Trabeculectomy is associated with retrobulbar hemodynamic changes : a color Doppler analysis

To determine whether color Doppler hemodynamic changes occur in the retrobulbar circulation after trabeculectomy. The authors prospectively enrolled 20 patients undergoing trabeculectomy and performed color Doppler imaging of both eyes before surgery and then at approximately 2-, 5-, and 14-week intervals after surgery. The systolic maximum velocity, mean velocity, end-diastolic velocity, and vascular resistance (resistance index) of the central retinal artery, nasal and temporal short posterior ciliary arteries, and ophthalmic arteries were determined. Statistical comparison of the preoperative and postoperative measures were performed on both the operative and nonoperative eye using the paired Student's t test. A statistically significant increase was observed in the mean and end-diastolic velocity and a significant decrease in the vascular resistance of the central retinal artery and both short posterior ciliary arteries at nearly all postoperative intervals (25 of 27 preoperative and postoperative comparisons; P < 0.05) The ophthalmic artery, while showing an increased velocity at all intervals, only attained a statistically significant increase in one of three postoperative intervals for mean velocity and two of three intervals for end-diastolic velocity (P < 0.05). There were no notable changes in resistance. The nonoperative eye did not show a statistically significant change in velocity or in resistance in the central retinal artery or either nasal or temporal short posterior ciliary artery at any interval (0 of 27 preoperative and postoperative comparisons for mean velocity, end-diastolic velocity, and resistance index.) Sustained increases in mean velocity and end-diastolic velocity and decreases in resistance index were observed in the central retinal artery and the short posterior arteries with clinically attainable reductions in intraocular pressure after trabeculectomy in patients with chronic glaucoma. These findings are consistent with, but not diagnostic of, increased blood flow through these vessels.