Facts Versus Theory 225
ness from non-use"-for in order to avoid the annoyance of double vision the mind is believed to suppress the image of the deviating eye. There are, however, many squinting eyes without amblyopia, while such a condition has been found in eyes that have never squinted.
The literature of the subject is full of the impossibility of curing amblyopia, and in popular writings persons having the care of children are urged to have cases of squint treated early, so that the vision of the squinting eye may not be lost. According to Worth, not much improvement can ordinarily be obtained in amblyopic eyes after the age of six, while Fuchs says,1 "The function of the retina never again becomes perfectly normal, even if the cause of the visual disturbance is done away with." Yet it is well known, as the translator of Fuchs points out in an editorial comment upon the above statement,2 that if the sight of the good eye is lost at any period of life, the vision of the amblyopic eye will often become normal. Furthermore, an eye may be amblyopic at one time and not at another. When the good eye is covered, a squinting eye may be so amblyopic that it can scarcely distinguish daylight from darkness; but when both eyes are open, the vision of the squinting eye may be found to be as good as that of the straight eye, if not better. In many cases, too, the amblyopia will change from one eye to the other.
Double vision occurs very seldom in squint, and when it does, it often assumes very curious forms. When the eyes turn in the image seen by the right eye should, according to all the laws of optics, be to the right, and the image seen by the left eye to the left. When the
1 Text-book of Ophthalmology, p. 633.
2 Cases have been reported, some surely authentic, m which an amblyopic squinting eye has acquired good vision, either through correction of the refraction, or because loss of sight in the good eye has compelled the use of the amblyopic eye.-Ibid.