Abstract
Purpose :
To quantify biomechanical properties in a Col5a1+/- mouse model for classic type Ehlers-Danlos syndrome (EDS) and to compare two different measurement approaches suited for murine corneal mechanical characterization.
Methods :
A total of 14 adult eyes, 90 days old, of a Col5a1-haploinsufficient mouse model (Col5a1 het) and 14 eyes of the same age of wild-type littermates (wt) were analyzed by optical coherence elastography (OCE) and 2D stress-strain extensometry. Quasi-static OCE was conducted non-invasively during ambient pressure modulation by -3 mmHg. Corneal displacements were analyzed by phase-difference processing. 2D extensometry measurements consisted of a pre-conditioning cycle, followed by a stress-relaxation test and finally a rupture test.
Results :
Compared to wt corneas, Col5a1 het corneas had a thinner corneal thickness (125±11 vs 148±10 mm, p<0.001). Short-term elastic modulus in Col5a1 het corneas was significantly increased in OCT measurements (506±88 vs 430±103 kPa, p=0.023), and the same trend was observed in stress-strain extensometry (30.7±12.1 vs 21.5±5.7 kPa, p=0.057). In contrast, in stress relaxation tests, Col5a1 het corneas experienced a stronger relaxation (55% vs 50%, p=0.010). The two distinct behaviors indicate increased short-term stiffness and reduced long-term stiffness in het corneas.
Conclusions :
A reduced expression of collagen V in cornea seems to predominantly affect the viscoelastic properties of the tissue. The results presented here support and rationalize the counterintuitive clinical reported findings, in which even thinner corneas with potential alterations in the structure of collagen manage to maintain a normal topographic pattern.
This is a 2021 ARVO Annual Meeting abstract.