Abstract
Objectives
To correlate pterygium size and induced corneal astigmatism using a computerized
corneal topographic analysis system.
Patients and Methods
This study was conducted at Al-Shifa Eye Trust Hospital, Rawalpindi from May 2004 to
November 2004. In one eye of 60 patients with primary pterygium, size of Pterygium was
measured in millimeters from the limbus (horizontal length) by the beam of a Hag-Streit
900 Slit Lamp Microscope. Corneal astigmatism (diopters) was measured with the help of
Video Keratoscope model: HS-Keratograph CTK 992 (HAAG-STREIT).
Results
There were 48 (80%) males and 12 (20%) females. In Group A, the mean size of
pterygium was 1.24mm±0.379 and mean astigmatism was –1.165D±0.849 SD
(p=0.076). In Group B, the mean pterygium size was 2.84mm±0.557 and mean
astigmatism was –3.46D±1.441 SD (p=0.01). In Group C, the mean pterygium size was
4.833mm ±0.586 and mean astigmatism was –5.9D±0.265 SD (p=0.05). There were 37
eyes (61.7%) in Group A, 20 eyes (33.3%) in Group B and 3 eyes (5%) in Group C.
Conclusion
Pterygium size has direct correlation to the amount of induced astigmatism. The
correlation is stronger in the pterygia of moderately advanced group (Group B, 2.1-
4mm) as in this group the pterygium starts encroaching on the visual axis

Key words: Pterygium, Astigmatism, Corneal Topography.