Timing optimization for primary pterygium excision with conjunctival-limbal autograft to restore the corneal optical properties

Abstract

Purpose: To propose the optimal value of baseline corneal astigmatism and pterygial morphological profiles for primary pterygium surgery to restore the corneal optical properties. Methods: We analysed 93 eyes from 84 subjects with nasal-only primary pterygium who underwent pterygium excision with conjunctival-limbal autograft and were assessed perioperatively using anterior segment swept-source optical coherence tomography (AS SS-OCT). We collected data on anterior corneal astigmatism (ACA) and root mean square (RMS) values for anterior corneal lower- (LoA) and higher-order aberrations (HoA) as corneal optical properties using AS SS-OCT. Using preoperative ACA and four pterygial morphological profiles (horizontal invasion length [HIL], height, thickness and the ratio of residual corneal thickness [RCT] to central corneal thickness [CCT]) measured in AS SS-OCT, we plotted receiver operating characteristic (ROC) curves. These curves aimed to determine cut-off values predicting a perioperative decrease exceeding 50% in ACA, RMS LoA and RMS HoA, as well as postoperative residual ACA higher than 1.25D. Results: Preoperative ACA > 1.42D (AUC = 0.934) and >3.60D (AUC = 0.946) proved most effective in identifying subjects with perioperative decrease exceeding in ACA and RMS LoA, respectively. HIL > 3.34 mm (AUC = 0.941) was most effective in distinguishing subjects with perioperative reduction exceeding 50% in RMS HoA. Preoperative ACA > 5.78D (AUC = 0.776) and HIL > 5.03 mm (AUC = 0.700) significantly distinguished subjects with postoperative residual ACA higher than 1.25D. Conclusion: Optimizing the restoration of corneal astigmatism and aberrations after pterygium surgery may be facilitated by determining the optimal surgical timing based on preoperative ACA and HIL values.