Anterior, Posterior, and Non-Keratometric Contributions to Refractive Astigmatism in Pseudophakes
Purpose: To 1) investigate the relationship between measured anterior (ACA) and posterior (PCA) keratometric astigmatism and post-operative refractive astigmatism (RA) and 2) quantify non-corneal astigmatism (NCA) contributions to RA. Setting: Penn State College of Medicine, Hershey, PA. Design: Retrospective consecutive case series. Methods: Consecutive eyes underwent pre-operative biometry (IOLMaster 700) and tomography/topography using a dual-Scheimpflug placido disc-based device (Galilei G4), cataract surgery with implantation of a monofocal intraocular lens (IOL), and post-operative manifest refractions. RA was compared to keratometric astigmatism using the following methods: 1) IOLMaster, 2) SimK, 3) CorT, 4) SimK + measured PCA, 5) total corneal power at the corneal plane (TCP2), and 6) CorT(Total). An ocular residual astigmatism (ORA) vector was calculated between RA and each measured astigmatism. Results: Analysis was based on 296 eyes. ORA centroids were 0.28 @ 179, 0.45 @ 001, 0.37 @ 001, 0.19 @ 003, 0.19 @ 001, and 0.23 @ 178 D for the six afore-mentioned methods, respectively (P < .000001 [ORAx, ORAy]). Based upon TCP2 measurements, eyes with against-the-rule (ATR) ACA and with-the-rule (WTR) ACA had ORA centroids of 0.09 @ 082 and 0.58 @ 001 D (P < .000001 [ORAx, ORAy]), respectively. ORA was non-zero and not entirely explained by the cornea, especially in those with WTR ACA. Conclusions: Total keratometric astigmatism does not explain all ocular astigmatism. Non-corneal contributions are significant, especially in eyes with WTR ACA.
|Work Title||Anterior, Posterior, and Non-Keratometric Contributions to Refractive Astigmatism in Pseudophakes|
|License||CC BY-NC-ND 4.0 (Attribution-NonCommercial-NoDerivatives)|
|Publication Date||January 2021|
|Publisher Identifier (DOI)||
|Deposited||March 16, 2021|
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