Diseases and injuries of the eye : a text-book for students and practitioners / by William George Sym.

  • Sym William George.
Date:
1913
Catalogue details

Licence: In copyright

Credit: Diseases and injuries of the eye : a text-book for students and practitioners / by William George Sym. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    is present the patient may either make no attempt to look at the object or else he moves the eye so as to cause the image to fall on several different points of the retina consecutively: the eye is not brought to rest at any special defined attitude. Central fixation may be lost as a result of disease of the macular region of either chorioid or retina, or in retro-bulbar affections where the nerve fibres belonging to the macula are involved. It is also lost sometimes in cases of strabismus which has come on early in life. It is not lost in affections of the anterior part of the eye, if vision exists at all. Field of Vision.—The simple clinical method of ascertaining the limits of the field of vision is to place the patient with his back to the light that he may have every advantage, and to stand opposite to him at a distance of 3 ft. or so while he fixes his right eye upon the surgeon’s opposite (left) eye (his own left one being kept closed). He is then asked to indicate the limits of his field by saying whether he sees the movement of the surgeon’s fingers as they are moved at the extreme limits of his field of vision above, below, etc., in a plane equidistant from the two. If these are perceived at the same moment that the surgeon perceives them himself, the field may be assumed to be normal. The perimeter is an instrument for the more precise determination of the limits of the field. It consists essentially of a quadrant caused to describe a hemisphere by rotation about the visual axis of the eye under examina- tion, a fixation spot being provided at the pivot on which the quadrant rotates. Along the quadrant a test object is caused to travel, and the exact point of its appearance when it is moved centripetally, or of disappearance when it is moved centrifugally, is recorded; the line joining the object at the critical point with the eye may form with the visual axis an angle of 6o° to 90° or more. There are
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