Special Senses: Eye

The mammalian eye is similar between mice and humans, with most gross and histologic differences due to relative sizing. Fixation of the eye and the retina in particular can be challenging due to poor penetration of fixatives through the sclera. In addition, routine formalin fixation can impart numerous artifacts, including separation of the retinal pigment epithelium from the outer segment of the retina. The average adult mouse eye is approximately 4 mm in diameter. The human eye measures 23.5-25 mm in diameter. In both species, the outer layer of the eye provides structural integrity and consists anteriorly of the optically clear cornea and posteriorly of the opaque sclera. The transition zone between the cornea and sclera is termed the limbus. Posterior to the limbus, the eye consists of three main layers (from external to internal): sclera, uvea, and retina. The space within the eye can be subdivided into three compartments: the anterior chamber, the posterior chamber, and the vitreous cavity. © 2012