Subjective symptoms in eye diseases : being chapters on the disorders of vision symptomatic of diseases in the eye and central nervous system / by George A. Berry.

Berry, George A. (George Andreas), 1853-

Date:: 1886

Credit: Subjective symptoms in eye diseases : being chapters on the disorders of vision symptomatic of diseases in the eye and central nervous system / by George A. Berry. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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$their own objective examinations. A little more attention than is usually given to the various methods of examining accurately into the state of functional activity of the visual apparatus is to be advocated in both cases, as not only likely to lead to informa- tion interesting in itself, but also to be of value in directing them to the correct diagnosis of the cases which come under their treat- ment. Besides, however, affording evidence of the existence or not of pathological conditions in the eye itself, abnormalities found by subjective examination in the state of the visual functions, may be of such a nature as to reveal not only the presence of, but point more or less definitely to the site of lesions in the brain, and this, too, in cases when absolutely no clue is given by an ophthal- moscopic examination alone. A certain amount of intelligence on the part of the patient is necessary, of course, for a satisfactory subjective examination of any nature, and we must also be on our guard against unconscious or even wilful deception. We must remember, too, that in all such examinations we can only count upon obtaining approxima- tions to the actual state of matters. We cannot expect, nor need we aim at the accuracy to be got from physical experiments. Thus, in an examination of the field of vision, for example, we ought not to infer that there is an existing limitation of peripheral vision in any direction, unless the extent of the field is found considerably less in that direction than normal, and is otherwise normal in extent. Still less are we justified in coming to a hasty assumption of a concentric limitation, or the existence of improve- ment on subsequent examination, as there is a great individual difference in the power of observation in tests of that nature, and a greater accuracy generally acquired by practice. For the rest, many objective methods are subject to the same sources of error. It is not an uncommon thing, for instance, to meet men who believe they are able to determine the state of refraction to 1 dioptre, or even to £ dioptre, and yet a little consideration of the optical conditions would show that this degree of approximation is one which it could only be possible to attain to in cases where B$