The diagnosis of chronic simple conjunctivitis. Vital staining of tarsus with tetrazolium - alcian blue mixture.

Vital staining with a tetrazolium - alcian blue mixture gave a characteristic punctate red staining of the superior or the inferior tarsus in 69% of all examined patients with chronic simple conjuctivitis (69 patients subjected to 168 examinations). The superior tarsus was more frequently stained than the inferior (61% against 33%). The staining was most often concentrated centrally or in the middle anterior part of the superior tarsus. If located on the inferior tarsus, it was most often found medially, anteriorly. No corresponding staining was seen in normal eyes. The differential diagnosis involving keratoconjunctivitis sicca and pemphigoid is mentioned. The staining is due to enzymatic reduction of tetrazolium in the cytoplasm of the tarsal epithelial cells. The positive vital staining finding is consistent with a diagnosis of chronic simple conjunctivitis.