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Veterinary surgeon

Aoife Byrne

XLEquine practice

Chapelfield Veterinary

Partnership Ltd




The safety of a horse and its ability to do its work depends heavily on its


Whilst many horses can cope fairly well with compromised

vision, especially where this develops slowly, visual compromise

will not necessarily preclude the animal from being ridden.

Aoife Byrne DrMedVet MRCVS,

Chapelfield Veterinary Partnership Ltd

In this article five groups of

equine eye diseases will be


These are:

1. Keratitis

2. Uveitis

3. Lens luxation

4. Cataracts

5. Retinal disease and


In spite of this, there are many horses that

work well even though they have obvious,

compromising eye disease.

The outward evidence of ophthalmic disease

is obvious when blepharospasm (excessive

blinking), epiphora (overflow of tears), eye

rubbing, head tilt, obvious asymmetry of shape

or size when compared to the normal eye,

changes in the clarity of the cornea and

obviously abnormal discharges are seen.

More subtle changes associated with

ophthalmic pain include downturned

eyelashes, drooping of the upper eyelid,

enophthalmos (eye drawn back into orbit)

and photophobia (sensitivity to bright light).

Corneal ulceration

(Figure 1)

is a potentially

sight threatening disorder requiring early

diagnosis, laboratory confirmation of

micro-organisms and appropriate therapy.

Viral, bacterial and fungal species may

be involved either as a primary cause

or as secondary infection and each requires

prompt therapy if serious ocular

complications are to be avoided.

Ulceration should be considered in every

acute or chronically painful eye and infection

should be considered in every corneal ulcer.

Fungal involvement s rare in the UK but

should be suspected with a history of corneal

injury with plant material or if the ulcer has

received prolonged antibiotics and has

shown no improvement.

Many early cases of ulcerative keratitis

present as minor corneal epithelial ulcers

or infiltrates with pain, blepharospasm,

epiphora and photophobia.


Figure 1: Superficial corneal ulceration

stained with fluoroscein dye