Abstract

Pterygium is a common ocular surface disorder characterized by fibrovascular tissue growth from the conjunctiva onto the cornea, frequently causing corneal astigmatism that can significantly impact visual acuity and quality of life. This prospective study aimed to evaluate the relationship between pterygium size and the degree of corneal astigmatism before and after surgical excision, and to assess the visual outcomes following pterygium removal. A total of 180 patients with primary pterygium were enrolled and categorized into three groups based on pterygium size: small (n=60, <2mm from limbus), medium (n=65, 2-4mm from limbus), and large (n=55, >4mm from limbus). All patients underwent comprehensive ophthalmic examination including corneal topography, keratometry, and visual acuity assessment before and at 1, 3, and 6 months after pterygium excision with conjunctival autograft transplantation. Preoperatively, corneal astigmatism increased significantly with pterygium size, with mean values of 1.2±0.4 D, 2.8±0.7 D, and 4.6±1.2 D for small, medium, and large pterygia, respectively (p<0.001). Following surgical excision, significant reduction in corneal astigmatism was observed in all groups at 6 months postoperatively, with reductions of 0.8±0.3 D, 2.1±0.6 D, and 3.4±1.0 D for small, medium, and large pterygia, respectively (all p<0.001). The percentage reduction in astigmatism was greatest in the large pterygium group (73.9%) compared to medium (75.0%) and small (66.7%) groups. Best-corrected visual acuity improved significantly in all groups, with the greatest improvement observed in patients with large pterygia (from 0.45±0.12 to 0.08±0.05 logMAR, p<0.001). Corneal topographic analysis revealed that with-the-rule astigmatism was most common in all groups, and the axis of astigmatism remained relatively stable after surgery. The study demonstrates a strong positive correlation between pterygium size and preoperative corneal astigmatism (r=0.84, p<0.001), and confirms that surgical excision effectively reduces corneal astigmatism, with larger pterygia showing greater absolute reduction but similar percentage improvement. These findings support the recommendation for early surgical intervention in pterygium cases to minimize corneal distortion and optimize visual outcomes.