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Ocular Toxocara canis infection causing larval granulomatosis and leading to chronic endophthalmitis and retinal detachment is a well-defined cause of unilateral leukokoria in children. The computed tomographic (CT) scan revealed a diffuse, nonenhancing, well-defined hyperdense lesion occupying most of the globe. The CT findings do not definitively differentiate the diffuse endophthalmitis of larval granulomatosis from retinoblastoma or other pseudogliomas.

The distribution of Toxocara canis larvae in the eye was determined for mice given a single challenge dose (C-mice) as compared to mice similarily challenged after 2 or 3 previous infections (SC-mice). Controls were mice given only the 2 or 3 previous infections and uninfected mice. Eyes were observed in situ during a 34 day post-challenge period to compare inflammatory responses in the anterior eye; histologic examination of serial sections of the eyes of these mice was done at the end of this period. In situ observations showed that lesions in the anterior eye converted from hemorrhagic to white cell more rapidly in the SC-mice; white cell lesions were predominant in SC-mice as early as day 5, whereas similar predominance in C-mice was not noted until days 16–21. Histology revealed that approximately 90% of these eyes were infected. Worm burdens per eye correlated more closely with total dose per mouse than with the effects of immunization. Histologic study showed that 90% of larvae observed were in the retina, but that most lesions were in the uveal tissues which harbored only 0·8% of the total number of larvae.

This study was designed to compare the sensitivity and specificity of enzyme linked immunosorbent assay (ELISA) for the serodiagnosis of ocular toxocariasis using Toxocara canis embryonated egg antigen (TEE) and toxocara excretory-secretory or exoantigen (TEX) produced in vitro. TEE and TEX ELISA were comparably sensitive, but TEX ELISA was better able to discriminate between serum samples from patients with ocular toxocariasis and those from patients with retinoblastoma. In addition, preabsorption of sera with Ascaris suum embryonated egg antigen seemed to be essential to prevent false positive results with TEE ELISA but was not so critical for TEX-ELISA. Further studies are still required to standardise TEX for serodiagnosis.

Since Wilder (1950) observed an exceptional case of nematode Endoph-thalmitis and Nichols (1956) was able to identify it as ocular toxocariasis, fully authenticated cases have been described by several authors. Besides the symptoms of visceral larva migrans (Beautman & Woolf 1951, Beavers et al 1952, Brain & Allan 1964) lesions of the eye can be conceived as isolated (Duguid 1961, Laqua 1972, Siam 1973) or multiple granulomata located in the posterior region of the fundus and in a massive extension of the infestation as a chronic disseminated endophthal-mitis (Perkins 1968).

Enzyme-linked immunosorbent assays (ELISAs) may be made by a variety of techniques at one or several serum dilutions which is very confusing for clinicians. This study compares the ELISA results from two centres on sera from 12 patients investigated for ocular toxocariasis by two common ELISA methods--the absorbance and titration techniques. With one exception, ELISA results by the two methods correlated well. For reasons outlined, the absorbance ELISA method is likely to remain the preferred method in New Zealand and Australia. Attention is drawn to the implications of the serum response to Toxocara canis larvae, and the need to evaluate ELISA results against clinical findings is emphasized.

RESUMEN La toxocariasis es una zoonosis parasitaria. Se describen las alteraciones anatómicas y funcionales producidas por membranas que traccionan el polo posterior y la periferia de la retina, las cuales provocan hemorragia vítrea parcial asociada a neovascularización del disco óptico con membrana epirretiniana, y un agujero macular lamelar relacionado con la presencia de granuloma periférico. Se presenta un caso clínico de un paciente sano, quien comenzó con disminución de la agudeza visual del ojo izquierdo y se le diagnosticó, por cuadro clínico y examen oftalmológico con resultado positivo de la prueba de Toxocara, una toxocariasis ocular complicada. Se le realizó cirugía de vitrectomía mínimamente invasiva 23 G asociada a membranectomía, y pelado de la membrana limitante interna, así como endofotocoagulación con láser panretiniana. Se usó como tamponador al final de la cirugía el gas SF6 y el posicionamiento del paciente. Se aplicó tratamiento antiparasitario y esteroideo sistémico previo a la cirugía, y se obtuvieron resultados satisfactorios tanto anatómicos como funcionales del paciente.