Corneal asymmetry in keratoconus: towards an eye asymmetry index

Session Details

Session Title: Presented Poster Session: Cornea – Medical

Session Date/Time: Saturday 05/09/2015 | 09:30-11:00

Paper Time: 09:50

Venue: Poster Village: Pod 4

First Author: : S.Linke GERMANY

Co Author(s): :    J. Steinberg   V. Druchkiv   G. Richard   T. Katz     

Abstract Details

Purpose:

To explore the intereye corneal asymmetry in normal and keratoconic individuals and to evaluate the discriminant power of single and combined asymmetry parameters.

Setting:

University based retrospcetive study.

Methods:

This is a retrospective designed study that included 672 patients who had Pentacam Scheimpflug topo- and tomographic imaging in both eyes: 267 subjects with bilateral normal corneas evaluated for refractive surgery and 405 with keratoconus. All elevation, pachymetric and volumetric based data (56 parameters) were electronically retrieved and analyzed. Intereye asymmetry was determined by subtracting the lowest value from the highest value for each variable. The degree of asymmetry between each subject's eyes was calculated with intraclass correlation coefficients. Receiver operating characteristic curve was used to determine predictive accuracy and to identify optimal cut-offs of these values and combinations thereof.

Results:

In the normal/ keratoconus subjects the mean intereye asymmetries were 0.36/ 5.04 for K2 (flat) meridian, 0.04/ 0.37 for BFS-front, 1.44/ 22.37 for Elevation Back BFS Apex, 8.01/ 40.77 for Pachy min. and 0.34/ 6.04 for RMS (cornea). High intraclass correlation (higher 0.8) between both eyes in normal subjects and reduced ICC (less 0.5) in keratoconus patients was observed for K Max Front, K2 (flat) meridian, Elevation Back BFS Apex, RMS (Cornea). Intereye asymmetry (normal versus keratoconus) for KISA, Z11 / Z31 (CF) and Z11 / Z31 (cornea) had an area under the receiver operating characteristic curve of 0.98.

Conclusions:

In addition to Rabinowitz`s Kmax intereye asymmetry, we propose pachymetric, elevation based and high order corneal wavefront intereye asymmetry parameters to improve the diagnostic armamentarium of keratoconus.

Financial Interest:

NONE