Abnormal Corvis Biomechanical Indices In Pediatric Hyperopia: Keratoconus Or Age-Related Elasticity?

To determine whether elevated Corvis ST biomechanical indices in pediatric hyperopic eyes represent early keratoconus or reflect normal age-related corneal elasticity.

Advanced Eye Care Hospital, Beirut, Lebanon.

A retrospective cross-sectional study included 139 pediatric patients (277 eyes) aged 0–17 years with hyperopic or emmetropic refraction who underwent Corvis ST assessment. Myopic eyes and known corneal pathology were excluded. Abnormal biomechanical indices were defined using adult thresholds: Corvis Biomechanical Index (CBI) ≥0.50 and Tomographic Biomechanical Index (TBI) ≥0.79 (≥0.29 suspicious). Proportions exceeding thresholds were calculated and correlated with clinical and tomographic findings of keratoconus.

Using adult thresholds, 45% of eyes demonstrated CBI ≥0.50 and 22% exceeded CBI ≥0.90. Among eyes with tomographic integration (n=39), 33% showed TBI ≥0.79 and 85% exceeded 0.29. Despite these high rates of “abnormal” biomechanical indices, no eyes demonstrated clinical or tomographic evidence of keratoconus except one outlier with marked corneal thinning. The majority of elevated indices therefore represented false positives. Hyperopic pediatric corneas, expected to be biomechanically stronger than myopic eyes, nonetheless frequently exceeded adult ectasia thresholds, suggesting age-related corneal elasticity as the primary driver.

Adult Corvis ST cutoff values identify a large proportion of normal pediatric hyperopic corneas as abnormal, indicating high false-positive rates for keratoconus in children. Elevated biomechanical indices in pediatric hyperopia likely reflect physiologic corneal elasticity rather than ectatic disease. Pediatric-specific normative values or age-adjusted thresholds are required to improve diagnostic accuracy and prevent overdiagnosis.