Abstract
Purpose :
Changes of scleral biomechanics play a critical role in optic nerve health. Analyzing scleral biomechanics could contribute to elucidating the etiology of glaucoma and altering their characteristics could prove to be an effective novel treatment for glaucoma patients. Here we tested the hypothesis that elastic fiber defects caused by genetic mutations result in changes in scleral biomechanics in mouse eyes.
Methods :
We measured the dynamic scleral biomechanical response of intact 16-week-old mouse eyes comparing two experimental groups: wild type (wt, n=5) and a newly created double mutant line (dbm, Fbn1C1041G/+;Lxol1-/-, n=7) with elastic fiber defects. Posterior sclera response was measured during cyclic intraocular pressure (IOP) variations within a physiological range at different IOP amplitudes (Δ= 5, 10, 15 mmHg) and different frequencies (f= 0.5, 1, 2 Hz). Scleral strain was measured around the optic nerve head region by a custom three-dimensional (3D) optical method (3D-Digital Image Correlation) to provide high dynamic acquisition rates (85 Hz). Cyclic IOP variations were induced and controlled by an ocular infusion device designed for high-accuracy dynamic mechanical analysis (Electroforce 5500) and measured by a high sampling rate piezoelectric sensor (Millar Mikro-Tip).
Results :
Biomechanical weakening was defined by the largest peak strain measured during 6-cycle IOP variations. Statistical comparison by unpaired t-test (Fig.1,2) revealed a significant biomechanical weakening (p<0.05) of the posterior sclera of dbm mice group during dynamic IOP changes in all loading conditions compared to wt mice.
Conclusions :
Targeted genetic defects in elastic fibers cause biomechanical weakening of posterior sclera in mice during physiological dynamic IOP variations. Such investigation could provide mechanistic insight into the role of biomechanics of the ONH in glaucoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.