Chronic Endophthalmitis Due to Toxocara.

NEMATODE infestations of the eye evoked little or no interest until the middle of the 20th century when Wilder (1950), whilst carrying out a histological survey of 46 cases of pseudogliomata, found nematode larvae or their hyaline capsules in 24, and tissue reactions characteristic of nematode endophthalmitis in the remaining 22. At that time, the larvae found in Wilder's series were believed to be those of the hookworm, and it was not until 6 years later that Nichols (1956), when reviewing this series, ascertained that the larvae present in five eyes were in fact those of Toxocara canis. More recently, Irvine and Irvine (1959) reported one case in which a retinoblastoma had been diagnosed clinically but histological examination of the enucleated eye revealed only chronic endophthalmitis due to a larva of the genus Toxocara at the site of the clinical tumour. No ocular lesions due to Toxocara had been identified in Britain until Ashton (1960) described four cases of retinal granuloma in which the larvae of this genus were actually demonstrated, and thereby established not only that the larva existed as an entity in human disease in Western Europe, but also that it was capable of producing a granulomatous ocular lesion which previously had sometimes been labelled as exudative choroiditis and which had certainly not formerly been associated with Toxocara canis. The importance of this discovery lies not only in the finding of a new lesion attributed to the Toxocara, but more especially in the fact that all four eyes reported by Ashton had been enucleated because the lesion strongly resembled a retinoblastoma. Outside the field of ophthalmology, Beaver, Snyder, Carrena, Dent, and Lafferty (1952), during the investigation of eosinophilic granulomatous lesions of the liver, discovered portions of a larval nematode belonging to the genus Toxocara and, since this discovery, the larva has been located in human tissues by numerous workers, thus confirming the importance of Toxocara infestation as an aetiological agent in some diseases. No such case, however, has yet been reported in the United Kingdom, although the larva found by Beautyman and Woolf (1951) in the brain of a child and described as that of Ascaris lumbricoides may have been of this nature.