Effects of Ocular Residual Astigmatism on Refractive Outcomes for Myopia Correction After Keratorefractive Lenticule...

To evaluate the effects of ocular residual astigmatism (ORA) on refractive outcomes for patients with astigmatism after keratorefractive lenticule extraction (KLEx) and to identify the ratio of the ORA/manifest refractive cylinder at the corneal plane (MRC) resulting in a greater index of success (IOS).

In total, 892 right eyes that underwent KLEx surgery were included. Astigmatic changes were evaluated using Alpins' vector analysis. Surgical outcomes grouped by ORA/MRC and ORA were compared. In stage 1, eyes were divided into two groups with an ORA/MRC cutoff value of 1. In stage 2, patients with an ORA/MRC ratio of greater than 1 were divided into two groups: those with an ORA of 1.25 diopters (D) or greater and those with an ORA of less than 0.50 D. ORA/MRC thresholds leading to a high IOS were analyzed using receiver operating characteristic (ROC) curves.

In stage 1, the mean IOS was 0.13 and 0.21 for the low and high ORA/MRC groups, respectively (P < .001). In stage 2, for high ORA/MRC, the IOS was significantly greater when the ORA was greater than 1.25 D than when the ORA was less than 0.50 D (0.27 versus 0.13, P < .001). ROC curves revealed that participants with an ORA/MRC ratio of greater than 1.8 were more likely to have a higher IOS (P < .001).

Patients with a smaller ORA can obtain better correction results. An ORA/MRC ratio of greater than 1.8 may increase the risk of poor astigmatism correction with KLEx. The application of vector planning may improve the refractive outcomes of KLEx. [J Refract Surg. 2024;40(12):e966-e973.].