Effect of trabeculectomy on retrobulbar circulation and visual field progression in patients with primary open-angle glaucoma

BACKGROUND The purpose of this study was to investigate the relationship between retrobulbar circulation and visual field change in eyes with primary open-angle glaucoma following unilateral trabeculectomy. METHODS Twenty-one patients with primary open-angle glaucoma were prospectively enrolled. Retrobulbar circulation was evaluated using color Doppler imaging. The peak systolic velocity, end-diastolic velocity, and resistive index were evaluated in the central retinal artery, temporal site of the short posterior ciliary artery (t-SPCA), and nasal site of the short posterior ciliary artery (n-SPCA). Visual field examinations were performed using a Humphrey visual field analyzer before surgery and trimonthly for 12 months postoperatively. RESULTS In the operative eyes, the end-diastolic velocity was significantly increased in the central retinal artery (P = 0.005, analysis of variance), t-SPCA (P = 0.005), and n-SPCA (P = 0.027). The resistive index was significantly decreased in the central retinal artery (P = 0.003), t-SPCA (P = 0.000), and n-SPCA (P = 0.010) postoperatively compared with preoperatively. The nonoperative contralateral eyes did not show a significant change in end-diastolic velocity or resistive index for either the SPCA or central retinal artery. The mean deviation slope in the operative eyes (-0.26 ± 0.64 dB/year) was significantly slower than that in the nonoperative eyes (-0.65 ± 0.70 dB/year; P = 0.047, Mann-Whitney U test). CONCLUSION These results suggest that trabeculectomy improves the retrobulbar circulation and prevents the progression of visual field changes in patients with primary open-angle glaucoma.