Conjunctivitis ligneous, also called recurrent membranous conjunctivitis, is an uncommon form of conjunctivitis. Conjunctivitis, also called pinkeye, is an infection of the conjunctiva, which is the membrane that lines the inner eyelid and the white part of the eyeball. Although an exact cause is not known, conjunctivitis ligneous may be caused by a viral infection or chemical irritants. The main characteristic of conjunctivitis ligneous is the formation of fibrinous exudates, a wood-like structure, on the surface and inside of conjunctiva (membrane of eye and eyelid). Although the formations may be removed, sometimes conjunctivitis ligneous is recurrent and comes back after removal. Membranes can eventually develop granuloma, a collection of immune cells that are trying to remove the infection. There are not many effective treatment options for conjunctivitis; antibiotics may be used to prevent secondary infection in other parts of the eye and body, but they do not lessen the severity of symptoms or shorten the disease.