Mouse corneal transplant evaluation with topography and pachymetry using OCT

Abstract

Purpose : Mice are the most commonly used animal model for studying corneal transplantation. Currently, acceptance vs. rejection of mouse corneal grafts is determined based on a subjective corneal scoring (Holland et al. Cornea 1991). Here, we describe a new approach to mouse corneal graft evaluation using optical coherence tomography (OCT) based corneal topography and pachymetry.

Methods : Five Balb/c mice each received a syngeneic corneal graft in one eye, while five other Balb/c mice received an allogeneic corneal graft in one eye from C57BL/6 donors. Twenty eyes, including both control and transplanted eyes, from these mice were imaged within 90 days after transplantation with a spectral domain OCT. Using the Mouse Corneal Analysis Program (Liu et al. Exp Eye Res 2019), central corneal thicknesses (CCT) and curvatures were calculated, and topography and pachymetry maps were created. The Wilcoxon rank sum test was used to detect differences between syngeneic and allogeneic grafts.

Results : The anterior radii of curvature of allogeneic grafts (1305 +/- 135 um, mean +/- SD) were significantly greater than those of syngeneic grafts (1169 +/- 84 um) (p = 0.011). The posterior radii of curvature of allogeneic grafts (1464 +/- 112 um) were also significantly greater than those of syngeneic grafts (1128 +/- 72 um) (p = 1.3e-5). No significant difference in radii of curvature was found between the control groups (p > 0.1). The CCT of allogeneic grafts (229 +/- 107 um) was significantly greater than that of syngeneic grafts (133 +/- 28 um) (p = 0.0119). The control corneas in the allogeneic group (130 +/- 10 um) were also thicker than the control corneas in the syngeneic group (92 +/- 29 um) (p = 58e-3). The difference in corneal thickness and curvature between syngeneic and allogeneic grafts can be visualized in topography and pachymetry maps (Figure).

Conclusions : We compared syngeneic and allogeneic mouse corneal grafts using OCT-based topography and pachymetry. Corneal thicknesses and curvatures of allogeneic grafts were significantly greater than those of syngeneic grafts. These results represent a new quantitative approach for evaluating mouse corneal grafts.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure: Cornea topography and pachymetry maps of syngeneic (top) and allogeneic (bottom) mouse corneal transplants. The cornea curvatures (left and middle) were generally flatter in the allogeneic grafts, and corneal thickness (right) was higher in the allogeneic grafts.