<P> Manufactured retroreflectors modeled after a tapetum lucidum are described in numerous patents and today have many uses . The earliest patent, first used in "Catseye" brand raised pavement markers, was inspired by the tapetum lucidum of a cat's eye . A more recent use of retroreflectors, helping to provide secure communications between two stations in line of sight, is modeled after the combination of tapetum lucidum and bioluminescent "flashlight" in flashlight fish of the families Anomalopidae and Stomiidae . </P> <P> In dogs, certain drugs are known to disturb the precise organization of the crystals of the tapetum lucidum, thus compromising the dog's ability to see in low light . These drugs include ethambutol, macrolide antibiotics, dithizone, antimalarial medications, some receptor H - antagonists, and cardiovascular agents . The disturbance "is attributed to the chelating action which removes zinc from the tapetal cells ." </P> <P> Traditionally it has been difficult to take retinal images of animals with a tapetum lucidum because ophthalmoscopy devices designed for humans rely on a high level of on - axis illumination . This kind of illumination causes a great deal of reflex, or back - scatter, when it interacts with the tapetum . New devices with variable illumination can make this possible, however . </P> <Ul> <Li> <P> Heterochromatic dog with red - eye effect in blue eye </P> </Li> <Li> <P> Aye - aye </P> </Li> <Li> <P> Sportive lemur </P> </Li> </Ul>

Cats eye glows in the dark because of the presence of