The Effect of Experimental Ocular Hypertension on the Electroretinogram in Laser Treated Rabbit Eyes

Kim, Yoon duck; Kim, Woo Jung; Hyung, Sung Mln; Lee, Jaeheung

Abstract

The argon laser is widely used to coagulate the diabetic retina in order to inhibit the progression of diabetic retinopathy. To compare the electrophysiological changes of the photocoagulated retina according to the level of intraocular pressure(IOP), the right eyes of 24 pigmented rabbits underwent retinal photocoagulation with an argon laser. Retinal function was assessed electroretinographically at 4 weeks after retinal photocoagulation before treatment and under elevated IOP(40 mmHg, 60 mmHg, 80 mmHg) for 4 hours. In the 40 mmHg group, the amplitude of the a-, b-, oscillatory potentials(OPs) of the photocoagulated eyes showed a more rapid drop than the control eyes, and there was no recovery stage seen in the control eyes. In the 60 mmHg group the amplitude of the a-wave, b-wave, and OPs of photocoagulated eyes showed a rapid drop and were abolished after 3.5 hours, but that of the control eyes showed biphasic changes; first, a rapid drop with the same velocity as the photocoagulated eyes during the first 2 hours, then a steady stage for the last 1.5 hours. In the 80 mmHg group, electroretinogram was totally abolished within 20 minutes after elevation of IOP in both eyes. The above results showed that the photocoagulated eyes treated 4 weeks ago were more vulnerable to elevated IOP than the control, healthy eyes.