Evaluation of equine corneal disease using ultrasound biomicroscopy

Well your average equine veterinary practice is not likely to have ultrasound biomicroscopy but a referral institution might. One of the problems in evaluating diseased equine eyes is that the cloudiness interferes with assessing depth and severity of the corneal disease. This procedure provides useful information in the diagnosis, treatment and prognosis before treatment is begun.
DrO

Evaluation of equine corneal disease using ultrasound biomicroscopy
Vet Ophthalmol. 2021 Mar 11.
Authors
Alessandra V Keenan 1 , Wendy M Townsend 2
Affiliations

1 Department of Clinical Sciences, Auburn University College of Veterinary Medicine, Auburn, AL, USA.
2 Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN, USA.

Abstract

Objective: To describe the clinical use of ultrasound biomicroscopy (UBM) to evaluate equine corneal disease.

Methods: Images were obtained using a 50-MHz probe ultrasound biomicroscopy system (Quantel Aviso) and Clear Scan® probe cover. Six horses with corneal disease were evaluated via UBM for lesion size, lesion depth, and continuity of Descemet’s membrane. Horses were sedated and received auriculopalpebral nerve blocks and application of topical anesthetic prior to UBM.

Results: Ultrasound biomicroscopy was easily performed in all cases. UBM evaluation of three cases of corneo-limbal squamous cell carcinoma yielded information regarding lesion depth for planning of keratectomies using fixed-depth keratomes and subsequent β-radiation therapy. Corneal depth and continuity of Descemet’s membrane were determined in two horses with stromal abscesses and allowed for planning of therapeutic options. In one horse with a corneal foreign body, UBM contributed to accurate assessment of the foreign body’s stromal depth, which could not be assessed during ophthalmic examination due to extensive corneal cellular infiltrate. The information regarding corneal depth allowed for more accurate pre-surgical planning in patients with opaque corneal lesions.

Conclusions: Ultrasound biomicroscopy was easily performed and provided useful information regarding lesion depth and continuity of Descemet’s membrane for patients with corneo-limbal squamous cell carcinoma, stromal abscesses, and a corneal foreign body, allowing for increased precision in pre-surgical planning and development of therapeutic protocols.

Keywords: cornea; corneal foreign body; equine; squamous cell carcinoma; stromal abscess; ultrasound biomicroscopy.