THE EFFECT OF PHACOEMULSIFICATION ON AQUEOUS OUTFLOW FACILITY

Objective: Although control of intraocular pressure (IOP) after catara ct extraction may be of critical importance, little is known regarding changes in facility of outflow in the early postoperative period, The effect of phacoemulsification and conjunctival peritomy size on the c oefficient of aqueous outflow facility (C) and IOP was studied, Design : Participants were assigned randomly to one of two treatment groups, Participants: Seventy-four patients with cataract and without evidence of glaucoma were studied. Intervention: Patients were randomized to r eceive either single- or two-quadrant conjunctival peritomy and phacoe mulsification. Main Outcome Measures: Tonometry and tonography were as sessed before surgery and at 1 day, 1 week, 6 weeks, and 1 year after surgery by a masked observer. Results: Fifty patients with a mean of 1 1.4 months' (range, 10-13 months) follow-up were analyzed. Patients wi th reduced preoperative facility of outflow (as defined by C less than or equal to 0.28 mu l/min/mmHg) showed a significant improvement from a mean preoperative value of 0.24 +/- 0.04 mu l/min/mmHg to 0.41 +/- 0.22 mu l/min/mmHg at 1 year (P = 0.002, N = 19). Among all patients, there was no significant change between mean preoperative C and last f ollow-up (0.39 +/- 0.23 vs. 0.46 +/- 0.38 mu l/min/mmHg, not significa nt [ns], N = 50), Furthermore, there was no significant change between mean preoperative and final IOP (23.7 +/- 4.1 vs. 23.3 +/- 3.9 mmHg, ns, N = 50). There was a significant elevation of mean IOP on postoper ative day 1 to 27 +/- 6.2 mmHg (P = 0.001, N = 50), Patients with IOP elevations greater than 8 mmHg on postoperative day 1 had significantl y elevated IOP at 1 year compared to preoperative values (P = 0.02, N = 12), There were no significant differences detected regarding (= or IOP between single- or two-quadrant peritomy groups. Conclusions: Outf low facility improves after phacoemulsification in patients with a red uced preoperative coefficient of aqueous outflow. Postoperative day 1 IOP is significantly elevated after phacoemulsification. Conjunctival peritomy size does not appear to play a role in aqueous outflow facili ty or IOP after surgery.