VetOnIt clinical notes
The equine field eye exam: a systematic sequence
Dr. Rachel Allbaugh's systematic approach to the equine eye exam from Vet On It's Introduction to Equine Ophthalmology course: reflexes, the menace response, structure-by-structure examination and extra uses for the direct ophthalmoscope.
Updated · VetOnIt
Work through the exam in order
After pupillary light reflexes (a helper makes indirect reflexes easier to assess), test the palpebral reflex and menace response with the opposite eye covered, then examine structure by structure: orbit, adnexa including eyelids and third eyelid, then the ocular structures from outside in, finishing with ophthalmoscopy. [1]
Menace response and cranial nerves
The menace response evaluates conscious perception of vision. A horse that lacks both palpebral and menace responses yet is visual may have facial nerve paralysis. [1]
Cover one eye and make the menacing gesture from different visual axes to find deficits. If the horse simply closes the eye being tested when the other is covered, use a blinder instead. [1]
More from the direct ophthalmoscope
In horses the direct ophthalmoscope is useful beyond the fundus: the small circle beam helps detect aqueous flare and judge depth, and the slit beam shows corneal curvature, where flattening or indentation over an ulcer indicates stromal loss. [1]
Related lectures
References
- Introduction to Equine Ophthalmology (lecture recording, May 8 2026) VetOnIt lecture transcriptLecture source retained by VetOnIt.