Experimental hematogenous endophthalmitis due to Cryptococcus neoformans.

New Zealand white female rabbits injected with 6 X 10(7) to 5.5 X 10(8) CFU of Cryptococcus neoformans into the right carotid artery developed three types of clinically detectable eye lesions. These eye manifestations included: (1) iritis that had distinctive 1-3 mm white nodules; (2) white vitreous lesions with ill-defined borders, and (3) focal and diffusely infiltrative lesions of the optic nerve radiations. Most of the eye lesions appeared between 1 to 3 weeks after intracarotid injection and resolved almost completely by 10 weeks. Their clinical appearance resembled some of the eye lesions described from human cases. Predominantly a mononuclear leukocyte response with scattered cryptococcal organisms were seen in the iris and optic nerve lesions. Serial quantitative cultures from eye tissues, brain, and kidney indicated that the clearance of viable cryptococci was slowest from the eye tissues. Among the three diagnostic techniques (India Ink mount, culture, and cryptococcal polysaccharide antigen (CPA) determination), the CPA determination was the most sensitive test to detect C. neoformans in the aqueous and vitreous humors of clinically involved eyes. This rabbit model may be useful for further studies on hematogenous cryptococcal endophthalmitis.