Staining of the conjunctiva and conjunctival tear film

Both the distribution of tear fluid over the conjunctiva and any injury to the conjunctival epithelium can be made visible by instilling a fluorescent solution into the eye and observing with an appropriate combination of excitation and barrier filters. Sulphorhodamine B, which has an orange fluorescence that can be separated from the green natural fluorescence of the ocular tissues, gives a greater contrast than fluorescein. The tear film is seen to cover the surface of the conjunctiva and to be concentrated in its folds. Small circular areas of thin tear film appear transiently in the neighbourhood of the limbus after a blink. Occasional cells stain on the normal conjunctiva, particularly in the interpalpebral area. The density of the staining increases in dry eye conditions. Conjunctival trauma is sensitively revealed by the method, and its healing can be followed. Hard contact lenses are seen to traumatize continually the inferior limbal conjunctiva in symptomless wearers.