A practical treatise on the morbid sensibility of the eye, commonly called weakness of sight / [John Stevenson].

  • Stevenson, John, 1778-1846?
Date:
1819
Catalogue details

Licence: Public Domain Mark

Credit: A practical treatise on the morbid sensibility of the eye, commonly called weakness of sight / [John Stevenson]. Source: Wellcome Collection.

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    I must, however, beg to remark, that there is a very essential difference between looking at, and through green. A greater exertion of the organ of vision is un- questionably required in using green than white glasses, on account of their opacity. The objects too, seen through them, ap- pear of a dingy yellowish hue (a defect which I admit, is greatly corrected by habit and experience), and when taken off, the impression, of light must be pro- portionally stronger, and consequently more injurious to the sight. By using green spectacles, especially those of a deep tint, the eye is subjected to fre- quent, and not inconsiderable variations in respect to the degree of light, which we have so often remarked a be. detri- . mental to the organ of vision. They can be considered as serving the purpose only