A Clinical Case from the Archives : 28/09/2004

This eight year old cat is presented to you as the observant owner had noticed ‘something different’ in the appearance of the left eye. What are the changes that have changed the appearance of this eye, what is the condition and what diagnotic and therapeutic steps might you take? Incidentally the owner is a young lady with two young children and another on the way – does that influence what you might test for and what you might advise?

The abnormalities include raised areas in the iris, which are lymphoid follicles, engorged and proliferating blood vessels in the iris, so-called rubeosis iridis, and grey circular lesions on the interior face of the cornea. These, seen in more detail here, are keratic precipitates (KPs), clusters of lymphoid cells deposited on the inferior corneal endothelium. In fact these lesions are so-called mutton fat KPs which may well be macrophages not lymphoid cells. There are some finer KPs higher up the cornea which are more likely to be lymphocytic. The retina cannot be visualised in this eye, as there is a vitreous flare of inflammatory cells, while the right eye is unaffected. Tonometry of both eyes showed the right to have an intraocular pressure of 18mmHg while the affected left eye had a pressure of only 13mmHg, confirming the diagnosis of uveitis. Numerous infectious agents may be involved from FHV-1, FIP and Bartonella henslae to FeLV, FIV and Toxoplasma. As these last three are most likely to be involved in this case serology for these would be valuable – assessing the Goldmann-Witmer coefficient (the ratio of aqueous to serum antibody titres) can be helpful but needs relatively invasive aqueous paracentesis. The big worry there is Toxoplasma gondii which, being a zoonosis, could be passed on to the children or the baby in utero – stringent hygiene precautions are essential.

 

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