It is the thin, transparent, vascular mucous membrane covering the undersurface of the lids and is reflected over the anterior part of the eyeball up to the limbus. It consists of palpebral and bulbar parts and the fornices. Inflammation of the conjunctiva (conjunctivitis) may be infective or allergic which may have acute, subacute or chronic course. Conjunctivitis is evaluated by the type of discharge, characteristics of conjunctival reactions and presence of lymphadenopathy. It is treated by antibiotic drops and ointments. Acute conjunctivitis may be mucopurulent or purulent. Ophthalmia neonatorum is conjunctivitis occurring in the newborn usually due to maternal infection. Chronic conjunctivitis may be simple, angular or follicular. Trachoma is a type of chronic conjunctivitis caused by Chlamydia trachomatis. Conjunctivitis may also be allergic like phlyctenular conjunctivitis which is due to reaction to endogenous protein with bleb formation near the limbus. Vernal conjunctivitis is caused by exogenous allergens, usually occurring in young boys and may be palpebral, bulbar or mixed. Degenerative conditions of the conjunctiva include concretions, pinguecula and pterygium. Xerosis is dry, lusterless condition of the conjunctiva and may be due to deficiency of tears or mucus. Irregular corneal surface, insufficient resurfacing of the cornea, lipid layer abnormality and visual display terminal syndrome are other causes of xerosis. Treatment is by supplementation and preservation of tears.