Enhancing the diagnostic precision of subclinical keratoconus by combining indices from Scheimpflug tomography, corneal biomechanics, and anterior segment optical coherence tomography

To determine the diagnostic precision of combined Scheimpflug tomography and biomechanical analysis with optical coherence tomography (OCT) for detection of subclinical keratoconus (SCKC).

All subjects in this prospective, cross-sectional study underwent Scheimpflug tomography (Pentacam HR), air-puff tonometry (Corvis ST), and spectral-domain optical coherence tomography (Cirrus HD SD-OCT). The diagnosis of SCKC and keratoconus (KCN) were based on the Oculus Pentacam classification. Combined diagnostic models were developed using stepwise logistic regression (SLR). The Kruskal-Walli’s test evaluated group differences. Diagnostic accuracy was assessed by calculating the area under the curve (AUC).

A total of 137 participants comprising 73 females and 64 males, including 48 with KCN, 36 with SCKC, and 53 with normal corneas. The mean age for each group was 31.39±10.82y, 29.25±7.33y, and 30.45±8.03y, respectively. Most examined tomography, biomechanical, and pachymetry indices showed significant differences between KCN, SCKC, and normal eyes (P<0.05). Single tomographic biomechanical index (TBI) data was the most effective in identifying SCKC, achieving an AUC of 0.978 (P<0.001) with 100% sensitivity and 84.91% specificity. Combining SD-OCT and Pentacam HR data, the SLR model yielded superior accuracy for SCKC detection, with an AUC of 0.966 (86.11% sensitivity and 96.13% specificity). The highest accuracy for SCKC identification was attained by integrating data from all three devices, resulting in 0.990 accuracy (91.67% sensitivity; 100% specificity).

While current parameters accurately identify KCN, they are less effective for SCKC. Integrating Scheimpflug-based biomechanical and tomographic analysis with SD-OCT improves SCKC detection, supporting more accurate screening and earlier identification in patients with otherwise normal findings.