Eyesight, good & bad : a treatise on the exercise and preservation of vision.

  • Carter, Robert Brudenell, 1828-1918.
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: Eyesight, good & bad : a treatise on the exercise and preservation of vision. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    care Is needed in order to abstain from making it. In technical language, the whole lateral extent of vision is called the Field of vision; and we are said to see directly with the central part of the retina, and in- directly with the lateral parts. Indirect vision is of great value for many purposes, • and especially for giving us information as to the directions in which it is desirable for direct vision to be exerted. On this account, the indirect is sometimes called the de- fensive part of the field ; since it gives warning of the approach of large objects, and saves people from being exposed to many dangers. There are certain diseases of the eye in which the outer part of the field of vision is lost, so that the sight is circumscribed as if by look- ing through a tube; and, in these cases, although central vision may be good, and the patient able to read small print, there is yet great difficulty in guiding the footsteps and in avoiding obstacles, especially moving obstacles as in the street. There are many persons with contracted visual field who in one sense can see tolerably, and yet who would not be safe in a crowded thoroughfare. The loss of lateral or indirect vision renders them unable to ascertain correctly the relative positions of objects, and entirely conceals from them many which they would require to see in order to guide their steps with safety. An exceedingly curious example of the effect of con- traction of the field of vision was lately related to me by an old gentleman, who had suffered from a malady which produces this effect, but whose remaining central