Changes in the vitreous body pH of pigs after retinal xenon photocoagulation.

In an unpaired study, in vivo measurements of pH in vitreous were performed on normal pig eyes and pig eyes treated with retinal xenon photocoagulation. In one group (n = 7) the mean vitreal pH was 7.29 at a mean arterial pH of 7.41. In the other group (n = 8) two to three weeks after retinal xenon photocoagulation, a significant increase in mean vitreal pH of 0.06 to 7.35 (P less than 0.01) was observed at a similar arterial pH. Induced hypercapnia resulted in a decrease in pH vitr. and induced hypocapnia in an increase, with similar changes in pH art. The respiratory pH changes were similar in the two groups. These findings allow one to assume that, as a result of retinal photocoagulation, a change in the retinal metabolism is induced, either by a change in the relationship between aerobic and anaerobic metabolism or as a result of a general reduction of the metabolic activity.