As described by Fuchs1 and Fox,2 an individual susceptibility or idiosyncrasy occurs in drug conjunctivitis. This may follow preparations like mild mercurous chloride and yellow mercuric oxide, which are used in the treatment for conjunctivitis eczematosa and may produce an irritative conjunctivitis and involvement of the surrounding skin. Fox2 found that particularly the prolonged use of cocaine and atropine and occasionally physostigmine and homatropine resulted in a follicular catarrah of the conjunctiva and considerable swelling of the lids. Duane1 compared this susceptibility to drugs with hay-fever sensitivity. He believed that in susceptible persons, following the initial contact of the conjunctiva with pollen granules an inflammation occurs. This susceptibility is increased by the patient's having had one attack of the disease, and later contact of the conjunctiva, even with minute quantities of the pollen, causes a recurrence of the disease. Similarly, drugs, not poisonous to the