Abstract
Abstract: :
Purpose: The role of oxidative stress in acute laser induced retinal injury (and many other retinal disease/injury modalities) has been long suspected. These experiments were conducted to determine the effect of a single dose treatment with a powerful anti-oxidant, N-acetylcysteine (NAC), on temporal development of retinal laser injury. We utilized the snake eye / Scanning Laser Ophthalmoscope (SLO) model, an invivo, non-invasive ocular imaging technique with the ability to image cellular changes in the retina. Methods: This experiment was a placebo matched, crossover design experiment to determine the treatment effect of a single dose NAC (150mg/kg, IP in sterile saline) on the size and development of laser induced retina lesions. 12 animals received 5 laser exposures per eye. Half received NAC or placebo, IP injection, 30 minutes post exposure and half were treated 2 hours post exposure. Retinal images were taken using a Rodenstock cSLO and digitally recorded at 1, 6, 24 hrs, and 3 weeks post exposure. Lesions were measured from these images by two raters blind to the conditions of each image. Measures of affected retinal area and counts of missing or damaged photoreceptors were made. Laser exposures were made with a coaxially aligned Nd:VO4 DPSS, 532nm laser. Shuttered pulses were 20msec X 50 mW; 1mJ each. Results: In the measurement of retinal area affected, treated eyes showed a beneficial effect overall(Total lesion area in placebo eyes was 118%, 112% and 116% [P=0.0155, 0.005, 0.0323]of NAC treated eyes at 6hr, 24hr and 3wks respectively). In the counts of missing and damaged cells there was a similar beneficial effect in the overall group(3 wk. Total Cells means; 42.2 Placebo, 37.5 NAC, p=0.01744). When the two different times of drug administration were analyzed separately, the placebo and treatment significance was reduced or absent. Conclusion: These experiments show that oxidative stress plays a role in laser induced retinal injury. The ability to observe in histological detail and quantify retinal damage with this model are demonstrated. NAC shows promise as a potential therapeutic tool.
Keywords: 554 retina • 454 laser • 321 antioxidants