To survey the astigmatism types in patients with pterygium attended in Urmia ophthalmologic clinics (2010-2014).

All patients with pterygium assigned for study (non-randomized) and their astigmatism types and degree determined. Patients' information aggregated into the standard checklists including their demographic data, occupation, determined astigmatism type and value with refractometer (with/against-the-rule). Collected data showed by descriptive statistics (frequency percentage ,mean and variance indices). For determining the correlation between pterygium and astigmatism type ,chi-square test was applied.

100 patients surveyed including 55 males (55%) and 45 females (45%). 32 (32%) patients with right eye,38 (38%) left eye and 30 (30%)patients with both eyes pterygium evaluated. Comparing astigmatism type in the normal eye and eyes involved with pterygium showed that; from the 130 eyes with pterygium ,83 (63/8%) eyes were with the- rule astigmatism , 13(10%) eyes with against-the-rule astigmatism and 34 (26/2%) eyes with oblique astigmatism. From the 67 normal eyes ,30 (44/8%) eyes were with-the-rule astigmatism ,12(17/9%) eyes with against-the-rule astigmatism ,and 25 (37/3%) eyes with oblique astigmatism. Regarding to the chi-square analyze, astigmatism type in normal eye and eye with pterygium differred significantly (P=0.01).

Pterygium causes with-the-rule astigmatism and seriously affects the astigmatism value.