The article on "Muscle Imbalance in Myopia" by Marlow1 in the April issue of the Archives of Ophthalmology stressed an element in the etiology of progressive myopia which has been too long overlooked. In fact, in a lecture on myopia before the Section of Ophthalmology of the New York Academy of Medicine (Dec. 17, 1934) all possible factors in the etiology of myopia, simple and progressive, were enumerated and briefly discussed, but the rôle of exophoria as a factor was hardly mentioned. This oversight has now been corrected in Marlow's splendid contribution. However, there is still one phase which has not been fully presented and which I wish to discuss briefly.
Aside from axial myopia, due to stretching of the sclera, there is a slowly progressive, low grade myopia, especially in children, which does not seem to be connected with a stretching process ; it seems to be