Ocular Parasitic Infections

Ocular parasitology is the study of parasites that infect humans and result in ocular complications. Complications occur either due to mechanical, immunologic, or allergic reactions [1]. Because of protean manifestations and lack of clinical suspicion, the diagnosis is often missed. Prior to making a final diagnosis, ophthalmologists have to get dietary history, as most parasitic transmission is through food and water contamination. Travel history to endemic areas is important to determine the source of infection. When the humans are not the definitive hosts, but play the role of an accidental or intermediate host, the parasites do not mature into adult worms. Eggs or cysts are seldom found on stool examination. It is important for the ophthalmologists to understand the life cycle of the worm to select proper diagnostic tests (Table 13.1). Construction of an algorithm regarding management of ocular parasites is mandatory (Fig. 13.1). Sometimes patient may have associated systemic infestation (Fig. 13.2a, b). Careful systemic examination can aid in comprehensive treatment. There are several agents that can affect different ocular structures; clinical signs depend on the location and type of organism (Table 13.2).