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Abstract #117564 Published in IGR 24-4
A Noninvasive Clinical Method to Measure in Vivo Mechanical Strains of the Lamina Cribrosa by OCT
Hannay V; Czerpak C; Quigley HA; Nguyen TDOphthalmology science 2024; 4: 100473
OBJECTIVE: To measure mechanical strain of the lamina cribrosa (LC) after intraocular pressure (IOP) change produced 1 week after a change in glaucoma medication. DESIGN: Cohort study. PARTICIPANTS: Adult glaucoma patients (23 eyes, 15 patients) prescribed a change in IOP-lowering medication. INTERVENTION: Noninvasive OCT imaging of the eye. MAIN OUTCOME MEASURES: Deformation calculated by digital volume correlation of OCT scans of the LC before and after IOP lowering by medication. RESULTS: Among 23 eyes, 17 eyes of 12 persons had IOP lowering ≥ 3 mmHg (reduced IOP group) with tensile anterior-posterior strain = 1.0% ± 1.1% ( = 0.003) and compressive radial strain () = -0.3% ± 0.5% ( = 0.012; random effects models accounting inclusion of both eyes in some persons). Maximum in-plane principal (tensile) strain and maximum shear strain in the reduced-IOP group were as follows: = 1.7% ± 1.0% and = 1.4% ± 0.7%, respectively (both < 0.0001 vs. zero). Reduced-IOP group strains and were significantly larger with greater % IOP decrease ( < 0.0001 and < 0.0001, respectively). The compliances of the , , and strain responses, defined as strain normalized by the IOP decrease, were larger with more abnormal perimetric mean deviation or visual field index values (all ≤ 0.02). Strains were unrelated to age (all ≥ 0.088). In reduced-IOP eyes, mean LC anterior border posterior movement was only 2.05 μm posteriorly ( = 0.052) and not related to % IOP change ( = 0.94, random effects models). Only was significantly related to anterior lamina depth change, becoming more negative with greater posterior LC border change ( = 0.015). CONCLUSIONS: Lamina cribrosa mechanical strains can be effectively measured by changes in eye drop medication using OCT and are related to degree of visual function loss in glaucoma. FINANCIAL DISCLOSURES: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland.
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