Localized Changes In Cone Characteristics And Biomechanical Properties In Progressive Keratoconus
Published 2025 - 43rd Congress of the ESCRS
Reference: FP03.03 | Type: Free paper | DOI: 10.82333/t4tm-4n33
Authors: Oliver Hassel* 1 , Lizaveta Chychko 1 , Lusine Vogormian 1 , Alexandra Negoescu 1 , Frederick Kremser 1 , Tadas Naujokaitis 1 , Grzegorz Łabuz 1 , Ramin Khoramnia 1 , Gerd Auffarth 1
1Ophthalmology,University Clinic Heidelberg,Heidelberg,Germany
Purpose
To evaluate regional changes in cone characteristics and biomechanical properties using novel custom-built programmes for each, in patients with progressive Keratoconus
Setting
Department of Cornea and Refractive Surgery, Medical Research Foundation, a tertiary eye care centre, Chennai, India
Methods
Keratoconic patients showing tomographic evidence of progression in at least one eye were included in this retrospective study.Patients with corneal surgery were excluded.Using tomographic data (Pentacam HR) and the Stress-Strain Index (SSI) from Corvis ST,custom built MATLAB codes and numerical modelling based on finite element simulation,were used to characterize the cone and to generate the SSI map. The cone characteristics and regional differences in SSI inside and outside the cone across the central 8mm of the corneal surface were documented. The changes in these parameters between the 2 visits across which progression of disease was noted were analysed statistically,using Wilcoxan Signed Rank test(p<0.05 was considered significant).
Results
Fifty eyes of 50 patients (78% male, mean age 19.1+7.3 years) with known keratoconus who showed tomographic evidence of progression (changes >95% confidence interval in any of the parameters in the ABCD classification system) were included. Mean interval for progression was 13.8+16.4 mths, during which Kmax increased by mean 2.3+2.8D(p=0.001), thinnest pachymetry reduced by mean 9.8+13.8µ(p=0.03). Cone height increased by mean 4+0.01µ, p=0.03). SSI was lower inside the cone than outside it in 100% of eyes. There was a greater reduction of SSI inside the cone(0.04+0.04µ, p=0.001) than outside the cone(0.02+0.05µ, p=0.03) when the disease progressed. The changes in area and location of the cone were not statistically significant.
Conclusions
This study endorses the view that Keratoconus represents a focal breakdown of biomechanical stability in the cone and that deterioration occurs more in the area of the cone than outside it as the disease progresses. This in vivo method of tracking localized changes in cone morphology and biomechanics could be clinically useful to detect early progression and pave the way for customized treatment protocols for progressive keratoconus