Toxocara canis, commonly known as the dog ascrid, is a frequent parasite of the domestic dog. If the eggs of an adult worm are accidentally ingested by a human host, usually a child, a larval form of the worm develops that can survive for a limited period in various human tissues. The retina is one of these tissues and upon the death of this organism a granulomatous reaction occurs and a fibrotic mass is formed in the retina. This unusual ophthalmoscopic appearance is demonstrated by the presentation of three fundus photographs of patients with suspected Toxocara lesions. A knowledge of this parasite and its life cycle will aid in its recognition, treatment, and possible prevention.
犬弓首蛔虫，通常被称为犬蛔虫，是家犬常见的寄生虫。如果人类宿主（通常是儿童）意外摄入成虫的虫卵，就会发育出一种幼虫形态，这种幼虫可以在人体的各种组织中存活一段有限的时间。视网膜就是这些组织之一，当这种生物体死亡时，会发生肉芽肿反应，并在视网膜中形成纤维化肿块。三张疑似犬弓首蛔虫病变患者的眼底照片展示了这种不寻常的眼底镜表现。了解这种寄生虫及其生命周期将有助于对其进行识别、治疗和可能的预防。
