The Role Of Baseline Corvis St Corneal Biomechanics For Early Keratoconus Progression: Tomographic Severity- Adjusted Biomechanical Assessment

Published 2026 - 44th Congress of the ESCRS

Reference: FP06.11 | Type: Free paper | DOI: 10.82333/6bwe-be22

Authors: Dr Kubra Gul Olke* ¹ , Dr Beste Gizem Kose ² , Dr Ahmet Yigiter ² , A/Prof. Betul Seher Uysal ² , Prof. Dr Mehmet Cuneyt Ozmen ² , Prof. Dr Kamil Bilgihan ²

¹Department of Ophthalmology,Gazi University, Faculty of Medicine,Ankara,Türkiye;Department of Ophthalmology,Adana City Training and Research Hospital,Adana,Türkiye, ²Department of Ophthalmology,Gazi University, Faculty of Medicine,Ankara,Türkiye

Purpose

This study aimed to identify baseline corneal tomographic (Pentacam HR) and biomechanical (Corvis ST) predictors of 6-month keratoconus (KC) progression, while minimizing confounding by age, sex, and disease severity (BAD-D) through inverse probability of treatment weighting (IPTW), and to quantify the discriminatory performance of key biomechanical metrics.

Setting

Single-center retrospective cohort at a tertiary referral cornea clinic.

Methods

Consecutive KC patients presenting for initial evaluation (Jan 2018–Dec 2023) were screened. Eyes with prior corneal surgery, contact lens wear within 4 weeks, concurrent ocular pathology, or incomplete Pentacam/Corvis data were excluded; only Corvis scans graded “OK” were analyzed. KC was diagnosed per the Global Consensus. Patients more than 18 years old with ≥ 6-month follow-up and baseline Pentacam and Corvis ST were included. Progression at 6 months (progressive- KC; p-KC) was defined by any one of: ≥1.0 D Kmax increase, ≥0.75 D astigmatism increase, ≥30 µm CCT decrease, or ≥1-line VA loss. Confounding by age, sex, and BAD-D was addressed with stabilized IPTW (|SMD|<0.10). Groups were compared using IPTW-weighted regression and ROC.

Results

Ninety-one eyes (p-KC n=47, non progressive- KC n=44) were analyzed. IPTW balanced age, sex, and BAD-D (|SMD|<0.07; p>0.82). After IPTW, Maxinverse Radius was higher (WMD +19.96, 95% CI 2.74–37.18; p=0.023) and Radius mm lower (WMD −0.41; 95% CI −0.81 to −0.006; p=0.047) in p-KC eyes; SP-A1 trended lower (p=0.067). CBI was higher in p- KC eyes (WMD +0.042; 95% CI 0.005–0.080; p=0.026). Maxinverse Radius predicted progression (OR 2.15 per 1 SD, 95% CI 1.10–4.22; p=0.026). The Maxinverse Radius+ SP-A1 model had the numerically highest AUC (0.646; sensitivity 77.7%, specificity 50.5%); Maxinverse Radius remained significant in the multivariable model (OR 1.75, 95% CI 1.04–2.95; p=0.034), whereas SP-A1 was not (p=0.153).

Conclusions

Baseline corneal biomechanics showed modest ability to discriminate keratoconus progression in tomographically comparable groups. Progressive KC exhibited higher Maxinverse Radius and CBI and lower Radius mm, while SP-A1 showed a borderline trend. These findings suggest that biomechanical assessment at initial examination may provide additional information beyond standard tomography for short-term risk stratification.