THE EFFECT OF SODIUM FLUORESCEIN ON ARGON GREEN PHOTOCOAGULATION OF THE RETINA

Darryl Voight

Abstract

Fluorescein angiography is routinely performed prior to most laser photocoagulation of the posterior segment. Since sodium-fluorescein has well-known absorptive and photosensitizing properties, it may affect photocoagulation in the retina. The presence of sodium- fluorescein in the vascular bed of the retina, choriocapillaris, and choroid can, therefore, act as a target for laser energy thereby effectively lowering the threshold for retinal photocoagulation. In this study retinal photocoagulations were performed using a MIRA green argon laser (514.5nm) and a Volk QuadrAspheric fundus lens in Dutch Belted rabbits anesthetized with IM ketamine- xylazine. Photocoagulations were done with a 500 um spot size and a 100 msec duration and using gradually decreasing intensities (300 mW to 50 mW in 50 mW increments). Three sets of these intensity series were done (IE: prior to fluorescein injection, 2 minutes after injection and another 15 minutes later). IV injection of 0.5 ml of a 10% sodium- fluorescein solution was accomplished via an ear vein. The retinal burns were then examined and photographed immediately following and 48 hours after photocoagulation using a Nikon slit-lamp and Volk Area Centralis fundus lens. Photos taken immediately after the photocoagulation showed typical edematous whitening of the retina and were similar for the three groups. In the 48 hour observation, at higher beam intensities, the resultant burns showed extensive scarring and were similar between groups. However, in the lower intensity groups, the central area of the lesions showed scarring which was of a much smaller diameter than the beam size and probably represented central heating of the lesion. In particular, the lowest two exposures delivered after fluorescein injection demonstrated a halo of choroidal pigment disruption that could indicate enhanced choroidal photodamage possibly mediated by fluorescein absorption. This has significance to practitioners performing laser photocoagul

Details

Year: 1992

Program Number: Poster 26

Author Affiliation: n/a

Co-Authors: Annette Froehlich, Pierrette Dayhaw-Barker

Co-Author Affiliation: n/a

Room: Great Hall