Retinal oxygen saturation and retinal vessel diameter in glaucoma patients before and after trabeculectomy

PURPOSE: To compare retinal vessel oxygen saturations and diameters before, 1 and 3 months after trabeculectomy.

METHODS: Retinal oxygen saturations and vessel diameters were obtained using retinal oximetry. The effect of the postoperative intraocular pressure (IOP) decrease on the arteriovenous difference (AV-difference) was evaluated, adjusting for mean defect (MD). The impact of trabeculectomy on AV-difference was compared between lowest (Q1) and highest (Q4) MD quartiles. Paired t-test, linear regression and Welch's t-test were applied.

RESULTS: Of 72 enrolled participants, 64 eyes of 64 participants were included. Arteriolar oxygen saturations were unchanged (97.4 ± 4.9% preoperatively, 98.1 ± 6.0% 1 month [p = 0.053], 98.2 ± 6.8% 3 months postoperatively [p = 0.154]). Venular saturations were also unchanged (62.0 ± 9.5% preoperatively, 61.7 ± 8.0% 1 month [p = 0.505], 61.3 ± 10.6% 3 months postoperatively [p = 0.685]). No significant difference in AV-difference occurred. Arteriolar diameters were unchanged 1 month postoperatively (109.7 μm ± 16.2 vs. 110.9 μm ± 19.3 [p = 0.80]) but decreased to 106.0 μm ± 15.7 3 months postoperatively (p = 0.012). Venular diameters increased 1 month postoperatively (152.8 μm ± 21.3 vs. 147.7 μm ± 20.0 [p = 0.034]) but not 3 months postoperatively (148.6 μm ± 24.8; p = 0.893). No association between postoperative IOP decrease and postoperative MD-adjusted AV-difference was found (p = 0.380). No significant change in AV-difference between Q1 and Q4 (p = 0.18) was found.

CONCLUSION: Retinal oxygen saturations remained stable, whereas vessel diameter changes occurred after trabeculectomy, probably reflecting alterations in IOP and perfusion pressure.