On the morbid sensibility of the eye, commonly called weakness of sight / By John Stevenson.

  • Stevenson, John, 1778-1846?
Date:
1811
Catalogue details

Licence: Public Domain Mark

Credit: On the morbid sensibility of the eye, commonly called weakness of sight / By John Stevenson. Source: Wellcome Collection.

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    eye from the two vivid rays of light. They should, therefore, be reserved for urgent occasions, and only as a relief to the eye when it feels uneasy, from excessive irritation, or unusual exertions. At other times, I should prefer plain white spectacles.^ For by constantly wearing green, as the cornea be¬ comes with advancing: years less convex, the glasses must be rendered more so; till at length, such a degree of convexity is required, in order that they may converge the rays of light to a focus upon the retina, that the green glasses afford least aid, on account of * 1 cannot forbear announcing a recent improve® ment in tbe construction of spectacles, by which they are admirably and conveniently adapted to fulfil the above intentions. Opticians have lately contrived to fix both white and green preservers in the same frame, in such an ingenious manner, that either the one or the other glass can be used, without in the smallest degree incommoding the wearer, according as the eye may feel fatigued or inconvenienced by exposure toagreater or less glare of light, or by excessive exertions.