Comparison of astigmatism changes before and after pterygium surgery

Abstract Introduction: Pterygium, a common ocular condition, is characterized by fibrovascular tissue overgrowth from the conjunctival-limbal region onto the cornea. It often induces corneal astigmatism due to mechanical distortion and tear film irregularities, significantly impacting visual quality. Surgical excision remains the definitive treatment, particularly for progressive cases affecting vision. Materials and Methods: This prospective observational study was conducted on 20 patients with pterygium at The Oxford Medical College. Patients with astigmatism >1 D and pterygium encroachment >2 mm onto the cornea were included. Comprehensive preoperative assessments, including slit-lamp examination, keratometry, and corneal topography, were performed. Postoperative assessments at 1 week, 2 weeks, 4 weeks, and 6 months included corneal topography to evaluate changes in astigmatism. Data were analyzed using paired t-tests or Wilcoxon signed-rank tests, with P < 0.05 considered statistically significant. Results: The mean pterygium size was 3.5 ± 0.7 mm, with a mean area of 12.5 ± 3.2 mm2 and 45.5% ±12.1% corneal extension. Corneal astigmatism decreased from 3.80 ± 0.86 D preoperatively to 2.98 ± 0.68 D at 1 week postsurgery (P = 0.08) and further reduced to 2.12 ± 0.56 D at 4 weeks (P < 0.001). At 6 months, astigmatism improved to 1.98 ± 0.62 D (P < 0.001). A strong positive correlation was noted between pterygium area and astigmatism (r = 0.65, P < 0.01). Conclusion: Pterygium excision significantly reduces induced astigmatism and improves corneal topography, with refractive stability achieved by 6 months postsurgery. Early surgical intervention for pterygium encroaching >2 mm on the cornea is crucial to prevent long-term corneal distortion and enhance visual outcomes.