A Method to Estimate Biomechanics and Mechanical Properties of Optic Nerve Head Tissues From Parameters Measurable Using Optical Coherence Tomography

• Published in: IEEE transactions on medical imaging 2014-06, Vol.33 (6), p.1381-1389
• Main Authors: Sigal, I. A., Grimm, J. L., Schuman, J. S., Kagemann, L., Ishikawa, H., Wollstein, G.
• Format: Article
• Language: English
• Subjects: Biomechanical Phenomena - physiology; Biomechanics; Biomedical optical imaging; Computer Simulation; Finite Element Analysis; finite element models; Glaucoma; Humans; Image Processing, Computer-Assisted - methods; intraocular pressure (IOP); inverse modeling; Irrigation; lamina cribrosa (LC); Ocular Hypertension - physiopathology; Optic Disk - physiology; optic nerve head (ONH); Sensitivity; Strain; Stress; Tomography, Optical Coherence - methods
• ISSN: 0278-0062; 1558-254X
• DOI: 10.1109/TMI.2014.2312133

Optic nerve head (ONH) tissue properties and biomechanics remain mostly unmeasurable in the experiment. We hypothesized that these can be estimated numerically from ocular parameters measurable in vivo with optical coherence tomography (OCT). Using parametric models representing human ONHs we simulated acute intraocular pressure (IOP) increases (10 mmHg). Statistical models were fit to predict, from OCT-measurable parameters, 15 outputs, including ONH tissue properties, stresses, and deformations. The calculations were repeated adding parameters that have recently been proposed as potentially measurable with OCT. We evaluated the sensitivity of the predictions to variations in the experimental parameters. Excellent fits were obtained to predict all outputs from the experimental parameters, with cross-validated R2s between 0.957 and 0.998. Incorporating the potentially measurable parameters improved fits significantly. Predictions of tissue stiffness were accurate to within 0.66 MPa for the sclera and 0.24 MPa for the lamina cribrosa. Predictions of strains and stresses were accurate to within 0.62% and 4.9 kPa, respectively. Estimates of ONH biomechanics and tissue properties can be obtained quickly from OCT measurements using an applet that we make freely available. These estimates may improve understanding of the eye sensitivity to IOP and assessment of patient risk for development or progression of glaucoma.