EFFECTS OF PTERYGIUM EXCISION ON IOL POWER CALCULATION AND ITS CO-RELATION WITH PTERYGIUM SIZE

Abstract Background: Pterygium is a common ocular surface disorder associated with ultraviolet exposure, with increased prevalence among individuals involved in outdoor activities and those residing in equatorial regions. The astigmatism induced by pterygium can distort keratometric measurements, thereby affecting the accuracy of intraocular lens (IOL) power calculation. Previous studies assessing changes in corneal curvature and IOL power after excision have reported variable results, with limited data from the Indian population. This study aims to evaluate the impact of pterygium excision on IOL power and examine its correlation with pterygium size through comparison of pre- and post-excision corneal parameters. Materials and Methods: This prospective interventional study included 40 patients with primary nasal pterygium (2–4 mm). Preoperative assessment included keratometry, axial length, corneal astigmatism, and IOL power calculation. All patients underwent pterygium excision with conjunctival limbal autograft. Postoperative evaluation was performed at 1 month. Changes in parameters were analysed using paired statistical tests, and correlation with pterygium size was assessed. Results: A total of 40 eyes of 40 patients (mean age 65.8 ± 9.6 years; range 40–80 years) were analyzed. Pterygium excision led to significant corneal steepening, with mean keratometry increasing from 44.70 ± 1.92 D to 45.35 ± 1.32 D (p = 0.03). Intraocular lens (IOL) power decreased from 22.20 ± 2.60 D to 21.00 ± 2.80 D (p = 0.02), while corneal astigmatism reduced from 2.45 ± 0.74 D to 2.10 ± 0.86 D (p = 0.02). Axial length remained unchanged (p = 0.23). A strong positive correlation was observed between pterygium size and magnitude of IOL power change, with larger lesions showing greater variability and reduction in IOL power. Conclusion: Pterygium significantly alters corneal curvature and influences IOL power calculation. The magnitude of change correlates with lesion size, supporting pterygium excision prior to cataract surgery for improved refractive accuracy.