Evaluation of equine corneal disease using ultrasound biomicroscopy

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.

A multimodal approach to management of ocular surface squamous cell carcinoma in horses

“…Additional approaches to the management of ocular surface SCC include the use of advanced imaging and genetic testing. Advanced imaging techniques such as ultrasound biomicroscopy have improved clinicians’ ability to assess the invasiveness of ocular surface SCC tumours (Keenan & Townsend, 2021). This high frequency ultrasound technique allows for visualisation and measurement of the depth of the tumour within the corneal stroma ( Fig ).…”

Corneal thickness and anterior chamber depth of the normal adult horse as measured by ultrasound biomicroscopy

“…Based on the ease of portability and increasing affordability, UBM has become a practical advanced imaging technique for use in equine ophthalmology. Clinical applications of UBM to investigate equine ocular pathology reported thus far include Descemet's membrane detachment, corneolimbal squamous cell carcinoma, stromal abscesses, and a corneal foreign body 6–8 …”

“…Clinical applications of UBM to investigate equine ocular pathology reported thus far include Descemet's membrane detachment, corneolimbal squamous cell carcinoma, stromal abscesses, and a corneal foreign body. [6][7][8] Despite the utility of UBM, references with normal measurements of the adult horse cornea and anterior chamber are lacking. To date, a single in vivo study has investigated central corneal thickness in growing juvenile horses, and a single ex vivo study determined scleral thickness in enucleated globes, with no reports of normal in vivo parameters for adult horse eyes yet published.…”

“…Ultrasound biomicroscopy (UBM) has proven to be a valuable diagnostic tool for evaluation of corneal and scleral disorders, anterior segment masses, the iridocorneal angle and ciliary cleft, as well as lens disorders in both human and animal patients. [1][2][3][4][5][6][7] Based on the ease of portability and increasing affordability, UBM has become a practical advanced imaging technique for use in equine ophthalmology. Clinical applications of UBM to investigate equine ocular pathology reported thus far include Descemet's membrane detachment, corneolimbal squamous cell carcinoma, stromal abscesses, and a corneal foreign body.…”

“…Ultrasound biomicroscopy (UBM) has proven to be a valuable diagnostic tool for evaluation of corneal and scleral disorders, anterior segment masses, the iridocorneal angle and ciliary cleft, as well as lens disorders in both human and animal patients 1–7 . Based on the ease of portability and increasing affordability, UBM has become a practical advanced imaging technique for use in equine ophthalmology.…”