Illustrations of some of the principal diseases of the eye : with a brief account of their symptoms, pathology, and treatment / by Henry Power.

  • Henry Power
Date:
1868
Catalogue details

Licence: Public Domain Mark

Credit: Illustrations of some of the principal diseases of the eye : with a brief account of their symptoms, pathology, and treatment / by Henry Power. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    the external rectus ? According to v. Grafe, the answer can be obtained by a careful determination of the amount of movement possessed by the eye. If the sum of its move- ments are equal to those of the sound eye, then it is the result of excessive innervation and energy of the affected muscle; but if, as is more frequently the case, the sum of its mobility is diminished, then it is the result of paralysis of the antagonistic muscle. But, then, it may be asked, how is the amount of the move- ment possessed by the two eyes to be ascertained and com- pared ? The plan to be adopted is the following, which, indeed, should be pursued in every case that presents itself: —The attention of the patient should be directed to some object placed in the median line, a short distance in front of him. It will then be found that he fixes the object with the sound eye, whilst the affected eye deviates more or less to the outer or inner side, according to the kind and degree of squint present. This deviation is called the primary angle of deviation, and may be measured either by the plan adopted by v. Grafe, of making a dot of ink below the centre of the cornea, on the lower lid of each eye, and measuring the distance of the dot on each side from the inner canthus; or by the plan of M.M. Testelin and Warlomont, of notching the border of an eyelet- hole in a piece of card, cut to the form and size of the palpe- bral fissure; or by the little instrument constructed by Mr J. Z. Lawrence, which consists of an arc of metal, divided at the edges into degrees, which can be applied to the lower lid; or by the more complicated and expensive instrument of Meyer; or, lastly, by the simple mode proposed by Dr Steffan,1 in which a square piece of millboard, with an arc of 18 inches radius described upon it, to the degrees of which lines, emanating from one angle, radiate, is placed horizon- t;i]ly in front of tin- eve. The patient is then told to fix a 1 Ophthalmic Review, vol. ii.