A survey of the recent literature on keratoconus shows that the knowledge of this condition is far from definite ; certainly it is not suggestive of any new or promising line of research. A careful study of keratoconus was presented before the American Ophthalmological Society two years ago by Török and Redway,1 and Jaensch2 recently published a "Sammel-referat" which is exhaustive but not easy reading, so that one turns with relief to Collins and Mayou,3 in their classic "Pathology," to find that the problem of keratoconus can be summed up as an "Aberration in development due to some failure in the normal toughening process which takes place in the tissues." The question of keratoconus may be simplified by assuming the truth of the following statements : Keratoconus first attracts attention in adolescence, though it undoubtedly starts much earlier. Anatomic examination has demonstrated nothing but a stretching of