Iowa City, Feb. 5, 1894.
To the Editor:
—In the editorial on "Superfluous Glasses," in the Journal of February 3, there are several points which I can heartily indorse, and some, naturally, that seem to me not well taken. I write now because I am preparing an article on asthenopia, based on records of more than a thousand cases seen in private practice, nearly all among professional people and students. The notes do not cover refractive errors alone, but constitutional conditions, general and local diseases, etc. More than six hundred had errors of refraction, and while relief of refractive error has always been to the advantage of the patient, the cure of asthenopia, in my experience, often requires more than simply making the eye the most perfect optical instrument possible, or securing the so called equilibrium of muscular movement of both eyes. Asthenopia occurs with one eye, with emmetropia, hyperopia,