The Prediction of Changes in Corneal Refractive Power Following Pterygium Surgery

1. Ja Young Lee
2. So Young Kim
3. Moon Sun Jung

Soonchunhyang University Cheonan Hospital, Cheonan, Korea

Purpose: To assess the relationship between size of pterygium and changes in corneal refractive power(K) following pterygium surgery and to predict changes in K. And to evaluate the time K was stabilized.

Methods: Thirty eight eyes were performed pterygium surgery using a conjunctival autograft. K was measured with autokeratometer(AR7100, Topcon, Japan) and corneal topography(Pentacam, Oculus, Germany) at preoperatively, 1 month and 3 months postoperatively. Parameters of pterygium size that include extension, width and area ratio were measured with image analysis at preoperatively and were analyzed a correlation with changes in K pre- and postoperatively. We drew the formula that could predict mean K following postoperatively with linear regression.

Results & Conclusions: Mean K measured at preoperatively, 1 month and 3 months postoperatively were as follows: with autokeratometer, 43.15±1.64D, 43.91±1.43D and 43.89±1.78D; with corneal topography, 42.59± 1.68D, 44.24±1.70D and 44.27±1.58D. The mean K measured with corneal topography significantly increased at 1 month and 3 months postoperatively (both p<0.01) but there was no significant difference between 1 month and 3 months postoperative. Area ratio was best correlated with changes of mean K(ΔK) among parameters of pterygium size that showed all positive correlation(linear regression, R2=0.49, p<0.01). We predicted changes in mean K using area ratio by formula "ΔK = 0.171 x Area ratio(%) – 0.402". Increasing mean K following pterygium surgery was stabilized after 1 month. Predicting of changes in mean K with area ratio of pterygium is useful in decision of intraocular lens power at performing cataract and pterygium surgery simultaneously.