The light-sense in strabismus, especially in the amblyopia of strabismus / by D. Matheson Mackay.

  • Mackay, Duncan Matheson.
Date:
[1906?]
Catalogue details

Licence: In copyright

Credit: The light-sense in strabismus, especially in the amblyopia of strabismus / by D. Matheson Mackay. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    and published on the conditions of the light-sense in the amblyopia of strabismus. I have, therefore, thought that I might venture to lay before this Society a note of the examination of the light-sense in a number of strabismic or amblyopic patients, which I made in 1903, in the, Liverpool Eye and Ear Infirmary, by permission of the honorary surgeons of that institution. In introducing this subject, may I remind you that by the light-sense is meant the power which the retina, or the visual centre, has of perceiving gradations in the intensity of illumination, without reference to the colour, size, or form of the object from which the illumination comes (1). In examining the light-sense one has to consider the threshold of sensibility, that is, the light-minimum (L.M.), and the threshold of discrimination (2), that is, the light-difference (L.D.),—the light-minimum being the smallest amount of light capable of being perceived, and the light difference being the smallest amount of light needing to be added to, or taken from, a certain perceived amount of light before the illumination can be observed to be different. May I remind you further of Bjerrunffs demonstration that in diseases primarily involving the choroid and retina there is a tendency to imperfect perception of light,—in other words, to increased light-minimum ; while in diseases primarily involving the nervous elements in the retina or optic nerve there is a tendency to imperfect By D. Matheson Mackay, M.D.