The secondary larvae of the canine roundworm, Toxocara canis, attacks the liver, lungs, eyes, and brain. This condition, frequently called visceral larva migrans (VLM) syndrome, is an important cause of blindness in children. The ocular component of VLM is called ocular larval migrans, or OLM. It is frequently mistaken for retinoblastoma. The larva is absorbed into the system from the small intestine of children who have been infected while playing with puppies harboring the parasite. Because of its penetration into the central nervous system, these children may present with symptoms mimicking epilepsy or even a brain tumor. Ophthalmoscopically, a pseudoglioma may be present owing to the long standing presence of the larvae and the body’s immunological reaction to it. The larva, which is minute, is rarely seen during the acute stages of the infection. When seen during late disease, it may be observed in the temporal quadrants. It is best noted using serial photography over many visits. There may be retinal edema with a small hemorrhage at the site where the larva is present. As time progresses, there is more and more exudation as well as host reaction, making it difficult to see the larva. Patients with the chronic infection demonstrate the characteristic granuloma in either the posterior pole or periphery. The granuloma represents multiple bouts of chorioretinitis over a long period.
KeywordsAcute Stage Posterior Pole Host Reaction Demarcation Line Retinal Edema
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