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Topometrics characteristics of a population with keratoconus

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Session Details

Session Title: Special Cases

Session Date/Time: Sunday 14/09/2014 | 14:30-16:00

Paper Time: 14:54

Venue: Boulevard B

First Author: : F.Rodrigues PORTUGAL

Co Author(s): :    R. Almeida   A. Laura   I. Ramos   R. Correa   M. Salomão   R. Ambrosio

Abstract Details


To evaluate the topometrics characteristics of a population with clinical diagnosis of keratoconus, both eyes.


Renato Ambrósio Eye Institute (Rio de Janeiro, Brasil)


This retrospective study included 562 eyes of 281 patients with keratoconus, observed at the Renato Ambrósio Eye Institute (Rio de Janeiro). The diagnosis was based on the Collaborative Longitudinal Evaluation of Keratoconus Study (Clek). In addition to full ophthalmic examination, all patients underwent topography with Placido disc and corneal tomography with rotational scanning Scheimpflug (Oculus Pentacam® HR). The topometrics values of Pentacam, ie anterior derivatives of the cornea curvature were computed.


All cases in this series had the clinical diagnosis of keratoconus in both eyes. According to Krumeich-Amsler criteria, 19% had keratoconus grade 1, 8.7% keratoconus grade 1-2, 22.8% keratoconus grade 2, 13.9% keratoconus grade 2-3, 19.4% keratoconus grade 3, 11.9% keratoconus grade 3-4 and 1.9% keratoconus grade 4. The average pachymetry at the thinnest point was 452.64 µm ( +/- 60.18 µm) and 114 cases (20.3%) had values at thinnest point greater than 500 µm. 9.96 % had topometric pattern (TKC - topographic keratoconus classification) negative in the Oculus® system. The average age was 36.27 years (+/- 13.4). 169 (60 %) patients were men. The average central keratometry was 55.69D (+/- 8.81D) and 58 cases (10.32 %) had central keratometry lower than 47.4D. The average value of top/bottom asymmetry in 6mm (IS- value) was 6.23D (+/- 4.02D) and 41 cases (7.3%) had a IS- value lower than 1.4D. The average KISA index was 3434.51 (+/- 29214.76) and 74 cases (13.17%) had KISA index lower than 60%. The average IHD rate was 0.086 (+/- 0.0587) and 33 cases (5.87 %) were lower than 0.02.


There are cases of clinically diagnosed keratoconus who have relatively normal topometrics characteristics according to cut off values of current literature. These findings corroborate the concept of the need for a propedeutic approach including tomographic (paquimetric elevation and distribution) and biomechanic evaluation of the cornea for keratoconus.

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