Abstract
Purpose:
To investigate the change in corneal astigmatism after trabeculectomy.
Methods:
Between January and April 2012 patients who underwent a primary trabeculectomy were included in this prospective study. We measured visual acuity (VA), automated keratorefractometry, and intraocular pressure (IOP) pre- and postoperatively at month 1, 3 and 6. Changes in astigmatism were quantified using the vector analysis described by Cravy (Ophthalmic Surgery 1979; 10: 38-49). A Friedman test and a linear model for longitudinal measures were used to compare changes in refraction and IOP. A binomial test was used to compare the proportion of eyes with a shift of astigmatism with- or against the rule (WTR or ATR).
Results:
Fifty two eyes (51 patients) were included. The mean (±SD) IOP decreased from 17.5 ±5.41 mmHg preoperatively to 9.7 ±3.96 mmHg after 6 months (p<0.001). The mean logMAR VA was 0.17 ±0.22 preoperatively and 0.14 ±0.14 after 6 months (p=0.9). After 6 months 32/47 eyes showed a shift of astigmatism WTR (p=0.02). The median difference in cylinder after 6 months for all the eyes was +0.5D (range 0-4D) (p=0.004).The mean axis of the positive cylinder changed from 169° ±148° to 135° ±146° after 6 months (p=0.12). The mean spherical equivalent changed from −0.47D ±2.27D to −0.07D ±1.93D (p=0.15).
Conclusions:
Trabeculectomy induced a small but statistically significant shift of astigmatism with the rule after 6 months. Spherical equivalent didn’t change compared with preoperatively. Most often glasses will not need to be changed after trabeculectomy.
Keywords: 765 wound healing •
428 astigmatism •
568 intraocular pressure