Student's guide to diseases of the eye / by Edward Nettleship ; with a chapter on examination for color perception by William Thomson.

Nettleship, Edward, 1845-1913.

Date:: 1883

Credit: Student's guide to diseases of the eye / by Edward Nettleship ; with a chapter on examination for color perception by William Thomson. 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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$stationary (Fig. 25). If each part of the field is equidistant from the part of the retina to which it corresponds, the field will form part of a hemisphere, with its inner or concave surface towards the eye; it may, however, be projected on to a flat surface, and for many clinical purposes this is quite accurate enough. For roughly testing the field, e. g., in a case of chronic glaucoma, or of atrophy of optic nerve, or of hemianopsia, the following is generally enough. Place the patient with his back to the window; let him Fig. 25. i t . \ . \ j&r~j\ so J \ 55/ ______ \^r 1A ' r-^^ (4 \y ■■■ ■ ] Field of vision with radius of 12, projected up to 45° on to a flat surface two feet square, r, fixation spot. cover one eye, and look steadily at the centre of your face or nose at a distance of 18 or 2'. Then hold up your hands with the fingers spread out in a plane with your face, and ascertain the greatest distance from the central point at which they are visible in various directions—up, down, in, out, and diagonally. It is essential that the pa- tient should look steadily at the face, and not allow his eye to wander after the moving fingers. A more accurate method is to make the patient gaze, 4*$