Haptoglobin knockout mice exhibit morphologic changes consistent with iridocorneal dysgenesis and glaucoma

Abstract

Abstract Purpose: To investigate the ocular phenotype of mice that lack the acute phase protein Haptoglobin (Hpko). Methods: Hpko mice were clinically evaluated at 16 weeks of age. Mice that showed macroscopic changes of the eyes were sacrificed and their eyes were enucleated, fixed in paraformaldehyde, histological sectioned and stained with hematoxylin and eosin. The diameter of the eye was measured and the histomorphology was evaluated and compared with eyes of normal wild‐type mice. Results: Clinical observation revealed that between 10 and 20 % of the Hpko mice exhibited gradual opacification of the cornea and shrinkage of the eyes . These mice were investigated. The eyes of Hpko mice were between 10 and 40 % smaller than eyes of normal mice. The eyes of Hpko mice showed rudimentary and more widely spread processi of the ciliary body. Moreover the anterior chamber showed goniosynechia and irido‐corneal adhesions, as well as attenuation of the trabecular meshwork. The neuroretina showed a variable atrophy in ganglion cell layers in all Hpko mice and in the inner nuclear and plexiform layer in 80 %. Conclusions: Haptoglobin knockout mice have structural abnormalities of the anterior segment and neuroretina comparable to human iridocorneal dysgenesis and developmental glaucoma.