TETRAZOLIUM—ALCIAN BLUE MIXTURE

The mucous thread in the inferior conjunctival fornix is vital‐stained specifically by a mixture of 1% tetrazolium and 1/4% alcian blue. A total of 307 eyes were examined in the slit lamp, and 101 of the vital‐stained mucous threads were microscoped and measured. Predominantly red staining of the mucous thread was found to indicate bacterial infectious conjunctivitis, and predominantly green staining indicated a sterile conjunctiva. The predominantly red staining in infectious conjunctivitis is due to myriads of enzyme‐containing, degenerate, neutrophilic leucocytes, while the green colour comes from mucous fibrils. In normal eyes the mucous thread comprises, on an average, 3.1 mm 2 mucus, 1.3 inm 2 vacuoles, and 0.02 mm 2 red areas. For acute infectious conjunctivitis the corresponding figures are: 3.5, 1.0, and 20.8 mm 2 , and for chronic infectious conjunctivitis: 1.9, 0.4, and 29.0 mm 2 . The tetrazolium‐alcian blue mixture is indicated in cases of conjunctival complaints (establishes diagnoses of infectious conjunctivitis and chronic simple conjunctivitis), but is contraindicated in the presence of lesions that are not covered by epithelium.