Purpose:
According to Poiseuille’s law, lowering intraocular pressure should lead to increased retinal blood flow. If constant oxygen consumption is assumed, the oxygen saturation in retinal vessels should rise. In this study the effect of glaucoma surgery on retinal oxygen saturation was investigated.
Methods:
The retinal oximeter estimates hemoglobin oxygen saturation in retinal vessels. The oximeter is composed of a fundus camera, beam splitter, light filters and specialized software. Oximetry was performed in 1st an 2nd degree retinal vessels before glaucoma operation and again approx. one month after operation. All patients with OAG with or without pseudoexfoliation, undergoing glaucoma surgery in Iceland in a 6 month period were offered to participate in the study. Twenty-five patients were measured before and after surgery. Six patiens were excluded from analysis because of poor optical quality of the eye. Statistical analysis was performed with two-way repeated measures ANOVA with Bonferroni post-tests.
Results:
The table below shows oxygen saturation (means±SD), 19 individuals.The 2% rise in oxygen saturation in arterioles in operated eyes is statistically significant (p<0.05). Intraocular pressure (IOP) decreased after operation in all cases, from 25±9mmHg mean±SD) before operation to 10±4mmHg after operation.
Conclusions:
Oxygen saturation in retinal arterioles increases slightly in retinal arterioles with glaucoma surgery but venous saturation remains stable.
Keywords: oxygen • intraocular pressure • retina