Peripheral ring opacity of the cornea.

(i) A 59-year-old Caucasian male presented at the casualty department complaining of pricking in the right eye. Symptoms were caused by a marginal infiltrate and this resolved on conventional therapy. A recurrence one month later also responded well. Each cornea presented an arcus senilis and, in the zone ofstroma affected by the arcus, an additional opacity could be seen. This was identical in each eye, and took the form of a striking, narrow, dense white ring in the stroma, passing forwards as a band from Descemet's to Bowman's membrane (Fig. l).