The annual production of hydroquinone (p-dihydroxybenzene), a reducing agent widely used in industry and in photography, has steadily increased and now amounts to approximately 20 million lb. General poisoning from the substance is not a problem inasmuch as hydroquinone is not highly toxic. However, ocular damage may develop in workers employed in its manufacture. This has been known for many years and is generally attributed to hydroquinone and its readily formed oxidized derivative, the brownish colored quinone.
Short-term exposure to high concentrations of the dusts and vapors of these compounds causes symptoms and signs of nonspecific, acute irritation. More interesting are the peculiar conjunctival and corneal changes which appear after chronic exposure. After about two years a brown tinge of the conjunctiva and episclera develops in the interpalpebral area. In the following years the discoloration becomes more intense and spreads onto the cornea. At this stage vision is practically