The principles and practice of ophthalmic medicine and surgery / by T. Wharton Jones.

  • Jones, Thomas Wharton, 1808-1891.
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: The principles and practice of ophthalmic medicine and surgery / by T. Wharton Jones. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    skin of the lips for example, and the skin of the cheeks. Whilst the points of the two legs of a pair of compasses, when separated a very short distance from each other, are applied to the skin of the lips, the mind distinguishes the two impres- sions ; but when applied to the skin of the cheek, there is no distinct perception of two points, but a sensation as if one im- pression only were made. 1760. As impressions on the less sensitive skin of the cheek are perceived as if smaller than impressions on the more sen- sitive skin of the lips, so objects seen by the less sensitive circumferential part of the retina appear smaller than when seen by the most sensitive middle part; or, caeteris paribus, an imperfectly illuminated object appears smaller than one brightly illuminated. 1761. In amblyopy, objects appear smaller than natural, owing perhaps to the defective sensibility of the retina (amau- rotic micropy). Temporary hemiopy. 1762. The following is an account of Hemiopy, by Dr. Wollaston, as it occurred in his own person. I suddenly found, after violent exercise, two or three hours before, that I could see but half the face of a man whom I met; and it was the same with respect to every object I looked at. In attempting to read the name Johnson over a door, I saw only son ; the commencement of the name being wholly obliterated to my view. The loss of sight was towards my left, and was the same, whether I looked with the right eye or the left. This blindness was not so complete, as to amount to absolute darkness, but was a shaded darkness, without definite outline. The complaint was of short duration, and in about a quarter of an hour, might be said to be wholly gone, having receded with a gradual motion from the centre of vision ob- liquely upwards towards the left. 1763. More than twenty years subsequently, a similar attack occurred again, without Dr. W. being able to assign any cause whatever, or to connect it with any previous or subsequent in- disposition. The blindness, says he, was first observed, as before, on looking at the face of a person I met, whose left eye was to my sight obliterated. My blindness was in this instance the reverse of the former, being to my right (instead of the left) of the spot to which my eyes were directed ; so that I have no reason to suppose it in any manner connected with the former affection. * * * On this occasion the affection, after