Figure 1. Credit: St Luke's Cataract & Laser Institute.
Figure 2. The conjunctiva is a transparent membrane that covers the sclera (the white of the eye) and lines the inside of the eyelids.
The conjunctiva is the thin, transparent, mucous membrane that covers the outer surface of the eye. It begins at the outer edge of the cornea and covers the visible part of the sclera and lines the inside of the eyelids. It is nourished by tiny blood vessels that are barely visible to the naked eye. The conjunctiva also secretes oils and mucous that moisten and lubricate the eye.
Medical conditions of the conjunctiva
Inflammation of the conjunctiva is known as conjunctivitis, or, commonly, pink-eye. Conjunctivitis is a common but usually harmless condition caused by allergy (as part of hay fever), foreign bodies, or infection with viruses or bacteria. It causes irritation, watering, and sticky discharge, but does not affect vision. Eye drops may help, as can antibiotics if bacteria are present.
A pinguecula is a small, benign, yellowish spot on the conjunctiva over the exposed areas of the white of the eye. Pingueculas are sometimes attributed to ultraviolet radiation in sunlight, and are common in elderly people. In some cases, pingueculas may be removed for cosmetic reasons.