DIVERGENT SQUINT.
If we want to draw a comparison between convergent and divergent squint, we must consider only absolute divergent strabismus, for convergent strabismus does not offer a parallel to relative divergent squint. In absolute divergent squint the direction of the visual axes is such that they would meet behind the patient's head; in the relative divergent squint the axes of vision are parallel or slightly convergent, but they do not cross at the point fixed by the one eye, but at a greater distance off.
If we then only compare that which admits of comparison, we first find out that divergent squint is rarer than the convergent form, and the cause contained in the ocular muscles is here brought to light still more clearly than there.
We must next distinguish between permanent and periodic squint, and we see the latter so frequently continue as such, that we must not consider the transition from this variety to the permanent one to be the rule.
In 183 cases of absolute divergent strabismus which appeared in my private practice in the same space of time as the cases of convergent squint above discussed I have been able to obtain exact determinations of the refraction and visual acuteness. The weakness of the fixing eye was the test for classing them among the statistics, and in patients who had been long under observation, the first certain determination of refraction, which was necessary, as several children are included who came under treatment with divergent strabismus and emmetropia whilst myopia developed itself later.
A. Divergent squint with hypermetropia.
(a) Permanent 4 cases. Visual acuteness of the squinting eye more than 1/7 1 case, V. less than 1/36 1 case, 2 excluded, one on account of complication with detachment of retina, the other on account of impossibility of testing vision.
(b) Periodic squint 5 cases. Among them 3 with double hypermetropia, 2 with emmetropia in one, and hypermetropia in the other eye. Visual acuteness of more than 1/7 in 3 cases; V. = 1/9 1 case; V. = 1/36 1 case.