Estimation of scleral mechanical properties from air-puff optical coherence tomography

Abstract

We introduce a method to estimate the biomechanical properties of the porcine sclera in intact eye globes ex vivo, using optical coherence tomography that is coupled with an air-puff excitation source, and inverse optimization techniques based on finite element modeling. Air-puff induced tissue deformation was determined at seven different locations on the ocular globe, and the maximum apex deformation, the deformation velocity, and the arc-length during deformation were quantified. In the sclera, the experimental maximum deformation amplitude and the corresponding arc length were dependent on the location of air-puff excitation. The normalized temporal deformation profile of the sclera was distinct from that in the cornea, but similar in all tested scleral locations, suggesting that this profile is independent of variations in scleral thickness. Inverse optimization techniques showed that the estimated scleral elastic modulus ranged from 1.84 ± 0.30 MPa (equatorial inferior) to 6.04 ± 2.11 MPa (equatorial temporal). The use of scleral air-puff imaging holds promise for non-invasively investigating the structural changes in the sclera associated with myopia and glaucoma, and for monitoring potential modulation of scleral stiffness in disease or treatment.

Assessment of corneal biomechanics in anisometropia using Scheimpflug technology

“…But the corneal biomechanical asymmetry between anisometropic eyes may be limited by the same genetic background. Thirdly, even though cornea and scleral are a whole, their biomechanical behaviors are still different when stress is applied ( Bronte-Ciriza et al, 2021 ), thus corneal biomechanical measures may not fully represent the scleral biomechanics.…”

Effects of Different Scleral Photo-Crosslinking Modalities on Scleral Stiffness and Hydration

“… 49 Whereas the intact eye in inflation tests more closely approximates physiological conditions, the scleral properties reconstructed from inflation tests are necessarily influenced by assumptions regarding the cornea 51 , 52 and ocular tissues as well as the preconditioning response during inflation. 50 Conversely, the tensile test provides us with a direct quantification of the YM of tissues that other techniques can only obtain through inverse viscoelastic reconstruction techniques from air-puff deformation 23 , 24 , 53 or OCE measurements. 40 , 42 In addition, some studies have identified a preferential orientation of scleral collagen fibers.…”

Scleral anisotropy in ex vivo rabbit eyes using ultrasonic optical coherence elastography

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