In scaled reptiles, the ocular scales are those forming the margin of the eye. The name originates from the term oculus which is Latin for "eye" and, in the broadest sense, refers to a scale associated with the eye. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.
Prefixes are usually included to indicate the positions or locations of the individual scales:
Collectively these scales are referred to as circumorbital scales, circumorbitals, or a circumorbital ring.
Occasionally, the term ocular scale is used without a prefix, in which case it specifically refers to the brille, also known as the spectacle or eyecap. This is a transparent scale that covers and protects the eye. It is formed in embryonic snakes when the transparent upper and lower eyelids fuse together. Once hatched, a snake does not possess eyelids and the brille carries out some of these functions.