On the Origin of the Relationship of Accommodation and Convergence

Abstract

I come to a question which is of highest importance, especially for pathology, aside from its physiological interest. The issue is whether the association between the innervations of the medial muscles and certain lateral muscles of the double eye are inborn or are established by long habit. The importance of the differentiation, as one will remember, throws light on the fact that myopia and hypermetropia are already apparent in the first years of childhood. The hypermetropic child must accommodate even with parallel lines of sight in order to see clearly, and with converging lines of sight he must accommodate much more strongly than is necessary for emmetropes, while the myopic child conversely need not let accommodation grow when converging with near vision in the same way as the normal person. If the association in question were not inborn, neither hypermetropes nor myopes would find difficulty in vision for objects of sight within their monocular accommodation range. Even with relatively small convergence of the lines of sight, the hypermetrope could call forth the higher degrees of accommodation tension without difficulty, while the myope in spite of strong convergence of the lines of sight would not be burdened by using his accommodation muscles very little or not at all.