Corneal biomechanical weakening presumably precedes keratoconus (KC), an ocular disease that leads to vision loss. Cross-meridian swept-source OCT coupled to air-puff excitation was used to induce corneal deformation to investigate biomechanics in Forme Fruste (FF)/subclinical (n=10), KC I (n=10) and healthy (n=12) eyes. Shape and asymmetry deformation parameters were analyzed in two meridians, and the tangent modulus was calculated using Finite Element modeling (FEM). Compared to healthy eyes, the asymmetry parameter decreased 0.32±0.05% (FF/subclinical), and 0.66±0.18% (KC I). The shape parameter increased 0.91±0.32% (FF/subclinical) and 1.47±1.2% (KC I). Significant differences between groups were observed mostly on the vertical meridian. Inverse FEM showed ∼30% localized stiffness reduction in KC eyes, compared to healthy eyes. Our results show that the additional vertical meridian allows more significant use of deformation parameters as biomarkers of biomechanical changes.
Quantification of the corneas´ biomechanical properties helps to diagnose corneal abnormalities early, which is key in keratoconus (KC) management and treatment. We recently introduced a multi-meridian air-puff ssOCT system capable of acquiring corneal deformation images during air-puff excitation on two meridians. Two healthy and three KC patients were measured with the system. The results were used to quantify deformation asymmetries and as input data for Finite Element (FE) modeling, which was used to estimate corneal biomechanical properties by means of an inverse analysis. Deformation asymmetry parameters and the estimated tangent modulus for healthy and KC corneas are presented and compared.
We are introducing a proof-of concept method to estimate scleral mechanical properties from air-puff deformation imaging using optical coherence tomography (OCT), customized surface segmentation methods, and 3D finite element analysis on porcine eyes.
Air-puff induced corneal deformation imaging reveals information highlighting normal and pathological corneal response to a non-contact mechanical excitation. Here, we present a novel customized swept-source optical coherence tomography system coupled with a collinear air-puff excitation. We acquired unobstructed dynamic corneal deformation on multiple meridians with two custom scan patterns over a field of view of up to 15 mm x 15 mm and selected puff profiles at unprecedented scan rates, both ex vivo and in vivo. We show that our system can detect corneal deformation profiles and deformation asymmetries that are useful for corneal biomechanics diagnostics and pathology screening.
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