Impairment of retinal function in yellow perch by metacercariae.

Histologic studies of fish from Douglas Lake, Cheboygan County, Michigan, USA show that spp. infect the lens of spottail shiners () and common shiners (). In contrast, infection was confined to the choroidal vasculature of yellow perch (), and the morphology of the pigment epithelium and retina in regions adjacent to the metacercariae was abnormal.