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Home / Equine Research Bank / Vet Ophthalmol / Modified Medial Canthoplasty for Correction of Euryblepharon...
Veterinary ophthalmology2026; 29(2); e70165; doi: 10.1111/vop.70165

Modified Medial Canthoplasty for Correction of Euryblepharon in Two Horses.

Abstract: To describe a medial canthoplasty surgical procedure in two horses for correction of euryblepharon, secondary to microphthalmia, and following excision of retrobulbar fat prolapse. Methods: 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. Methods: 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. Results: Both horses experienced improvement in the clinical signs for which they were presented following surgery. Histopathology results confirmed a retrobulbar fat prolapse. Conclusions: Medial canthoplasty may be an effective technique for improving functional palpebral anatomy in horses with euryblepharon.
© 2026 American College of Veterinary Ophthalmologists.
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Publication Date: 2026-03-08 PubMed ID: 41795230DOI: 10.1111/vop.70165Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study reports a surgical technique called medial canthoplasty used to correct euryblepharon, an eyelid malformation, in two horses with associated eye conditions such as microphthalmia and retrobulbar fat prolapse.
  • The procedure improved eyelid function and clinical symptoms in both horses.

Introduction and Clinical Background

  • Euryblepharon is an abnormality where the eyelids are longer than normal horizontally, causing eyelid malposition.
  • In the cases presented, euryblepharon was secondary to microphthalmia (abnormally small eyeballs) and retrobulbar fat prolapse (fat pushing from behind the eyeball).
  • Clinical signs included:
    • Chronic ocular discharge
    • Medial canthal pocket syndrome (fold or pocket in the medial canthus area)
    • Dacryocystitis (inflammation of tear drainage system)
    • Lower eyelid ectropion (eyelid turned outwards) in one horse
    • Presence of subconjunctival mass due to fat prolapse
  • Neither horse showed vision impairment despite these anatomical abnormalities.

Subjects in the Study

  • A 1-year-old thoroughbred mare presented with bilateral small globes and ocular discharge.
  • A 2-year-old Appaloosa gelding presented with a smooth mass by the medial canthus of the right eye and mild lower eyelid ectropion.

Surgical Procedure

  • Medial canthoplasty was performed to correct the eyelid malformation:
    • The nasolacrimal puncta (tear duct openings) were identified and cannulated to protect tear drainage during surgery.
    • The medial eyelid margin was everted (turned outward) and tissue was excised just medial to the puncta to remove excess or malformed tissue.
    • The surgical site was then closed in two layers to restore the eyelid’s normal anatomic position.
    • A temporary partial tarsorrhaphy (surgical closure of part of the eyelids) was applied to support healing in the mare.
  • For the Appaloosa gelding:
    • The retrobulbar fat prolapse was excised prior to the eyelid reconstruction.
    • The surrounding tissue and conjunctiva were closed in two layers.
    • Medial canthoplasty was performed on the side with the mass (right eye) only.

Outcomes and Histopathology

  • Both horses showed clinical improvement post-surgery, indicating the correction of eyelid malposition and reduction of associated symptoms.
  • Histopathologic evaluation of the mass confirmed it was retrobulbar fat prolapse.

Conclusions and Implications

  • Medial canthoplasty is an effective surgical technique to restore normal eyelid anatomy and function in horses with euryblepharon.
  • The surgery can successfully address secondary complications like retrobulbar fat prolapse and chronic ocular discharge.
  • This approach may be beneficial in managing eyelid malformations linked with ocular abnormalities such as microphthalmia in equine patients.

Cite This Article

APA
Letourneau AR, Butler BA, Martinez PS, da Costa Martins B, Monk CS, Plummer CE. (2026). Modified Medial Canthoplasty for Correction of Euryblepharon in Two Horses. Vet Ophthalmol, 29(2), e70165. https://doi.org/10.1111/vop.70165

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 29
Issue: 2
Pages: e70165

Researcher Affiliations

Letourneau, Abigail R
  • Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
Butler, Brooke A
  • Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
Martinez, Paoul S
  • Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
da Costa Martins, Bianca
  • Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, USA.
Monk, Caroline S
  • Blue Pearl Pet Hospital, Malvern, Pennsylvania, USA.
Plummer, Caryn E
  • Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.

MeSH Terms

  • Animals
  • Horses
  • Horse Diseases / surgery
  • Female
  • Eyelid Diseases / surgery
  • Eyelid Diseases / veterinary
  • Blepharoplasty / veterinary
  • Blepharoplasty / methods

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