Medical Definition of Sclera

Sclera: The tough white outer coat over the eyeball that covers approximately the posterior five-sixths of its surface. The sclera is continuous in the front of the eye with the cornea and in the back of the eye with the external sheath of the optic nerve.

The word "sclera" is from the Greek "skleros" = hard. The plural is sclerae.

Source: MedTerms™ Medical Dictionary
http://www.medicinenet.com/script/main/art.asp?articlekey=16640
Last Editorial Review: 5/13/2016