Assessment of central and peripheral corneal astigmatism in an elderly population: a retrospective analysis of topography results from 717 eyes
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First Author: G.Labuz GERMANY
Co Author(s): D. Varadi R. Khoramnia G. Auffarth
Corneal astigmatism can be successfully corrected with implantation of a toric intraocular lens (IOL), which has become a standard in modern cataract surgery. The selection of lens power is based on astigmatism measurements taken in the central (about 3mm) cornea. In this study, we aimed to evaluate how astigmatism in an elderly population changes from the center to the corneal periphery.
David J Apple Center for Vision Research, Department of Ophthalmology, University of Heidelberg, Germany.
We retrospectively analyzed Pentacam Scheimpflug corneal topography data obtained between October 2004 and June 2019 during routine patient examinations at the Heidelberg University Eye Clinic. The total corneal astigmatism (i.e., from the anterior and posterior surface) was obtained and compared for 3- and 6-mm concentric areas. We included only patients who were 60 years of age or older at the time of examination who had at least 1D of astigmatism. We randomly chose one eye per subject in a total selection of 717 eyes used for statistical analysis.
The mean corneal astigmatism in the center was 1.82 ±0.88D, and at the periphery, it was 1.64 ±0.98D, which was statistically significant (paired t-test, P=.001). However, this difference increased with the cylinder power, as for cases with low astigmatism (up to 2.0D) it was 0.13 ±0.37D, 0.27 ±0.57D in the range 2.0 to 3.0D, 0.34 ±0.57D in the range 3.0 to 4.0D, and 0.59 ±0.70D for astigmatism greater than 4.0D. The mean difference in the axis of astigmatism between the 3mm and 6mm zone was 0.1º ± 29.1º (paired t-test, P = .90).
We demonstrated that central corneal astigmatism differs from that measured at the periphery and that a larger difference was found in patients with higher astigmatism. Our findings suggest that toric IOLs can be improved by decreasing the cylinder power at the lens’ periphery to more accurately correct corneal astigmatism.
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