Abstract
Purpose: :
To assess rates of global visual field change before and after trabeculectomy in patients with glaucoma.
Methods: :
Visual field data from patients followed up in the Eye Care Centre at the QEII Health Sciences Centre, Halifax were reviewed. Patients who had 10 or more Humphrey visual fields (full threshold or SITA standard) were assessed for eligibility. Patients were enrolled if they had trabeculectomy or phaco-trabeculectomy and if at least 5 visual fields before and after surgery were available for analysis. Linear regression analysis was used to calculate mean deviation (MD) rates of change before and after surgery.
Results: :
Data from 38 eyes of 33 patients were analyzed. Mean (SD) age at surgery date was 70 (9.3) years. Mean number of visual fields was 26.6 (range, 11 - 41) fields. Mean number of preoperative visual fields was 17.4 (range, 5 - 32) fields. Mean number of postoperative visual fields was 9.2 (range, 5 - 22) fields. Mean follow-up was 8 (range, 1.8 - 15.4) years before surgery and 4.5 (range, 1.9 - 10.6) years after surgery.Mean MD of visual fields done before trabeculectomy was -8.2 (5.1). Mean MD rate decreased from -0.6 (1.0) dB/year before surgery to -0.2 (0.7) dB/year after surgery (60 % ; p= 0.14, Wilcoxon). Mean IOP was reduced from 17.6 (3.7) mmHg before surgery to 12.3 (3.8) mmHg after surgery (29.6 ± 19.1 %). In patients with preoperative MD slopes =< -0.5 dB/y (n=11), the mean (SD) MD rate decreased from -1.8 (1.2) dB/y before surgery to -0.4 (0.8) dB/y after surgery (77 % ; p= 0.013, Wilcoxon)
Conclusions: :
Rates of MD deterioration were, on average, less rapid after trabeculectomy. This difference, however, was not statistically significant. When only patients with a rapid rate of MD decline prior to surgery were analyzed, a significant reduction in the MD rate was observed.