When we examine the posterior segment of the eye we tend to think that we are looking for problems in the retina. I reality we are seeing the vitreous humor, the neural retina and optic nerve, retina pigment epithelium, the vascular coat lining the back of the eye – the choroid, and the outer fibrous coat of the eye – the sclera. The fundus is the area including all of these structures as seen by ophthalmoscopy through the pupil.
When presented with exotic species with ocular disease it is important to remember the concept of "the same and different". Eye are eyes regardless of the species and many of the conditions we are presented with in pocket pets and other exotic species are in many ways the same as those we have come to recognize in the more usual domestic species and can be diagnosed and treated empirically in the same way.
Many ocular conditions seen in cats are identical to those in other domestic species however there are eye diseases which are only seen with any frequency in cats (eyelid agenesis, diffuse iris melanoma) or which have common and unique presentations in the cat compared with other species (immune mediated uveitis and ocular eosinophilic disease).