Subconjunctival and systemic therapy may be advantageous when blepharospasm makes topical medication difficult. Horses who experience frequent recurrence may benefit from long term low dose prophylactic therapy, such as oral aspirin or phenylbutazone. Long term use of topical steroids for prophylaxis may predispose to corneal infection, and is therefore not advised. Atropine has been used commonly as an adjunct for treatment of uveitis. The mydriatic effect of atropine may persist for a week or longer, even after it is discontinued.
Mydriasis can increase intraocular pressure by partially closing the iridocorneal angle.
Because of this, tropicamide may be safer than atropine for use in uveitis. Tropicamide has the same beneficial effects as atropine, yet its duration of action is much less. If intraocular pressure rises after mydriasis, the effects of tropicamide will diminish within a day. The cornea must be examined carefully before use of topical and particularly subconjunctival steroids. Corneal ulcers can occur with uveitis, and management of the two conditions simultaneously can be challenging.