Ultrasound biomicroscopic imaging parameters associated with outcome in equine infectious ulcerative keratitis and stromal abscesses.

OBJECTIVE: To determine the predictive value of corneal ultrasound biomicroscopy (UBM) findings for the outcome of equine corneal disease. ANIMALS: 46 horses with a clinical diagnosis of either infectious ulcerative keratitis or stromal abscess. METHODS: Corneal UBM (VevoMD; UHF70; VisualSonics) of horses with infectious corneal disease presenting to the North Carolina State University Equine Ophthalmology Service from 2019 to 2023 were evaluated. Size and depth of lesion, presence of Descemet membrane disruption (DMD), corneal thickness, and aqueous humor cell counts (AHCC) were assessed. Comparisons of UBM and clinical exam findings, presence of infectious organisms, and outcome (healed or enucleated) were performed. RESULTS: The UBMs from 46 horses were evaluated. Increased AHCC was significantly associated with increased size and depth of corneal lesions on UBM but not with DMD. Deep lesions and DMD were significantly associated with an enucleation outcome. Horses treated with systemic antibiotics had significantly lower AHCC on UBM, but there were no differences in AHCC with the use of other systemic or topical medications. There was no significant correlation between infectious disease results, clinical findings (aqueous flare or cells), outcome, and UBM AHCC. CLINICAL RELEVANCE: Parameters on UBM, such as depth of lesion, DMD, and AHCC, may be useful diagnostic and prognostic tools to augment the ophthalmic exam of horses with corneal disease. The UBM findings of deep corneal lesions and DMD suggest a poor prognosis and warrant aggressive surgical intervention.

Evaluation of equine corneal disease using spectral domain optical coherence tomography (SD-OCT).

PURPOSE: The purpose of this case series is to evaluate the use of spectral domain optical coherence tomography (SD-OCT) imaging in equine corneal disease to demonstrate the feasibility, diagnostic effectiveness, and limitations of this imaging modality. METHODS: Retrospective study: Handheld SD-OCT (Envisu, Bioptigen Inc, Morrisville, NC) was used for high-resolution imaging of horses with corneal disease presenting to the North Carolina State University Equine Ophthalmology Service from 2013 to 2018. RESULTS: Fourteen horses were included in this study, including six horses with corneal ulceration, three with stromal abscesses (SA), three with immune-mediated keratitis (IMMK), and two with ocular neoplasms. High-resolution images of the cornea were obtained using handheld SD-OCT in standing horses; however, acquiring images was time-consuming due to the inherent movement of the examiner and horse. Despite this, in horses with corneal ulcers, SA, and IMMK, SD-OCT assisted with determining location of disease in the cornea (eg, superficial, mid-stromal, endothelial) and if disruption of Descemet's membrane was present. In horses with neoplasia, the SD-OCT helped to determine whether the cornea had neoplastic invasion from anterior chamber masses. CONCLUSIONS: Results from this retrospective study suggest that handheld SD-OCT for imaging the cornea of horses is feasible and may be helpful in determining depth and extent of lesions in the cornea.