Infectious crystalline keratopathy in dogs and cats: clinical, in vivo confocal microscopic, histopathologic, and microbiologic features of eight cases

Disseminated idiopathic lipid keratopathy in a normolipemic cat

OBJECTIVE

To report a case of idiopathic lipid keratopathy in a normolipemic cat.

ANIMAL STUDIED

A 10-year-old neutered female European domestic cat.

RESULTS

A cat was evaluated for bilateral white corneal deposits. Slit-lamp examination revealed multiple, well-defined, round, stromal, cream-colored deposits of different sizes associated with generalized superficial corneal vascularization. Blood lipids were normal, and no history of travel to tropical locations or ocular trauma was present. Topical betamethasone/gentamicin 0.1% suspension q 12 hours did not result in any improvement of clinical appearance after one week. Tomography following the initial therapy revealed dense, hyperreflective deposits with posterior shadowing in the anterior and mid stroma of both corneas. A four-week course of itraconazole 0.01% ophthalmic cream was prescribed q 12 hours with no improvement. Four months after the initial examination, a diagnostic superficial keratectomy and amniotic membrane implantation were performed. Histopathological analysis showed membrane bound vacuoles with infiltration of foamy macrophages suggesting a diagnosis of primary lipidosis. The post-surgical period was unremarkable, and ten days later, the patient was re-examined. Opacification from a corneal leukoma was observed in the excision site with mild fibrotic tissue. Two months post-keratectomy, no further changes were detected in the cornea, and the patient was managed only with topical lubricant.

CONCLUSIONS

To our knowledge, this is the first report of idiopathic corneal lipidosis in a cat and may be considered as a differential diagnosis of corneal disease in felines.

Applications of in vivo confocal microscopy in the management of infectious keratitis in veterinary ophthalmology

In vivo confocal microscopy (IVCM) is a relatively new ocular imaging technique that permits morphological and quantitative assessment of the living cornea on the cellular level. The applications for IVCM in clinical ophthalmology are numerous and diverse. There are several advantages inherent to IVCM over standard diagnostic techniques currently used to confirm a diagnosis of infectious keratitis in veterinary ophthalmology. With IVCM, images can be viewed in real-time providing immediate diagnostic information. Traumatic corneal sampling techniques are avoided, and the procedure can be repeated as frequently as is clinically indicated without risk of corneal tissue damage. Both superficial and deep corneal lesions can be evaluated by IVCM in an atraumatic fashion. Microorganism viability is not required for their detection and specialized diagnostic laboratory assay procedures are not necessary. Many larger infectious agents can be directly identified within corneal lesions by IVCM, including fungi and parasites such as Acanthamoeba spp. In other situations, such as bacterial infectious crystalline keratopathy, the biological systems associated with the microorganism can be detected within the cornea. The current resolution of IVCM is inadequate to directly visualize some corneal infectious agents, such as herpesviruses, but host responses and virus-infected epithelial cells can be identified. This review summarizes the current knowledge and applications of IVCM in the management of infectious keratitis in veterinary ophthalmology, including its use in animals with bacterial, fungal, parasitic, and viral keratitis.