General Veterinary Ophthalmology: Examination, Anatomy, and Clinical Reasoning
What to know cold
A candidate must be able to describe the ophthalmic exam in order and justify each step: menace response (central/cortical, learned, not a pupil test), dazzle and pupillary light reflexes (afferent vs efferent limb), palpebral reflex (CN V and VII), vestibulo-ocular and oculocephalic responses, and vision testing by obstacle course. Know the neuro-ophthalmic pathways well enough to localize a lesion: a blind eye with a fixed, dilated pupil points to the retina or optic nerve (afferent), whereas a normal pupil with absent menace suggests central disease.
Anatomy that gets tested: the tear film layers and the nasolacrimal drainage path; the three chambers and the blood-aqueous barrier; the lens supported by zonules; the tapetum lucidum (present in dogs and cats, absent in the pigmented superior region of some species) and its role in the tapetal reflex. Species differences matter: cats have a paurangiotic retina and a prominent tapetum; horses have a retinal vascular pattern with a star-shaped optic disc; birds have striated ciliary muscle and scleral ossicles.
Traps
Questions love to conflate the dazzle reflex (subcortical, tests retina/brainstem) with vision (cortical). Another trap: assuming a normal PLR excludes retinal disease - focal or unilateral lesions can spare the reflex. Also remember that the menace response is absent in very young animals and is a learned response, not a reflex.
Rule of thumb
Localize before you diagnose: decide whether the problem is adnexal, corneal, intraocular, or neuro-ophthalmic, then test the structure you suspect. A worked example: a dog with a dilated pupil, absent PLR, and normal fundus on the affected side - pursue optic nerve/retinal disease (or CN II lesion) before considering iris or lens causes, because the afferent limb is failing.