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The effect of phacoemulsification on aqueous outflow facility
M A Meyer1, M L Savitt, E Kopitas
1Department of Ophthalmology, Loyola University, Chicago, Illinois, USA.
Objective:
Although control of intraocular pressure (IOP) after cataract 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 coefficient 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 receive either single- or two-quadrant conjunctival peritomy and phacoemulsification.
Main Outcome Measures:
Tonometry and tonography were assessed 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 11.4 months' (range, 10-13 months) follow-up were analyzed. Patients with reduced preoperative facility of outflow (as defined by C < or = 0.28 microliter/min/mmHg) showed a significant improvement from a mean preoperative value of 0.24 +/- 0.04 microliter/min/mmHg to 0.41 +/- 0.22 microliter/min/mmHg at 1 year (P = 0.002, N = 19). Among all patients, there was no significant change between mean preoperative C and last follow-up (0.39 +/- 0.23 vs. 0.46 +/- 0.38 microliter/min/mmHg, not significant [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 postoperative 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 significantly elevated IOP at 1 year compared to preoperative values (P = 0.02, N = 12). There were no significant differences detected regarding C or IOP between single- or two-quadrant peritomy groups.
Conclusions:
Outflow facility improves after phacoemulsification in patients with a reduced 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 facility or IOP after surgery.