The effect of pterygium surgery on intraocular lens power and ocular biometric parameters

To evaluate the effect of pterygium surgery on intraocular lens (IOL) power and ocular biometric parameters and to evaluate the factors affecting these parameters.

Twenty-eight eyes of 25 patients diagnosed with pterygium were evaluated. Axial length (AL), mean keratometry (Sim K), K1, K2, anterior chamber depth (ACD), corneal astigmatism, and ocular biometry parameters were obtained with a dual Scheimpflug analyzer. Pterygium sizes (horizontal, vertical) were measured manually, and pterygium height was analyzed with anterior segment optic coherence tomography. IOL power was calculated according to SRK/T, SRK II, Hoffer Q, Haigis, and Holladay formulas. Limbal conjunctival autograft was performed in all patients after excisional pterygium surgery. Preoperative and postoperative 1st month measurements were analyzed and compared.

The mean age of the patients was 51.5 ± 13.8 years. Mean horizontal pterygium length, vertical width, height, and percentage extension of the pterygium were 2.4 ± 0.9, 4.7 ± 1.0 mm, 297 ± 93µm, and 20.2 ± 7.2%, respectively. There was a significant increase in Sim K, K1, and K2 values postoperatively. Postoperative IOL power was significantly lower than preoperative values in all formulas. The change in IOL power after surgery was -0.3 ± 0.6D in the SRKT, -0.3 ± 0.5D in SRK II, -0.4 ± 0.7D in Hoffer Q, -0.5±0.7D in Haigis, and -0.3 ± 0.7D in Holladay 2 formulas. The change in IOL power has a moderate positive linear correlation with the horizontal and vertical sizes of the pterygium and a high positive linear correlation with the percentage extension of the pterygium.

Pterygium surgery causes a significant decrease in calculated IOL power obtained with all formulas. It becomes more pronounced with the increase in the size of the pterygium.