Intraocular Lens Power and Corneal Topographic Change After Pterygium Surgery: Pterygium Effects on IOL Power Calculation.

ABSTRACT

PURPOSE: To investigate the impact of pterygium excision on intraocular lens (IOL) power calculation and corneal astigmatism. DESIGNS Prospective cohort study METHODS: We enrolled 30 eyes with primary pterygium that underwent pterygium excision with a conjunctival autograft. IOL power calculation and keratometry using the IOL Master 700, along with topographic parameters using the Pentacam Scheimpflug topography system, were performed preoperatively and at 1, 3, 6, and 12 months postoperatively. We analyzed correlations between pterygium length/area and IOL power, as well as corneal topographic changes. RESULTS: The mean pterygium length was 2.08 ± 0.58 mm, and the mean area was 6.05 ± 2.41 mm2. One year after pterygium surgery, the calculated IOL power values using all formulas were lower than the preoperative values. Pterygia with a horizontal length of 1.73 mm and an area of 4.45 mm2, and those with a horizontal length of 2.25 mm and an area of 6.95 mm2 created 0.5 D and 1.0 D errors in calculated IOL power, respectively (p<0.001). The calculated IOL power values changed significantly from preoperative to six months postoperatively but did not change significantly from six to 12 months postoperatively. Pterygia with a horizontal length greater than 1.83 mm (p<0.001) and an area greater than 5.1 mm2 (p < 0.001) created a 2.0 D error in anterior corneal astigmatism. CONCLUSIONS: Pterygium causes errors in IOL power calculation, with greater pterygium length/area exerting a larger effect. Cataract surgery with IOL implantation is recommended at least six months after pterygium surgery. In combined case, calculated IOL power should be decreased by 0.5-1.5 D based on the pterygium length/area.