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.

Investigating the etiology of ocular changes in Monodactylus argenteus housed in a shoaling ring exhibit.

OBJECTIVE: To evaluate the pathologic ocular changes in a population of aquarium-housed Monodactylus argenteus and investigate potential underlying causes for the large number of affected fish in this exhibit. ANIMALS: 11 Monodactylus argenteus were evaluated from a shoaling ring exhibit within an aquarium, and 19 control fish without ocular abnormalities were obtained from commercial fish suppliers. METHODS: Physical and ocular examinations were performed antemortem. Postmortem samples of liver, heart, dorsal epaxial muscle, and lenses of affected and control fish were analyzed for amino acid profiles. The aqueous humor from affected and control fish was collected postmortem, and osmolality was analyzed. Tissues from affected and control fish were submitted for histopathology. RESULTS: Ocular abnormalities in affected fish included corneal lesions, cataracts, lens capsule rupture, and unilateral left-sided lens luxation and buphthalmos. Lens luxation and buphthalmos were directly correlated. Aqueous humor osmolality in control fish differed significantly compared to affected fish but was not correlated to lens abnormality score. Affected fish had significantly lower lens concentrations of arginine, asparagine, glycine, isoleucine, serine, and tyrosine than control fish. One affected fish had severe buphthalmos, cataracts, and panophthalmitis caused by gram-positive cocci. CONCLUSIONS: Cataracts and traumatic lesions were common in affected M argenteus. Dietary amino acid content and aqueous humor osmolality imbalances were not likely a cause of the cataracts. Differences in lens amino acid concentrations between affected and control fish may be related to cataract formation. CLINICAL RELEVANCE: Consideration of species-appropriate tank parameters may mitigate ocular lesions including cataracts in aquarium fish.

Assessment of Early Glaucomatous Optic Neuropathy in the Dog by Spectral Domain Optical Coherence Tomography (SD-OCT).

BACKGROUND: Inherited primary open-angle glaucoma (POAG) in Beagle dogs is a well-established large animal model of glaucoma and is caused by a G661R missense mutation in the ADAMTS10 gene. Using this model, the study describes early clinical disease markers for canine glaucoma. METHODS: Spectral-domain optical coherence tomography (SD-OCT) was used to assess nine adult, ADAMTS10-mutant (median age 45.6 months, range 28.8-52.8 months; mean diurnal intraocular pressure (IOP): 29.9 +/- SEM 0.44 mmHg) and three related age-matched control Beagles (mean diurnal IOP: 18.0 +/- SEM 0.53 mmHg). RESULTS: Of all the optic nerve head (ONH) parameters evaluated, the loss of myelin peak height in the horizontal plane was most significant (from 154 +/- SEM 38.4 µm to 9.3 +/- SEM 22.1 µm; p < 0.01). There was a strong significant negative correlation between myelin peak height and IOP (Spearman correlation: -0.78; p < 0.003). There were no significant differences in the thickness of any retinal layers evaluated. CONCLUSIONS: SD-OCT is a useful tool to detect early glaucomatous damage to the ONH in dogs before vision loss. Loss in myelin peak height without inner retinal thinning was identified as an early clinical disease marker. This suggests that initial degenerative changes are mostly due to the loss of myelin.