Lucidum

Because the function of the eye is to form an image on the retina, an eye focused on a distant object has a focal surface that approximately follows the reflective tapetum lucidum structure, which is the condition required to form a good retroreflection.

In fish A single biological instance of this is known: in flashlight fish of the family Anomalopidae (see Tapetum lucidum ).

Many catfish have a tapetum lucidum which may help enhance photon capture and increase low-light sensitivity.

Sensory organs The eyes can focus independently, and are specialized with a duplex retina that contains two types of visual cells for both day and night vision, and a tapetum lucidum which reflects onto the retina to enhance vision in the dark.

The combination of the eye's lens and the cornea form the refractive converging system, while the tapetum lucidum behind the retina forms the spherical concave mirror.