Comparison of quantitative measurement of macular vessel density before and after inferior oblique muscle–weakening surgery: An optical coherence tomography angiography study

Purpose To investigate hemodynamic changes in retinal and choroidal vasculature after surgical inferior oblique (IO) weakening through optical coherence tomography angiography (OCTA). Methods The medical records of patients who underwent unilateral IO-weakening surgery at a single institution were retrospectively reviewed. Patients who had OCTA measurements before surgery and on postoperative days 7 and 30 were included. Vessel density was determined for the superficial capillary plexus (SCP), deep capillary plexus (DCP), the choriocapillaris (CCP) and the foveal avascular zone (FAZ). Results The study included 72 eyes of 36 patients. Fellow eyes were used as a control group. The preoperative and postoperative week 1 and month 1 mean central vessel densities of the SCP were 20.48% ± 3.52%, 20.68% ± 3.83%, and 23.56% ± 5.65%, respectively, in the operated eye; those of the DCP were 16.72% ± 3.33%, 16.08% ± 4.65%, and 20.85% ± 7.09%, respectively. The mean FAZ areas were 341.29 ± 88.04 μm2, 341.30 ± 98.25 μm2, and 316.02 ± 74.61 μm2, respectively. We detected no significant changes in SCP, DCP, and FAZ in the postoperative period. The mean central vessel density of the CCP increased significantly from the preoperative level of 54.06% ± 2.86% to 55.55% ± 2.63% at postoperative week 1, but there was no significant difference between baseline and postoperative month 1 (P = 0.001 and P = 0.515, resp.). Conclusions IO muscle surgery does not seem to cause alterations in retinal hemodynamics, although it can transiently increase the central vessel density of the CCP during the early postoperative period.