Impact of pterygium excision on intraocular lens power and corneal astigmatism: A prospective clinical analysis
K. R. Vaisakh, K. H. Srinivasa, Bharathi Nimmanapalli, Rupali BhatABSTRACT
Purpose:
To quantitatively evaluate the changes in anterior corneal astigmatism and predicted intraocular lens (IOL) power following primary nasal pterygium excision with conjunctival autograft, and to determine the correlation between preoperative pterygium size and these refractive shifts to optimize surgical sequencing in patients with coexisting cataract.
Methods:
This prospective, interventional cohort study was conducted at a tertiary care ophthalmic institute. Thirty eyes of 30 patients with primary nasal pterygium encroaching ≥ 2 mm onto the cornea were enrolled. All participants underwent pterygium excision with limbal-conjunctival autograft secured with 10-0 nylon sutures. Comprehensive biometry was performed preoperatively and at one month postoperatively using the IOL Master 700 (swept-source OCT). Key outcome measures included changes in keratometry (K1, K2), anterior corneal astigmatism, and IOL power calculated using the SRK/T formula.
Results:
The study cohort had a mean pterygium horizontal extension of 4.1 ± 1.6 mm. Postoperative analysis at one month revealed statistically significant corneal steepening. Mean preoperative anterior corneal astigmatism reduced from 5.05 ± 3.90 D to 1.58 ± 2.27 D (P < 0.001). Consequently, the mean predicted IOL power decreased significantly from a preoperative value of 22.64 ± 5.40 D to 21.51 ± 3.20 D postoperatively, representing a mean hyperopic shift of 1.12 D (P = 0.00017). A strong positive correlation was identified between preoperative pterygium size and the magnitude of astigmatic reduction (Pearson’s r ≈ 0.93).
Conclusion:
Pterygium excision induces significant corneal steepening and reduction of localized astigmatism, resulting in a clinically relevant decrease in required IOL power. To minimize the risk of refractive surprises, sequential surgery may be considered for pterygia encroaching >2 mm onto the cornea.