Preoperative pterygium extension rate predicts postoperative corneal optical recovery after pterygium excision

Pterygium progression induces corneal optical distortion, and delayed surgery may limit postoperative recovery of corneal optics. However, quantitative criteria indicating the latest acceptable timing of surgery remain unclear. This study aimed to determine extension-rate thresholds predicting postoperative normalization of corneal asymmetry and higher-order irregularity (HOI).

This retrospective observational study included 134 eyes with primary pterygium that underwent surgical excision. The pterygium extension rate was calculated from slit-lamp photographs as the ratio of the apex-to-limbus distance to the horizontal corneal diameter. Corneal asymmetry and HOI within the central 3-mm zone were measured preoperatively and 1 month postoperatively using swept-source anterior segment optical coherence tomography. Receiver operating characteristic (ROC) analyses were used to determine cutoff values predicting postoperative normalization.

The pterygium extension rate correlated significantly with preoperative corneal asymmetry (r = 0.5899, p < 0.001) and HOI (r = 0.5462, p < 0.001). ROC analysis showed good predictive ability for postoperative corneal asymmetry (AUC 0.80; cutoff 0.359; sensitivity 58.0%, specificity 89.3%) and moderate predictive ability for HOI (AUC 0.74; cutoff 0.292; sensitivity 72.3%, specificity 64.7%). Postoperative normalization occurred in 62.7% of eyes for asymmetry and 38.1% for HOI.

The pterygium extension rate is a simple clinical metric that predicts postoperative optical recovery. These extension-rate thresholds may help support clinical estimation of how long pterygium surgery may be deferred while maintaining the possibility of postoperative optical recovery.