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Due to its strong vascularization, the eye can be a target organ of systemic diseases. The aim of this prospective study was to examine cats suffering from systemic diseases for acute, pathological, ophthalmological findings. Cats that were presented to the Clinic for Small Animals, Freie Universität Berlin over a period of 36 months suffering certain systemic diseases or defined laboratory abnormalities were examined for ophthalmological changes.
The inclusion criteria included evidence of anemia (hematocrit < 0.24 l / l), systemic hypertension (> 180 mmHg), diabetes mellitus or feline malignant lymphoma. An extensive diagnostic evaluation of the underlying disease including clinical examination, laboratory tests, diagnostic imaging, blood pressure measurement and, where appropriate cytology and / or histopathology was carried out. Furthermore, an eye examination with slit - lamp biomicroscopy, ophthalmoscopy, Schirmer – tear - test, fluorescein test, tonometry, and optionally a documentation by fundus photography were made. 80 cats with anemia, 45 cats with systemic hypertension, 28 cats with diabetes mellitus and nine cats with malignant lymphoma were included in the study. An assignment of the cats in more than one diagnostic group was possible.
Anemic cats were evaluated for severity and cause of anemia. 29 cats had a mild anemia (hematocrit 0.20 l / l to 0.24 l / l), 30 cats a moderate anemia (hematocrit 0.15 l / l – 0.19 l / l) and 21 cats had a high degree of anemia (hematocrit < 0.15 l / l). The cause of the anemia was acute blood loss in 31 cats, hemolysis in nine cats, an anemia of inflammatory disease (AID) in 15 cats, the cause was intramedullary induced in three cats and extramedullary induced in 12 cats. In 10 cats, the cause could not be determined. Overall, acute, pathological, ophthalmological changes were detected in 14 cats. A correlation was found between the severity of anemia and the occurrence of acute, pathological, ophthalmological findings. No correlation with the cause of the anemia could be demonstrated. Retinal bleeding was the main finding, but uveitis and retinal detachment were also seen. Of the 45 cats with systemic hypertension only six cats had any acute pathologic ophthalmologic changes. Acute pathologic ophthalmologic findings were unilateral in nine cats unilateral and bilateral in 30 cats. These included hyphema, iris hemorrhage, vitreous hemorrhage, retinal edema, retinal detachment, retinal hemorrhage, retinal degeneration, glaucoma and uveitis. There was no statistically significant difference in the level of systolic blood pressure in cats without, with unilateral and with bilateral, acute, pathological, ophthalmological findings. In cats with diabetes mellitus, chronic ophthalmological findings were also taken into account. A cataract was seen in seven of 28 cats, eight cats had a decreased - tear - test and retinal hemorrhages were found in two cats. Ocular abnormalities were found in eight of the nine cats with malignant lymphoma. Among the findings were protrusion of the nictitating membrane, exopthalmus, corneal defect, exposue keratopathy, Vitreitis, tortuous retinal vessels, uveitis, glaucoma, and subluxation of the lens. This study shows that ocular manifestations can be found in a majority of systemic diseases in cats. The eye examination should therefore be used as a diagnostic window. It can be a good tool to provide a systemic diagnosis, to initiate an appropriate therapy and also to give a prognosis.