Vector Analysis Of Astigmatism Correction After Treatment Of Coma In Patients Undergoing Laser Assisted In Situ Keratomileusis With Regular Corneal Optics

Coma has a significant influence on the astigmatic manifest refraction in coma-dominant irregular corneal optics, current evidence suggests coma does not impact astigmatism in regular corneal optics in a predictable fashion. Despite this evidence, concern regarding the accuracy of astigmatism correction in wavefront guided laser assisted in situ keratomileusis (LASIK) remains. The Schwind Amaris wavefront guided LASIK platform allows the customised treatment of specific higher order aberrations, such as the isolated treatment of coma. The purpose of this study was to review the accuracy of astigmatism correction in virgin eyes with regular corneal optics undergoing wavefront guided LASIK with the isolated treatment of coma.

A private, dedicated refractive clinic in Christchurch, New Zealand.

All eyes undergoing LASIK vision correction with regular corneal optics that demonstrated coma on wavefront aberrometry preoperatively from September 20222 to October 2024 were included in the analysis. On the Schwind ORK-CAM planning software, coma is determined as moderate if ranged between 0.25D and 0.5D, and significant if over 0.5D. All eyes demonstrating moderate and signifcant coma underwent wavefront guided LASIK with the isolated treatment of coma. Vector analysis was performed using the astigmatism double plot angle tool in alignment with current Journal of Cataract and Refractive Surgery guidelines.

A total of 100 eyes were included in the analysis. Isolated vertical coma was most prevalent on pre operative aberrometry. The mean pre operative RMS vertical coma was 0.06µm, the mean pre operative RMS horizontal coma was 0.05µm. The pre operative mean absolute keratometric astigmatism was 1.64D +/- 1.20D. The mean pre operative refractive astigmatism magnitude was 1.89D, ranging from 0 to 5.75D. The post operative refractive astigmatism prediction error centroid (difference vector) was 0.02 @ 74 degrees +/- 0.35D, with a mean absolute prediction error of 0.21D +/- 0.28D. A total of 92 eyes (92%) achieved a post operative residual refractive astigmatism of 0.5D.

Comparable astigmatism correction was achieved, suggesting the isolated treatment of coma in patients with regular corneal optics undergoing wavefront guided LASIK does not negatively impact the accuracy of astigmatism correction.