The adjective ocular means “pertaining to an eye”
something possessing eyes is oculate, and a person who
studies and understands eyes is an oculist
practising oculism (but an ocularist is a person who makes glass eyes).
Doctors have a whole collection of eye-related words
that need not detain us for long. Examples include
supraocular (“above the eye”), periocular (“around the eye”)
and the grim exoculation (“removal of an eye”), but there are many more.
Monocular once meant “having one eye”, but that task has largely been taken over
by monoculous, leaving monocular to deal with “pertaining to one eye”. A monocule
is a creature with only one eye; a monoculist, monoculus
or monoculite is a one-eyed person. And of course a monocle is a single eye-glass.
Binocular has similarly surrendered the meaning “having two eyes” to binoculate
reserving “pertaining to two eyes” for it’s own use. A binocle is an opera glass—a
little pair of binoculars on a stick that can be used to observe the action on-stage.
For those with greater numbers of eyes than two, we have
trinocular (three), senocular (six), octonocular (eight),
centoculated (one hundred, reserved for the mythical all-seeing giant Argus Panoptes)
and the noncommittal multiocular (many).