN; Rockwell, BA; Cain, CP
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