Institutional members access full text with Ovid®

Share this article on:

Correlation of the Corneal Toricity Between Anterior and Posterior Corneal Surfaces in the Normal Human Eye

Montalbán, Raúl MSc; Piñero, David P. PhD; Javaloy, Jaime MD, PhD; Alio, Jorge L. MD, PhD

doi: 10.1097/ICO.0b013e31827bf898
Clinical Science

Purpose: To evaluate the correlation of the magnitude of corneal toricity and power vector components of both corneal surfaces measured with a Scheimpflug photography-based system.

Methods: A total of 117 healthy normal eyes of 117 subjects selected randomly with ages ranging from 7 to 80 years were included. All eyes received an anterior segment and corneal analysis with the Sirius system (CSO) evaluating the anterior and posterior mean toricity for 3 and 7 mm (aAST and pAST). The vector components J0 and J45 as well as the overall strength blur (B) were calculated for each keratometric measurement using the procedure defined by Thibos and Horner.

Results: The coefficient of correlation between aAST and pAST was 0.52 and 0.62 and the mean anteroposterior ratio for toricity was 0.46 ± 0.39 and 0.57 ± 0.75 for 3 and 7 mm, respectively. These ratios correlated significantly with aAST, anterior corneal J0, and manifest refraction J0 (r ≥ 0.39, P < 0.01). The coefficient of correlation was 0.69 and 0.81 between anterior and posterior J0 for 3 and 7 mm, respectively. For J45, the coefficients were 0.62 and 0.71, respectively. The linear regression analysis revealed that the pAST and power vectors could be predicted from the anterior corneal data (R2 ≥ 0.40, P < 0.01).

Conclusions: The toricity and astigmatic power vector components of the posterior corneal surface in the human healthy eye are related to those of the anterior and therefore can be predicted consistently from the anterior toricity and astigmatic power vectors.

*Instituto Oftalmológico de Alicante, Vissum Corporation, Alicante, Spain

Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Alicante, Spain

Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.

Reprints: David P. Piñero, Departamento de Óptica, Farmacología y Anatomía. Universidad de Alicante, Spain, Carretera San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Alicante, Spain (e-mail:

The authors have no funding or conflicts of interest to disclose.

Received July 01, 2012

Accepted October 30, 2012

Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.