Macular blood flow changes in branch retinal vein occlusion examined by optical coherence tomography angiography variable interscan time analysis

Abstract

Purpose:To examine the relationship between changes in retinal blood flow and the recurrence of macular edema in eyes with branch retinal vein occlusion.Methods:This observational study included 32 eyes in 32 patients (18 men and 14 women) with branch retinal vein occlusion who visited the Department of Ophthalmology at Kyoto University Hospital (February 2021-November 2021). At the time of inclusion in the study, each patient underwent optical coherence tomography angiography on a macular area measuring 4 × 4 mm2. For variable interscan time analysis, different interscan times were set at 7.6 (IST7.6) and 20.6 ms (IST20.6) for the optical coherence tomography angiography. The parafoveal vessel densities were measured sectorally at IST7.6 and IST20.6, and their relationship with the longitudinal changes evident in the retinal thicknesses during the variable interscan time analysis examination and 2 months later was evaluated.Results:The parafoveal vessel densities in the affected sector was significantly greater at IST20.6 than at IST7.6 (P = 0.011). At 2 months after the variable interscan time analysis examination, 6 patients (19%) showed recurrence of macular edema involving the fovea. The difference in the parafoveal vessel densities (IST20.6 - IST7.6) in the affected sector was significantly associated with longitudinal retinal thickening in the corresponding parafovea (P = 0.020) and fovea (P = 0.014).Conclusion:In eyes with branch retinal vein occlusion, optical coherence tomography angiography variable interscan time analysis facilitated the detection of retinal blood flow changes that might be predictive for the recurrence of macular edema.