Changes Of Retinal Blood Flow After Selective Laser Trabeculoplasty For POAG By OCTA

Objective: To investigate the effects of selective laser trabeculoplasty(SLT)on fovea avascular area(FAZ),peripapillary and macular vascular density in primary open angle glaucoma(POAG)patients using optical coherence tomography angiography(OCTA).Methods: This was a prospective study performed at the Joint Shantou International Eye Center of Shantou University & the Chinese University of Hong Kong.A total of 21 eyes of 20 POAG patients admitted from June 2020 to April 2021 were included.All patients were successfully completed selective laser trabeculoplasty.Topcon OCTA was performed 1 hour before SLT and 1 hour,1 day,1 week and 1 month after the procedure.A 6 mm*6 mm grid was chosen to scan the macular region and 4.5mm * 4.5 mm grid to nerve head.The superficial and deep macular layer,the optic nerve head(ONH)layer and the radial peripapillary capillaries(RPC)layer were selected and Image J software was used to calculate the FAZ area,and the total,upper,lower,nasal and temporal vascular density。Results: There were 11 males and 9 females with an average age of49.95 ± 15.66 years.The number of anti-glaucoma drugs was 2.19 ± 1.17.The mean preoperative IOP was 20.0 ± 5.15 mm Hg,1 hour postoperative IOP was23.0 ± 5.88 mm Hg(+15%,P<0.0001),1 day was 14.2 ± 4.71 mm Hg(-29%,P<0.0001),1 week was 15.4 ± 5.10 mm Hg(-15.8%,P<0.0001),1 month was 12.9 ± 4.31 mm Hg(-28%,P<0.0001).The average vessel density of superficial and deep vessels in the macular area,the ONH layer and RPC layer around the optic disc of the superior,inferior,nasal and temporal sides were not significantly different from the preoperative vessel density at 1 hour,1 day,1 week and1 month after operation(P > 0.09 in the macular area and P > 0.19 in the optic disc).Conclusion: Although the intraocular pressure of POAG patients significantly decreased 1 month after SLT treatment,there were no significant changes in FAZ area,peripapillary and macular vascular density.Further pursuit of this topic appears to be warranted to understand the exact mechanism and clinical relevance.