Journal ArticleDOI
Contribution of posterior corneal astigmatism to total corneal astigmatism.
Douglas D. Koch,Shazia F. Ali,Mitchell P. Weikert,Mariko Shirayama,Richard B. Jenkins,Li Wang +5 more
TLDR
Selecting toric intraocular lenses based on anterior corneal measurements could lead to overcor correction in eyes that have with‐the‐rule astigmatism and undercorrection in eyes which have against‐the-ruleAstigmatism.Abstract:
Purpose To determine the contribution of posterior corneal astigmatism to total corneal astigmatism and the error in estimating total corneal astigmatism from anterior corneal measurements only using a dual-Scheimpflug analyzer. Setting Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Design Case series. Methods Total corneal astigmatism was calculated using ray tracing, corneal astigmatism from simulated keratometry, anterior corneal astigmatism, and posterior corneal astigmatism, and the changes with age were analyzed. Vector analysis was used to assess the error produced by estimating total corneal astigmatism from anterior corneal measurements only. Results The study analyzed 715 corneas of 435 consecutive patients. The mean magnitude of posterior corneal astigmatism was −0.30 diopter (D). The steep corneal meridian was aligned vertically (60 to 120 degrees) in 51.9% of eyes for the anterior surface and in 86.6% for the posterior surface. With increasing age, the steep anterior corneal meridian tended to change from vertical to horizontal, while the steep posterior corneal meridian did not change. The magnitudes of anterior and posterior corneal astigmatism were correlated when the steeper anterior meridian was aligned vertically but not when it was aligned horizontally. Anterior corneal measurements underestimated total corneal astigmatism by 0.22 @ 180 and exceeded 0.50 D in 5% of eyes. Conclusions Ignoring posterior corneal astigmatism may yield incorrect estimation of total corneal astigmatism. Selecting toric intraocular lenses based on anterior corneal measurements could lead to overcorrection in eyes that have with-the-rule astigmatism and undercorrection in eyes that have against-the-rule astigmatism. Financial Disclosure The authors received research support from Ziemer Group. In addition, Dr. Koch has a financial interest with Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Calhoun Vision, Inc., NuLens, and Optimedica Corp.read more
Citations
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Journal ArticleDOI
Correcting astigmatism with toric intraocular lenses: Effect of posterior corneal astigmatism
TL;DR: Corneal astigmatism was overestimated in WTR by all devices and underestimated in ATR by all except the Placido–dual Scheimpflug analyzer.
Journal ArticleDOI
Cataract in the Adult Eye Preferred Practice Pattern
Randall J. Olson,Rosa Braga-Mele,Sherleen H. Chen,Kevin M. Miller,Roberto Pineda,James P. Tweeten,David C. Musch +6 more
Journal ArticleDOI
Multifocal intraocular lenses: Relative indications and contraindications for implantation
Rosa Braga-Mele,David F. Chang,Steven H. Dewey,Gary Foster,Bonnie An Henderson,Warren Hill,Richard S. Hoffman,Brian Little,Nick Mamalis,Thomas A. Oetting,Donald Serafano,Audrey Talley-Rostov,Abhay R. Vasavada,Sonia H. Yoo +13 more
TL;DR: An extensive overview of best clinical practice pertaining to selection and use of multifocal intraocular lenses currently available in the United States is presented.
Journal ArticleDOI
Assessing progression of keratoconus: novel tomographic determinants
TL;DR: How modern corneal tomography, including both anterior and posterior elevation and pachymetric data can be used to screen for ectatic progression, and how software programs such as the Enhanced Reference Surface and the Belin-Ambrosio Enhanced Ectasia Display can be employed to detect earlier changes are described.
Journal ArticleDOI
An analysis of the factors influencing the residual refractive astigmatism after cataract surgery with toric intraocular lenses.
Giacomo Savini,Kristian Næser +1 more
TL;DR: Posterior corneal astigmatism exerts the highest influence on the ERA after toric IOL implantation, and basing calculations on total cornealeastigmatism rather than keratometricAstigmatic data were vectorially described by meridional and torsional powers, which improves the prediction of the residual refractiveAstigmatism.
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Journal ArticleDOI
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