Evaluation of changes in refractive errors before and after trabeculectomy and shunt surgery

Purpose: The aim of the present study was to investigate the change rate of astigmatism and axial, myopia, and hypermetropia in trabeculectomy and shunt surgery. Patients and Methods: In this comparative study, two groups of 16 patients with an average age of 52.4±8.9 and 94.6±6.7 respectively underwent trabeculectomy and shunt surgery. The changes of reactive error were compared before the surgery and 1 week, 1 month, and 3 months after the surgery. Data from the two groups were analyzed via Friedman and Mann–Whitney tests. Results: Average of intraocular pressure (IOP) before, and 1 week, 1 month, and 3 months after trabeculectomy is 31.31±7.6, 9.8±2.8, 10.5±1.29, 10.9±1.26 (P<0.05) and shunt is 36.06±10.32, 13.5±3.3, 11.68±2.21, 11.18±1.27 (P<0.05). Average astigmatism in trabecu-lectomy is −1.00±0.59, −6.00±1.9, −2.21±1.18, −1.37±0.62 (P<0.05) and in shunt it is −0.89 ±0.46, −1.56±1.62, −1.51±1.46, −1.07±0.85 (P>0.05). Percent WRT astigmatism in trabecu-lectomy is 37.5, 100, 37.5, 31.25 and in shunt it is 43.75, 50, 50, 56.25 and average of spherical equivalence (SE) in trabeculectomy is −0.31±1.49, 1.43±1.94, 0.27±1.74, 0.04 ±1.46 (P<0.05) and in shunt it is 0.65±1.5, 1.03±2.03, −0.70±1.64, 0.62±1.54 (P<0.05). Astigmatism and axial comparisons between trabeculectomy and shunt with Mann–Whitney test were significant (P<0.05), but SE was not significant (P>0.05). Conclusion: The surgeries induced hypermetropia and reduction with the passing of time but astigmatism amount and percent of with-the-rule astigmatism in trabeculectomy were more than in shunt surgery.