A Novel Biomechanical Model To Diagnose Pediatric Keratoconus

Published 2023 - 41st Congress of the ESCRS

Reference: PP11.03 | DOI: 10.82333/w6fy-yx28

Authors: Jyoti H Matalia* ¹ , Himanshu Matalia ²

¹Pediatric Ophthalmology,Narayana Nethralaya,Bangalore,India, ²Anterior segment, Cornea and Refractive Surgery,Narayana Nethralaya,Bangalore,India

Keratoconus is confirmed based on the Pentacam HR map observation and clinical signs such as Fleischer ring, Vogt striae, scissoring of the red reflex etc. Keratoconus in children is known to be more aggressive than in adults. Hence highly sensitive markers are required to diagnose, stage and monitor the disease. This study focuses on presenting a novel corneal biomechanical marker for diagnosing keratoconus.

Narayana Nethralaya, Bangalore, India

42 normal and 41 keratoconic (KC) eyes of 83 subjects were analyzed in the study. All eyes underwent detailed clinical examination, along with Corvis-ST and Pentacam HR measurement. Corvis-ST recorded deformation data during the air-puff applanation of the eye was separated into corneal deformation and extra-corneal deformation. A model was developed using the waveform from Corvis-ST data which calculated constant (kc (constant)) and mean (kc (mean)) corneal stiffness representing the linear and nonlinear elastic response of the cornea to the applied force, extra-corneal stiffness (kg) and extra-corneal viscosity (µg) representing viscoelastic properties of the extra-corneal region.

Demographics parameters age (p=0.12) and IOP (p=0.32) was statistically similar between the groups. Pentacam HR parameters k1 (42.8 and 45.9 D), k2 (44.2 and 50 D), k max (44.6 and 55.5 D), central corneal thickness (537.5 and 453 µm) and thinnest corneal thickness (529.5 and 442 µm) was significantly different between the normal & KC group (p<0.001). Calculated kc (mean) was significantly different between the groups (p<0.001); 117.7 [112.5, 120.3] and 88.3 [84.5, 93.7] N/m respectively for normal and KC eyes respectively. Calculated kc (constant) was significantly different between the groups (p<0.001); 119.6 [114.3, 121.2] and 100.4 [97.6, 105.2] N/m respectively. Kg and µg was statistically similar between the groups.

Linear and non-linear stiffness calculated by the novel biomechanical model was able to capture the biomechanical degradation to the cornea due to keratoconus very well. Hence, they can be a valuable tool in diagnosing, staging and monitoring the disease.