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Prospective randomized comparison of one- versus two-site Phacotrabeculectomy two-year results
Yvonne M Buys1, Mary L Chipman, Barend Zack
1Department of Ophthalmology and Visual Sciences, Toronto Western Hospital, Toronto, Canada. y.buys@utoronto.ca
Purpose:
Previous studies have failed to find a significant difference in intraocular pressure (IOP) between one- and two-site phacotrabeculectomy. A possible explanation has been relatively small samples and short follow-up. We prospectively observed 80 patients for 2 years randomized to one- versus two-site phacotrabeculectomy with the primary outcome measure being IOP.
Design:
Prospective randomized controlled study.
Participants:
Eighty eyes were randomized and 79 underwent phacotrabeculectomy; 76 completed 24 months' follow-up.
Methods:
Eligible patients scheduled for phacotrabeculectomy were randomized to one- or two-site phacotrabeculectomy after giving informed consent. A sample size of 54 was calculated to detect a difference of 2 mmHg between the groups with a power of 80%. Data recorded included demographics, visual acuity, IOP, endothelial cell counts, glaucoma medications, phacoemulsification settings, iris manipulation, suture lysis, needling, and complications. Follow-up data were obtained at 3, 6, 12, and 24 months.
Main Outcome Measure:
Mean IOP at 24 months.
Results:
There were no significant differences between the groups preoperatively. Mean IOPs were 17.6 versus 17.6, 12.6 versus 12.5, 13.1 versus 11.7, 13.1 versus 12.7, and 12.5 versus 12.9 mmHg for one- versus two-site at baseline and 3, 6, 12, and 24 months. There was a significant lowering of IOP compared with baseline at all time points (P<0.05). There was no significant difference in mean IOP between the groups at any time. The mean number of glaucoma medications decreased from 3.0 in each group to 0.2 and 0.4 for one- and two-site, respectively, at 24 months (P = 0.20). At 3 and 12 months, the endothelial counts (cells/mm(2)) were significantly lower in the two-site group: 2333 versus 2207 (P = 0.17), 2239 versus 1938 (P = 0.01), 2180 versus 1934 (P = 0.04), and 2147 versus 1947 (P = 0.08) at baseline and 3, 12, and 24 months, respectively. The surgical time was significantly longer for two-site (48.1+/-7.8 minutes) compared with one-site (39.2+/-6.4 minutes; P<0.001).
Conclusion:
At 2 years after phacotrabeculectomy, there was no statistically significant difference in IOP between groups. Corneal endothelial cell counts were significantly lower in the two-site group at 3 and 12 months. Two-site surgery took significantly more time.