Evaluation of Changes in Refractive Errors Before and After Trabeculectomy and Shunt Surgery

The aim of the present study was to investigate the change rate of astigmatism and axial, myopia, and hypermetropia in trabeculectomy and shunt surgery.

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.

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 trabeculectomy 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 trabeculectomy 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).

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.