Compound eye

Many visual units

Ocellus

Simple light detector

Eyespot (Stigma)

Light-direction sensing

Pit eye

Pinhole vision

Cup eye

Directional light perception

Reflecting eye

Mirror-based focus

Apposition compound eye

Daylight compound vision

Superposition compound eye

Low-light compound vision

Faceted eye

Hexagonal visual units

Infrared pit organ

Heat detection

Polarization-sensitive eye

Detects light angles

Ultraviolet-sensitive eye

Sees UV light

Trichromatic vision system

Three color channels

Tetrachromatic vision system

Four color channels

Eyestalk-mounted eyes

Mobile visual organs

Cephalopod camera eye

Vertebrate-like, inverted-free

Parabolic lens eye

Enhanced light gathering

Reduced vestigial eyes

Minimal or nonfunctional

Extraocular photoreceptors

Vision outside eyes