Some of the morbid actions of the straight muscles and cornea of the eye explained : and their treatment considered / by Everard Home.

  • Home, Everard, Sir, 1756-1832.
Date:
[1797]
Catalogue details

Licence: Public Domain Mark

Credit: Some of the morbid actions of the straight muscles and cornea of the eye explained : and their treatment considered / by Everard Home. 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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    takes place; one where the muscles of the eye do not corre- spond in their action, and therefore the two eyes do not bear equally upon the object; the other, where some change has taken place in the refracting media of one eye which prevents the pencils of light from impressing the corresponding parts of the retina of both eyes. Instances of double vision produced by these two modes have fallen under my notice. It has been long ascertained by experiments, that when the eyes are not turned equally towards an object, it appears double, and the disease in the muscles which produces this effect is the subject which I now mean to consider. It will, at the same time, be proper to distinguish this kind of double vi- sion from that which is produced by a change in the refracting media of the eye; and this will be best done by explaining the nature of those changes in consequence of which it occurs. When one eye has had the crystalline lens extracted, the other remaining perfect, objects seen by both eyes will appear double. This is a fact which was noticed in a former lecture, in treat- ing of the adjustment of the eye. At first it appeared difficult to account for the double vision, particularly as the two images were entirely separate from each other. It could not arise from the absence of the lens, as that would not alter the situation of the images on the retina; and the two images being of different dimensions on similar parts of the retina, would appear to be -one before the other. As the operation of extracting the lens in no respect affects the muscles of the eye, the action of the mus- cles would be the same as before, and therefore could not con- tribute to produce this effect. The double vision in this instance appears to arise from the