Impact of Different Grades of Pterygium on Corneal Astigmatism and Visual Function

Background: Pterygium is a progressive ocular surface disorder characterized by a fibrovascular growth that extends from the conjunctiva onto the cornea. Its presence disrupts corneal curvature, inducing astigmatism and compromising visual function. Ultraviolet (UV) radiation exposure remains the most prominent risk factor, particularly in individuals with outdoor occupations. Understanding the correlation between pterygium severity and its impact on visual outcomes is critical to guide early intervention, prevent progression, and reduce the associated visual morbidity in affected populations. Objective: The objective of this study was to evaluate the impact of different grades of pterygium on corneal astigmatism and visual function in patients aged 20–60 years. Methods: A cross-sectional study was conducted at the Layton Rahmatulla Benevolent Trust (LRBT) Eye Hospital over six months. A total of 60 participants were recruited using convenience sampling. Inclusion criteria consisted of clinically diagnosed pterygium, while patients with other ocular or systemic diseases were excluded. Visual acuity was measured using the Snellen chart, pterygium grading was performed with slit-lamp biomicroscopy, and corneal astigmatism was assessed using an auto-refractometer. Best-corrected visual acuity (BCVA) was determined through subjective refraction. Statistical analysis was performed using SPSS v25, with Chi-square and Pearson correlation applied to assess associations. Results: The mean age of participants was 40.22 ± 12.6 years, with 53.3% males and 46.7% females. Outdoor workers represented 70% of the sample. Grade 1, 3, and 4 pterygium were equally prevalent (30% each), while Grade 2 accounted for 10%. Corneal astigmatism increased significantly with advancing pterygium grade (p<0.001), with 43.3% of participants showing astigmatism ≥1.75 D. Visual acuity improved from 25% achieving 6/6 before correction to 35% after correction, while 63.3% attained 6/9. Visual disturbances were frequent in 51.7% of patients, with eye irritation (28.3%), foreign body sensation (21.7%), and photophobia (20%) reported as the most common symptoms. A significant correlation was observed between pterygium grade and both spherical refractive error (p<0.001) and BCVA (r=0.536, p<0.001). Conclusion: This study found that increasing pterygium grade was significantly associated with higher corneal astigmatism, spherical refractive errors, and visual disturbances. These findings highlight the importance of early diagnosis, preventive measures, and timely intervention to minimize functional impairment and improve quality of life in affected individuals.