There have been 3 cases reported in the English literature1 and, recently, 2 in the American literature2 of a condition termed keratoconus posticus circumscriptus. The following case of a patient seen in 1940, which was written up at that time but not published, is of interest in that it may shed some light on the etiology of this minor, and apparently rare, abnormality. C. E. D., a 52 year old, white business man, consulted me for a refraction on Oct. 5, 1940. His only complaint was difficulty in reading for any length of time. He had worn glasses since childhood, and he volunteered the information that his left eye had never been as good as his right. His health had been excellent for many years. There was no unusual ocular condition in his ancestors. A son, in school, was myopic. No history of trauma was elicited. Examination disclosed