In hypermetropia the retina is in front of the principal focus of the eye.
It is thought to be caused by hypermetropia and/or anisometropia as well as by the various types of squint.
Such cases should be treated with convex lenses, which should be theoretically of such a strength as to fully correct the hypermetropia.
Practically it is found that a certain amount of hypermetropia remains latent, owing to spasm of the accommodation, which relaxes only gradually.
At first glasses may be given of such a strength as to relieve the troublesome symptoms; and the strength may be gradually increased till the total hypermetropia is corrected.