Studying the type of astigmatism in patients with corneal pterygium referring to ophthalmology clinics of Northwestern Iran

Pterygium is a prevalent ocular disease which is often asymptomatic but can cause photophobia and tearing and decrease vision through progression towards the visual axis or create astigmatism. Our aim in this study is to determine the type of astigmatism in patients suffering from corneal pterygium referring to Imam Hospital during the second six months of the year 2010. Methods: All patients referring to the ophthalmology clinics of the education-treatment center of Imam in Urmia were non-randomly entered into the plan and the rate and type of their astigmatism were studied. The patients’ informationsuch as demographics, urban and rural, occupation, the amount and type of astigmatism was determined by Autorefra ctometer set (with-the-rule or against-the-rule astigmatism) and entered into the check-lists. Results: Among 100 studied patients, 55 patients (55%) were men and 45 (45%) were female.For 32 cases (32 %) right eyes, 38 (38%), left eyesand 30 cases (30 %), both eyes suffered from Pterygium. In comparison of the type of astigmatism between eyes with pterygium and healthy eyes, it was observed thatout of 130 eyes suffering from pterygium, 83 cases (63.8%) hadwith-the-rule astigmatism, 13 cases (10%) against-the-rule astigmatism and 34 cases (26.2%) hadobliqueastigmatism.Out of 67 healthy eyes, 30 cases (44.8%) werewith-the-rule astigmatism, 12 cases (17.9%) against-the-rule astigmatism and 25 ones (37.3%) obliqueastigmatism.Given theChi-Square statistic test, there is a significant difference between the types of astigmatism of eyes with pterygium and healthy eyes (P=0.03). The average rate of astigmatism in 130 eyes with pterygium was -1.52 ± 1.32diopters and -1.04± 1.41dioptersin 67 healthy eyes. According to the t-test, there isa significant statistical difference between the rate of astigmatism in eyes suffering from pterygium and that in the healthy eyes (P=0.01). Conclusions: Pterygium causes the creation of with-the-rule astigmatism and also has a great impact on the rateof astigmatism.