The aim of the present study was to investigate the association between blood reflux in Schlemm's canal (SC) and the decrease of intraocular pressure (IOP) after selective laser trabeculoplasty (SLT) in primary open-angle glaucoma (POAG). To verify this, 35 eyes from 25 POAG patients were enrolled. All eyes underwent 360° whole-circle gonioscopy via a three-mirror lens, prior to undergoing 360° SLT. The four quadrants of the examined eye were individually compressed by the lens, and the presence of blood reflux in SC after removal of the pressure was recorded. Eyes with no blood reflux in any quadrant were assigned to the negative group, while the others were assigned to the positive group. Patients were evaluated at baseline, at 1 and 2 weeks, and at 1, 3 and 6 months after SLT. The results indicated that in the reflux-positive (21 eyes) and -negative (14 eyes) group, a significant IOP decrease was seen at 1 and 2 weeks, and at 1 and 3 months after SLT as compared with that pre-SLT IOP (P<0.01). In the negative group, the IOP at 6 months after SLT was not significantly different (P>0.05), while the positive group still exhibited a significant decrease in IOP compared with that at baseline (P<0.01). The positive group also presented with a greater decline in IOP at 1, 3 and 6 months compared with that in the negative group (P<0.05). A positive correlation between the number of quadrants with blood reflux in SC and the percentage decrease in IOP after SLT was identified in the positive group (P<0.05). In conclusion, blood reflux in SC was positively correlated with the decrease in IOP after SLT in POAG (Trialapproval number, K-2014-013).
Keywords: Schlemm's canal; blood reflux; intraocular pressure; primary open-angle glaucoma; selective laser trabeculoplasty.