Standing superficial keratectomy provides long-term control of epithelial and stromal equine immune-mediated keratitis.

Overview

• This study evaluated the effectiveness of standing superficial keratectomy as a treatment for equine immune-mediated keratitis (IMMK), finding it provided long-term disease control with reduced reliance on daily medications.

Background

• Immune-mediated keratitis (IMMK) in horses is an inflammatory eye condition affecting the cornea, involving epithelial and stromal layers.
• Diagnosis can be challenging and typically requires detailed eye examinations and tissue analysis.
• In vivo confocal microscopy (IVCM) is a noninvasive imaging method to assess corneal cells and structures in detail.
• Histopathology involves microscopic examination of corneal tissue obtained through biopsy or surgery, providing definitive diagnosis.

Study Purpose

• To describe the characteristics (demographics) of horses diagnosed with epithelial or stromal IMMK using IVCM and/or histopathology.
• To assess treatment outcomes for these horses, focusing on medical management, episcleral cyclosporine implantation, and standing superficial keratectomy.

Methods

• Medical records from Cornell University Equine Hospital (2020-2024) were reviewed to identify horses definitively diagnosed with IMMK.
• Inclusion required diagnosis by IVCM and/or histopathology.
• Data recorded included age, sex, affected eye(s), diagnostic methods, treatments administered, and clinical outcomes.

Results – Patient Demographics

• Total horses included: 22
• Mean age: 16.9 years (±7.3 years standard deviation)
• Gender: 16 geldings and 6 mares (significantly more geldings affected)
• Eye involvement: 19 horses had one eye affected (11 right, 8 left), and 3 had both eyes affected

Results – Diagnostics

• IVCM was performed in 20 out of the 22 horses.
• Eight horses of those 20 also had histopathology after superficial keratectomy, showing diagnostic agreement with IVCM.
• Two horses had histopathology without undergoing IVCM.

Results – Treatments and Outcomes

• All horses initially received medical management aimed at controlling inflammation.
• Seven horses underwent episcleral cyclosporine implantation:
• Only 2 of these 7 horses had successful control of IMMK at last follow-up (median follow-up of 532 days).
• Ten horses underwent standing superficial keratectomy (a surgical procedure performed with the horse standing):
• IMMK was controlled in 9 out of these 10 horses at last follow-up (median follow-up of 692 days).
• One horse had disease recurrence 12 months after keratectomy.

Conclusions

• IVCM is a valuable, rapid, and noninvasive diagnostic tool for IMMK in horses, correlating well with histopathological findings.
• Standing superficial keratectomy is effective both as a diagnostic aid and as a treatment for equine IMMK.
• This surgical approach provides long-term disease control, reducing or eliminating the need for prolonged daily medical therapy.
• Compared to episcleral cyclosporine implantation, keratectomy demonstrated superior long-term control in this study cohort.

Significance

• Offers equine veterinarians a reliable diagnostic method combined with an effective treatment strategy for managing challenging immune-mediated corneal diseases.
• Improves long-term outcomes and quality of life for horses with IMMK by limiting chronic medication use and potentially decreasing recurrence risk.