To study the effect of pterygium excision on corneal curvature and contrast sensitivity

Abstract

Introduction: To evaluate the corneal astigmatism and contrast sensitivity before and after pterygium surgery and to study the relationship between amount of astigmatism and contrast sensitivity in various grades of pterygia. Material and Method: Sixty three eyes of 63 patients with primary pterygia were studied before and after surgery. The astigmatism induced by primary pterygium was measured by manual keratometer and contrast sensitivity by Pelli Robson chart. Preoperative and postoperative values were compared using paired t –test and ANOVA test. Result: Astigmatism decreased significantly following pterygium excision. The mean preoperative refractive cylinder decreased from 3.29±1.46 D to 1.49±0.82 D postoperatively. Surgical removal of pterygium caused a significant reduction in refractive astigmatism. The amount of astigmatism decreased significantly following pterygium excision in grade II , grade III and in grade IV. In grade I pterygium, decrease in the amount of astigmatism was not statistically significant (p=0.515). The contrast sensitivity increased significantly following pterygium excision. The mean preoperative contrast sensitivity increased from 1.49±0.21 to 1.70±0.20 postoperatively. Surgical removal of pterygium caused a significant improvement in contrast sensitivity. Conclusions: Surgical excision of pterygium improves contrast sensitivity, visual acuity and reduces astigmatism. Contrast sensitivity testing may provide additional objective methods for documenting impaired vision in patients with pterygium when Snellen visual acuity is minimally affected. Corneal astigmatism and contrast sensitivity values in patients with pterygia are useful indicators for the need of pterygium surgery or as indicators of surgical success.