Posterior and total corneal astigmatism measured with optical coherence tomography–based biometer and dual Scheimpflug analyzer. Issue 12 (December 2020)

• Record Type: Journal Article
• Authors: Wang, Li; Cao, Danmin; Vilar, César; Koch, Douglas D.
• Is Part Of: Journal of cataract and refractive surgery. Volume 46:Issue 12(2020)
• Page Start: 1652
• Page End: 1658
• Publication Date: 2020-12
• Subjects: 617.7
• DOI: 10.1097/j.jcrs.0000000000000327
• Languages: English
• ISSNs: 0886-3350

Abstract

Abstract : Comparing total corneal astigmatism from 2 devices, 84.3% of eyes had differences in magnitude ≤0.50 D, and in eyes with astigmatism ≥0.5 D, 34.5% had differences in steep meridian ≤5 degrees. Abstract : Purpose: To compare corneal astigmatism obtained from an optical coherence tomography-based biometer (OCT) and dual Scheimpflug analyzer (DSA). Setting: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Design: Retrospective case series. Methods: Consecutive cases with both OCT and DSA measurements were reviewed. Three parameters were analyzed with OCT and DSA: (1) standard keratometric astigmatism (K vs simulated keratometry [SimK]), (2) posterior corneal astigmatism, and (3) total corneal astigmatism (total keratometry [TK] vs total corneal power [TCP]). The magnitudes of corneal astigmatism obtained from the 2 devices were compared. Vector analysis was used to assess differences in corneal astigmatism between devices. Results: In this study 530 corneas in 530 patients were measured. Compared with the DSA, the OCT produced a lower mean magnitude of posterior corneal astigmatism (−0.19 vs −0.29 diopter [D]) and a higher percentage of eyes with magnitude ≤0.25 D (75.5% vs 41.9%) ( P < .05). Comparing TK and TCP, (1) TK was greater in magnitudes (1.03 vs 0.98 D); (2) 84.3% of eyes had differences in magnitude of ≤0.50 D; (3) in eyes with TK astigmatism ≥0.5 D, 34.5% and 60.1% of eyes had differences in steep meridian of ≤5 degrees and ≤10 degrees, respectively, and (4) 59.2% of eyes had vector differences of ≤0.50 D. In with-the-rule and against-the-rule eyes, respectively, the vector differences between TK and TCP were 0.16 D @ 83 degrees and 0.17 D @ 12 degrees, and in posterior corneal astigmatism, 0.06 D @ 173 degrees; and 0.15 D @ 175 degrees. Conclusions: There were clinically significant differences in total corneal astigmatism obtained from OCT and DSA devices. Compared with DSA, OCT produced lower values for posterior corneal astigmatism.