ABSTRACT
The author reviews some aspects of vision and ophthalmic disease in the horse and considers how some recent developments in ocular immunobiology and molecular pathology in other species may give pointers toward an understanding of disease processes in the horse.
Subject(s)
Eye Diseases/veterinary , Horse Diseases/diagnosis , Animals , Eye/pathology , Eye Diseases/diagnosis , Eye Diseases/pathology , Horse Diseases/pathology , HorsesABSTRACT
OBJECTIVE: To describe the clinical findings and prognosis for extraocular lymphoma in the horse. PROCEDURES: Retrospective medical records study of horses diagnosed with third eyelid, corneoscleral, conjunctival, and/or eyelid lymphoma from multiple academic and private veterinary institutions. Data collected from the medical records included signalment, clinical descriptions of the extraocular lesions, treatment, and treatment outcomes. Nonparametric statistical analysis was performed with Fischer's exact tests. RESULTS: Extraocular lymphoma involving the eyelid, third eyelid, cornea, sclera, and/or conjunctiva was diagnosed in 26 horses. Differences in signalment, unilateral vs. bilateral extraocular involvement, and single vs. multiple extraocular lesion locations held no significance in terms of outcome. ANIMALS STUDIED: Horses with lesions localized to the eyelid or other nonextraocular cutaneous locations had a significantly higher chance of negative outcome when compared to the horses with no eyelid or cutaneous involvement (P = 0.019). Lesions to the third eyelid, corneosclera, and conjunctiva were either nodular or diffuse in nature. Nodular lesions when compared to diffuse lesions were associated with a higher chance of a positive outcome (P = 0.007). Surgical resection of the extraocular lesions as part of the treatment produced a statistically higher chance of a positive outcome when compared to horses where resection was not performed (P = 0.03). CONCLUSIONS: The prognosis for clinical remission in horses with extraocular lymphoma is generally fair to good, as long as the affected tissues are completely excised, and there is no eyelid or cutaneous involvement. Horses diagnosed with the nodular form of extraocular lymphoma seem to have the best prognosis with complete excision.
Subject(s)
Eye Neoplasms/veterinary , Horse Diseases/pathology , Lymphoma/veterinary , Animals , Conjunctival Neoplasms/diagnosis , Conjunctival Neoplasms/pathology , Conjunctival Neoplasms/veterinary , Corneal Diseases/diagnosis , Corneal Diseases/pathology , Corneal Diseases/veterinary , Eye Neoplasms/diagnosis , Eye Neoplasms/pathology , Eyelid Neoplasms/diagnosis , Eyelid Neoplasms/pathology , Eyelid Neoplasms/veterinary , Female , Horse Diseases/diagnosis , Horses , Lymphoma/diagnosis , Lymphoma/pathology , Male , Prognosis , Retrospective StudiesABSTRACT
It is conservatively estimated that some form of lens opacity is present in 5% to 7% of horses with otherwise clinically normal eyes.These opacities can range from small epicapsular remnants of the fetal vasculature to dense and extensive cataract. A cataract is defined technically as any opacity or alteration in the optical homogeneity of the lens involving one or more of the following: anterior epithelium, capsule, cortex, or nucleus. In the horse, cataracts rarely involve the entire lens structure (ie, complete cataracts) and are more usually localized to one anatomic landmark or sector of the lens. Complete cataracts are invariably associated with overt and significant visual disability. Focal or incomplete cataracts alone seldom cause any apparent visual dysfunction in affected horses,however.
