A manual of diseases of the eye / by Charles H. May and Claud Worth.

  • May, Charles Henry, 1861-1943.
Date:
1924
Catalogue details

Licence: Public Domain Mark

Credit: A manual of diseases of the eye / by Charles H. May and Claud Worth. Source: Wellcome Collection.

    381/524 (page 325)
    requires a concave spherical lens to bring the sight up to J. The weakest lens which accomplishes this is the measure of the myopia. In young persons it is important to paralyze the ciliary muscle, so that spasm of accommodation will not cause the patient to select too strong a lens. The results are recorded as follows : R.E. V = /q, ~c~4 D. Sph. = £. The reduction in distant vision generally is proportionate to the degree of M. The myope is able to read the smallest print, but at a shorter distance than that which the emmetrope selects. The farthest distance at which he is able to read the finest print is his far point, and this is also a measure of his M. (p. 322). The Ophthalmoscope at a Distance shows an inverted image of the fundus which appears to move in the opposite direction to the examiner’s head. The Ophthalmoscope, Indirect Method.—The disc appears small, and seems to increase in size upon withdrawing the objective lens. The Ophthalmoscope, Direct Method.—The fundus cannot be distinctly seen until a concave lens is placed behind the mirror ; the weakest concave lens with which the details are seen clearly indicates the amount of myopia. Retinoscopy.—With the plane mirror and the observer at 1 metre distance, the shadow moves in the opposite direction (except when M. is less than 1 D.), and is reversed by the addition of concave lenses. The lens which causes reversal plus - 1 D. is the measure of the M. In high M. the shadow is very faint, but becomes plainer when concave lenses are added. Prognosis.—In low and moderate degrees of stationary myopia the prognosis is good. Progressive myopia is always a serious condition, especially when the choroidal and vitreous changes are marked; it may necessitate absolute cessation of all near work. In malignant myopia the prognosis is grave. Treatment consists in prescribing glasses where they are required and in avoiding anything which may lead to an increase in the myopia. In general terms, it is proper to give a full correction for