Rates of visual field loss before and after trabeculectomy.

. Purpose:  To compare the rates of change in the visual field (VF) in patients with glaucoma before and after trabeculectomy. Methods:  Of 52 eyes of 52 patients with different types of chronic glaucoma who underwent first trabeculectomy were evaluated retrospectively. Pre- and postoperative-automated visual fields measured by the same technique were compared to detect differences in rates of change. Rates of VF loss before and after trabeculectomy were calculated using mean deviation (MD). Linear mixed models were used to compare the rates of change in the VF before and after trabeculectomy. Results:  The mean follow-up period pre- and post-trabeculectomy was 3.9 years (min 0.9, max 10.7) and 3.8 years (min 2.0, max 8.0), respectively. The intraocular pressure (IOP) decreased from 18.1 mmHg (SD = 4.7) before trabeculectomy to 11.1 mmHg (SD = 2.9) at the last follow-up after trabeculectomy. The rate of MD loss was reduced with 56% on average, from −0.36 dB/year before surgery to −0.16 dB/year after surgery (p = 0.15). Conclusion:  Trabeculectomy considerably decreased the rates of change in the glaucomatous visual field.