Evaluation of corneal height data with the use of Scheimpflug topography according to different best fitting surfaces

Session Details

Session Title: Imaging Anterior Segment

Session Date/Time: Monday 07/09/2015 | 14:30-16:30

Paper Time: 15:54

Venue: Room 11

First Author: : M.Arvanitis GREECE

Co Author(s): :    R. Tsopouridou   D. Lioumi   A. Maniateas   V. Liarakos           

Abstract Details

Purpose:

To evaluate anticipated height data variation of corneal topography when assessed by 2 different surfaces: best fitting sphere (BFS) and best fitting toric ellipsoid (BFTE).

Setting:

“Eye Day Clinic”, Athens, Greece.

Methods:

We evaluated height data of 52 eyes with the use of Oculyzer (Wavelight) device, a Scheimpflug topography camera. Data were obtained for 9 central points for BFS and BFTE. Anterior and posterior surface astigmatism were also obtained at the same time. T-test, spearman correlation, linear regression and Wilcoxon test were used as appropriate.

Results:

Mean value of maximum height of anterior surface was 5.73 μm (± 3.15) and 1.73 μm (± 0.82) for BFS and BFTE respectively, with a statistically significant difference of 4 μm (p < 0.001). Height difference was significantly correlated with anterior surface astigmatism (p < 0.001). Mean value of maximum height of posterior surface was 11.83 μm (± 5.95) and 4.56 μm (± 1.91) for BFS and BFTE respectively, with a statistically significant difference of 7.27 μm (p < 0.001). Height difference was significantly correlated with posterior surface astigmatism (p < 0.001).

Conclusions:

Height data are of paramount importance in refractive surgery. The effect of best fitting surface demonstrates a significant impact in the calculation of height data both for anterior and posterior corneal surfaces, especially in corneas with astigmatism, but also for non astigmatic corneas to a lesser extent. BFTE better fits the true shape of cornea in presence of astigmatism. Even moderate height values in BFTE should be considered as suspicious.

Financial Interest:

NONE