The relationship between pterygium and corneal astigmatism

Objective:To assess the quantitative relationship between pterygium size and induced corneal astigmatism.Methods:45 patients(50 eyes) with primary pterygium were evaluated through refraction, corneal curvature measurement and pterygium size. The amount of astigmatism was compared pre- and post-surgery.Results:Pterygium can induce with-the-rule astigmatism. When pterygium extends 2.5～3mm into cornea, it will produce significant astigmatism.Conclusion:Once pterygium reach a critical size, they induce significant with-the-rule astigmatism. This finding helps to determine the surgery time.