Examination of the Eye of the Horse

To be able to perform a proper ophthalmic examination it is necessary to have a bright focal light source such as a transilluminator or a direct ophthalmoscope.

The head is examined for symmetry, globe size, movement and position of the globe, ocular discharge, and blepharospasm. The general appearance of the eyes and adnexa is noted.

It can be useful to examine the angle of the eyelashes on the upper lid to the cornea of the two eyes, as droopiness of the lashes of the upper lid may well indicate blepharospasm, ptosis, enophthalmos, or exophthalmos. Normally the eyelashes are almost perpendicular to the corneal surface. The first sign of a painful eye often is the eyelashes pointing downwards.

Reflex testing

Making a quick, threatening motion toward the eye to cause a blink response and/or a movement of the head tests the menace response. This is a crude test of vision. Care is taken not to create air currents toward the eye when performing this test. Horses have a very sensitive menace response.

The horse should also quickly squint or “dazzle” when a bright light is abruptly shown close to the eye.

The palpebral reflex is tested by gently touching the eyelids and observing the blink response. [...]