Modified Medial Canthoplasty for Correction of Euryblepharon in Two Horses

To describe a medial canthoplasty surgical procedure in two horses for correction of euryblepharon, secondary to microphthalmia, and following excision of retrobulbar fat prolapse.

A 1 year old thoroughbred mare was presented for small globes and chronic ocular discharge bilaterally. Ophthalmic examination revealed microphthalmos, euryblepharon, medial canthal pocket syndrome, and dacryocystitis bilaterally with no visual impairments. A 2 year old Appaloosa gelding was presented for evaluation of a smooth, subconjunctival mass anterior to the right globe in the medial canthus. Ophthalmic examination additionally revealed euryblepharon and mild lower eyelid ectropion.

A medial canthoplasty procedure followed by placement of a partial temporary tarsorrhaphy was performed bilaterally on the first horse and on the right side in the second horse. The nasolacrimal puncta were identified and cannulated for the duration of the procedure. The medial canthal eyelid margin was everted and excised just medial to the puncta. The resection site was closed in two layers to restore normal anatomic lid position. On the second horse, the prolapsed retrobulbar fat was excised prior to the shortening blepharoplasty, and the peribulbar tissue and overlying conjunctiva were closed in two layers.

Both horses experienced improvement in the clinical signs for which they were presented following surgery. Histopathology results confirmed a retrobulbar fat prolapse.

Medial canthoplasty may be an effective technique for improving functional palpebral anatomy in horses with euryblepharon.