Treatise on the diseases of the eye : including the anatomy of the organ / by Carl Stellwag (von Carion) ; translated from the fourth German edition and edited by D.B. St. John Roosa, Charles S. Bull, and Charles E. Hackley.
- Karl Stellwag von Carion
- Date:
- 1873
Licence: Public Domain Mark
Credit: Treatise on the diseases of the eye : including the anatomy of the organ / by Carl Stellwag (von Carion) ; translated from the fourth German edition and edited by D.B. St. John Roosa, Charles S. Bull, and Charles E. Hackley. Source: Wellcome Collection.
Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.
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![the flame, may he used, or even a sheet of rough paper fastened in front of the flame, as occasion may require. In case a lamp is used, it will be best to make a round opening in a sheet of paper, cut oval at one end so that it hangs over the shade, and then place it over the glass chimney. Gray paper, especially blotting-paper, is the best material for such shades. Light- colored shades, especially the favorite light green or blue, do not answer the purpose, on ac- count of the intensity of their color in transmitted light. It will be understood that brightly painted or perforated shades are still less desirable. Opaque shades, as, for example, tin ones, are even less useful on account of the contrast which they produce between shaded and illu- minated places. 3. Eye-shades.—These can only be of use when we wish to keep the direct rays of the sun. or of any other intense light from the eye. They avail little or nothing against diffused light. In order to ward this off they must be placed at a very acute angle with the face. Even then the patient looks out of a very dark space, and the contrast produces the same effect as if he looked out of a dark cellar upon the bright sky. The material of which eye-shades are made is not of very great importance. It may be said, however, that shades of coarse gray paper, such as the wrappings of loaf-sugar, fastened on the head by means of a little band, are most to be recommended on account of their flexibility, simplicity, and cheapness. Green taffeta shades, fastened by wire, do not answer as well, since.in direct sunlight they let in a great deal of green light; and the wire presses on the temple, and thus becomes unbearable. The thick pasteboard shades are very unpleasant on account of their stiffness. Eye-shades arc evidently unnecessary in artificial illumination, lamp-shades being sufficient. In direct sunlight, broad-brimmed hats or caps, with large front-pieces, are more easily worn. 4. Veils.—These may be especially used by females and children, whose cases demand that they should be allowed to go out in the fresh air, even when they have irritated eyes. The best are the plain gray or black. Those of a yellow color are not advisable. 5. Protect irr Sjicctctcles.—These are best made of smoke-gray glasses. Green glasses are not advisable, since in a bright light they transmit a very intense and very dark green approaching a yellow, which increases rather than diminishes the irritated condition. Blue glasses are to be preferred to green, as the blue color exerts a leBB severe im- pression upon the retina. Even these do not fully answer the purpose. Deep-blue glasses, as experience teaches us, pain the eye in bright light. Pale-blue glasses, on the other hand, furnish no effective protection. They weaken the light too little. They are only sufficient when we are dealing with a very evanescent condition of irritation, and here protective spec- tacles are nearly superfluous. Smol6-gray glasses, London smoke, weaken the transmitted light very con- siderably, and this naturally in proportion to the depth of their shading. They envelop all the objects in the visual held, as it were, in the twilight el' evening, or of a very dark day ; they allow the objects looked upon to be seen in their natural color, but with very niueh subdued hit* nsity, and on the whole answer fully the pur- pose which may be reasonably expecb <1 from wearing them. Such smoke-gray g] may be obtained in all possible -hades. Those of a light color only are useful. Those glasses whose color in reflect* d light approaches a black, darken the visual field too much. They disaccustom the eyes to the light, and thus render difficult the return to a nor- mal illumination. They also hinder the distinct view even of near objects, and thus often cause the patient to strain his eyes and increase the irritated condition. Ev« i ; om n ay con- vince himself by his own experience of the annoyance of very d< ep shades of It is evident, also, that eyes which require a considerable darkening of the visual field are better](https://iiif.wellcomecollection.org/image/b21002319_0050.jp2/full/800%2C/0/default.jpg)
