Myopia (commonly called near-sightedness,) in its various phases / by Julian J. Chisholm.

  • Chisolm, Julian John, 1830-1903.
Date:
[1880]
Catalogue details

Licence: Public Domain Mark

Credit: Myopia (commonly called near-sightedness,) in its various phases / by Julian J. Chisholm. 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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    then will work irregularly, sometimes even spasmodically. Such irritable comractions may become more or less permanent, and keep the lens in an unrelaxed condition of greater convexity. All organs, when in use, need an over blood supply. Immedi- ately after taking a hearty meal, the stomach requires so much blood from the rest of the body to carry on digestion that, with many persons, a sensation of chilliness of the skin is occasioned. After much walking, our legs swell, as evidenced by our boot tops tightening around our engorged calves. After much mental work, the head feels full, and the brain, if visible, would appear reddened from an increased circulation. So it is with the eye. Eye-work is inseparably connected with the ordinary wear and fear of the organ in use, which calls for an additional amount of the nutrient fluids of the body to repair the loss. The intensity of eye work is measured not only by the length of time that the eye is being used, but also by the degree of con- traction of the ciliary muscle; and both conditions are insepara- bly connected with local congestion. When the intra-ocular muscles are thrown into spasmodic action; they induce and en- sure a temporary hyperaemia of the interior of the eye ball ; and, necessarily, an increase in the contents of this hollow organ. Should this condition of muscular activity be frequently excited, and for a long time kept up in an eye not yet hardened by the complete development and maturition of its protecting layers; the comparatively soft eye shell, as found in the child, shows a dis- position to yield at its weakest point where the optic nerve fibres enter the sclerotic coat, and the foundation for a posteriori aphy- loma is laid. Staphyloma is the term given to the bulging of the walls at the back of the eye, which, by elongating the antero- posterior diameter of the eye ball, makes the organ permanently near-sighted. When once the beautiful symmetry of the ocular walls is disturbed by this bulging, the eye never can legain its normal shape. It is ever afterwards liable to become further distorted, until it is seriously disturbed in its working capacity, and becomes a very near-sighted eye, which is ahvays a seriously diseased one,