Corneal stress factor as a predictor of keratoconus progression

Session Details

Session Title: Corneal Biomechanics

Session Date/Time: Monday 09/10/2017 | 08:00-10:30

Paper Time: 08:56

Venue: Room 2.1

First Author: : H.Ginis GREECE

Co Author(s): :    P. Koutsogiannakopoulou   C. Katsoulos   M. Chantzou   P. Zafirakis   G. Rallatos        

Abstract Details

Purpose:

Corneal Stress Factor (CSF) is a new parameter characterising the mechanical stress on the cornea associated to the load from intraocular pressure. CSF is inspired by thin wall pressure vessel theory and is calculated based on corneal shape (elevation, thickness). The CSF is calculated as a map that indicates the stress distribution across the cornea. The purpose of this study was to evaluate the sensitivity and specificity of this new parameter for the prediction of keratoconus progression.

Setting:

Athens Eye Hospital, Athens Greece and University of Crete, Heraklion, Greece.

Methods:

We evaluated retrospectively topographic data from 36 eyes of 36 patients diagnosed with keratoconus at the Athens Eye Hospital (left/right eye selected randomly). Follow up ranged from six (6) to forty (40) months. Patients who underwent corneal cross linking were not included for analysis. CSF maps were calculated for each examination. Keratoconus progression was evaluated by means of changes in the keratometric power (K1,K2), anterior chamber depth (ACD), central pachymetry (P) and anterior chamber volume (V). As a study parameter we calculated the average CSF in a central zone of the cornea having a diameter of 6 mm.

Results:

Seven eyes (out of 36) showed keratoconus progression manifested as an increase of corneal power (mean of K1 and K2) higher than 2 D or increase of stigmatism higher than 1D. The progression was consistent with an overall steepening of the central cornea and deterioration its topographic appearance. All progressing cases had SCF higher than 1280 kPa/mmHg at the first examination and continued to progress if SCF was higher than this threshold in the following visits. An age matched group of non-progressing keratoconus had CSF lower than 1280kPa/mmHg at all visits.

Conclusions:

CSF quantifies the mechanical stress on the cornea, presumably a causative factor of ectatic deformation. In our data, elevated SCF was associated to keratoconus progression in all cases. Moreover, no eye with elevated SCF remained stable. It is suggested that CSF may be a sensitive and specific predictor of keratoconus progression.

Financial Disclosure:

NONE