Astigmatism-type-specific impact of peripheral corneal thickness on anterior keratometric profile changes after temporal clear corneal incision cataract surgery.

Postoperative astigmatism remains a concern after temporal clear corneal incision (TCCI) cataract surgery, especially in eyes with preexisting corneal astigmatism. This study investigated whether peripheral-to-central corneal thickness ratios can predict anterior corneal astigmatic shifts following surgery and whether these associations vary by preoperative anterior corneal astigmatism type. We retrospectively, analyzed 209 eyes from 137 patients who underwent uneventful phacoemulsification with 2.75 mm TCCI and intraocular lens implantation. Preoperative central corneal thickness (CCT), mid-peripheral corneal thicknesses (MPCT, 5-7 mm), and temporal peripheral corneal thickness (TPCT, 7-10 mm) were measured using anterior segment optical coherence tomography (Visante; Carl Zeiss Meditec, Germany). Patients were categorized into with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism groups based on their preoperative anterior corneal astigmatism. In the WTR group, higher TPCT/CCT and MPCT/CCT ratios showed significant correlations with an increase in postoperative anterior corneal astigmatism (r = 0.293, P = 0.011; r = 0.301, P = 0.009). In the oblique group, MPCT/CCT was correlated with changes in flat, steep, and average anterior keratometry. No significant correlations were observed in the ATR group. Receiver operating characteristic analysis identified TPCT/CCT ≥ 1.118 and MPCT/CCT ≥ 1.046 as thresholds for predicting a ≥  + 0.25 diopter increase in postoperative anterior corneal astigmatism in WTR eyes, demonstrating sensitivities of 95.0% and 87.5% and specificities of 34.3% and 45.7%, respectively. These findings suggest that peripheral-to-central corneal thickness ratios may serve as useful predictors of surgically induced anterior corneal astigmatism in patients with WTR astigmatism and can inform preoperative assessment and surgical planning.