Surgically induced corneal astigmatism after fornix-based trabeculectomy
Abstract
Purpose
To evaluate the degree of surgically induced corneal astigmatism (SIA) following trabeculectomy and to investigate the relation of SIA with long-term reduction of intraocular pressure (IOP).
Methods
Fourty-four eyes of 44 patients undergoing fornix-based trabeculectomy were included in this single center, prospective trial. IOP, visual acuity (VA), corneal astigmatism, medication use and adverse events were recorded preoperatively and at 1, 3, 6 and 18 months postoperatively. Changes in corneal astigmatism were analysed using vector analysis. Pre- and postoperative parameters were compaired using one-sample t-test. Correlation between SIA and IOP were assessed using Pearson correlation coefficients.
Results
Vector analysis of corneal astigmatism revealed a significant increase in with-the-rule corneal astigmatism, reaching a maximum at 1 month postoperatively (1.15 ± 0.8 D, P < 0.001) followed by a gradual decline (0.87 ± 0.8 D, P < 0.001 at month 18). SIA at 1 month showed a borderline significant correlation with IOP reduction at 3 months (r = 0.315, P = 0.051). SIA at 3, 6 and 18 months did not correlate with reduction in IOP (P > 0.05). After a transient decline at 1 month after surgery, VA recovered to preoperative values at month 3 without need for adjustment of the optical correction.
Conclusions
Fornix-based trabeculectomy induces statistically significant with-the-rule astigmatism without affecting long term VA. In our population, maximum SIA, measured at 1 month postoperatively, showed a borderline significant correlation with reduction of IOP at 3 months.
