VITAL STAINING OF CORNEA AND CONJUNCTIVA

It is a well-known fact that diseases of the cornea and the conjunctiva can be studied after instillation of a dye into the conjunctival sac. For different reasons vital staining in this region is particularly valuable. The stained structures can be studied microscopically in v ivo by means of the slit lamp, the structures are partially transparent, and the lacrimal fluid washes the area, so that the dye employed usually need not be washed away. It has recently been stated that certain forms of virus-provoked conjunctivitis are best diagnosed by vital staining with mercurochrome. This dye discloses punctate staining of the cornea, which is not otherwise demonstrable, more particularly not by staining with fluorescein (van de Velde). On the basis of this statement the question suggests itself whether we ought to use a greater number of the numerous previously published vital stains. Is the use of different vital stains for different diagnostic purposes indicated? The concept of vital staining was introduced by Ehrlich in 1886-87. It can be defined as staining of a living cell by a certain dye, which in a dissolved state comes into contact with the cell. The cell will then be distinguishable from other cells, which do not have this property. Vital staining of the cornea seems first to have been carried through with fluorescein. PfEiiger stained experimentally produced scratches in rabbit corneae. He saw that, in addition to staining the scratch itself, the fluorescein spread into the cornea, especially in the centripetal direction, suggesting that the fluid current in the cornea moves towards the centre of this. Straub and Fromm et al. have introduced fluorescein staining for clinical diagnosis and essessment of corneal abrasion, foreign body in the cornea, scratch from foreign body in the eyelid, corneal corrosions, dendritic keratitis, keratitis bullosa, xerosis corneae, keratitis filamentosa, corneal abscess, lagophthalmos, phlyctenae, etc.