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.