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Astigmatic axis repeatability in normal, keratoconic, collagen cross-linked and LASIK-treated eyes with novel multi-colored spot reflection topography

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Session Details

Session Title: Presented Poster Session 11: Refractive Surgery New Techniques / Instrumentation / Devices 1

Session Date/Time: Sunday 14/09/2014 | 15:00-17:00

Paper Time: 15:30

Venue: Pod 2 (Poster Village)

First Author: : G.Pamel GREECE

Co Author(s): :    A. Kanellopoulos   G. Asimellis           

Abstract Details


To evaluate the clinical efficacy of a novel corneal topography device and investigate repeatability of steep and flat keratometry measurements as well as astigmatism axis in normal, keratoconic, cross-linked, and LASIK-treated eyes.

Setting: Eye Institute, Athens, Greece


Steep and flat keratometry and astigmatism axis measurement repeatability was investigated via a novel multicolored-spot reflection topographer (Cassini) in a group of control patients (group-A), and three study groups, namely a myopic LASIK-treated group-B, a keratoconic group-C, and a cross-linked group-D.


Flat keratometry repeatability was 0.74±0.89 (0.03 to 5.26) D in the LASIK group-A, 0.88±1.45 (0.00 to 7.84) D in the keratoconic group-B, and 0.71±0.94 (0.02 to 6.23) D in the Athens Protocol group-C. The control group-D had flat keratometry repeatability 0.36±0.46 (0.00 to 2.71) D. Steep keratometry repeatability was 0.64±0.82 (0.01 to 4.81) D in the LASIK group-A, 0.89±1.22 (0.02 to 7.85) D in the keratoconic group-B, and 0.93±1.12 (0.04 to 5.93) D in the Athens Protocol group-C. The control group-D had steep keratometry repeatability 0.41±0.50 (0.00 to 3.51) D. Axis repeatability was 3.45±1.62 (0.38 to 7.78)° for the LASIK group-A, 4.12±3.17 (0.02 to 12.13)° for the keratoconic group-B, and 3.20±1.99 (0.17 to 8.61)° for the Athens Protocol group-C. The control group-D had axis repeatability 2.16±1.39 (0.05 to 5.86)°.


This novel corneal topography device appears to offer very high specificity in estimating astigmatism and corneal keratometry and specific corneal irregularity indices even in topographically challenging corneas such as LASIK-treated, keratoconic, and cross-linked. The system identified astigmatism shift from on average ‘with-the-rule’ to ‘against-the-rule’ with aging. Employment of this novel multi-colored spot reflection topography results in astigmatism magnitude repeatability under 0.6D and axis repeatability under 3°.

Financial Interest:

One or more of the authors... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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