Posterior and total corneal astigmatism measured with optical coherence tomography-based biometer and dual Scheimpflug analyzer.

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.

• Authors: Li Wang, Danmin Cao, César Vilar, Douglas D Koch
• Journal: Journal of cataract and refractive surgery (J Cataract Refract Surg) Vol. 46 Issue 12 Pg. 1652-1658 (Dec 2020) ISSN: 1873-4502 [Electronic] United States
• PMID: 32842077 (Publication Type: Journal Article)

Topics

• Astigmatism (diagnosis)
• Cornea (diagnostic imaging)
• Corneal Topography
• Humans
• Retrospective Studies
• Tomography, Optical Coherence