Etiology:  The tendency to develop microphthalmia is not due to a specific mutation.  However, specific mutations may influence the possibility of developing microphthalmia, perhaps due to “environmental” influences.

Incidence:  Common, occurring in inbred strains of C57BL mice.  It is more common in female vs. male mice, and in the right vs. left eye.

Clinical signs:  The eye appears partly closed because the small globe does not support the lids.  Affected mice often develop recurrent ocular infections.

Pathology:  Histologic findings include central corneal opacities, iridocorneal and corneal-lenticular adhesions, abnormal formation of the iris and ciliary body, cataracts, extrusion of lens cortical material with dispersion throughout the eye, failure of vitreous development, and retinal folding [7].

Diagnosis: The diagnosis can be made on gross examination alone.

7. Richard S. Smith, J.P.S. Inbred C57 Black Mice: Microphthalmia and Ocular Infections. JAX Notes, 1995.