Manual of instructions for the guidance of army surgeons in testing the range and quality of vision of recruits, and in distinguishing the causes of defective vision in soldiers / by T. Longmore.
- Longmore, Sir Thomas, 1816-1895.
- Date:
- [1864]
Licence: Public Domain Mark
Credit: Manual of instructions for the guidance of army surgeons in testing the range and quality of vision of recruits, and in distinguishing the causes of defective vision in soldiers / by T. Longmore. 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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![(].) The Room.—Any ordinary room from which daylight can he excluded by shutters op thick curtains serves for ophthalmoscopic observation. The room should be darkened as completely as pos- sible. It should not contain any bright reflecting objects. There should be only one flame or source of light. The purpose is that all reflected light may be prevented excepting that which is inten- tionally thrown into the fundus of the eye by means of the mir- ror. The room used at the Army Medical School has its ceiling and walls of a dull deep-black colour, all daylight is excluded, and hence, when the patient sits with his back to the flame, there are no reflected rays to fall upon him, the contrast between the darkened face and illuminated fundus is greater, and a less amount of illumination serves to bring distinctly into view the objects to which the observer is directing his attention. A room so darkened, however, is not absolutely necessary. The fundus can be lit up in ordinary daylight by concentrating the light of a lamp upon it, but the objects in it will be less clearly seen. They will make fainter images upon the retina of the observer in proportion as the daylight is brighter, on the same principle that, although the stars transmit the same amount of light to tlie eye by day as by night, they will not be visible at the former time through the greater brightness of the diffused sunlight. The only necessary furniture of the room is a small table on which the light is placed, with seats for the patient and surgeon. (2.) The Flame.—Any moderately bright light that is not flicker- ing will answer the purpose. The more colourless the flame the better. If a gas burner be not available an ordinary argand lamp will well supply its place. If a lamp be not at hand a wax candle will serve the purpose for one who is used to the ophthalmoscope, especially if the room be well darkened. When gas, or an oil lamp, is used, a glass chimney of a blue tint causes the light to be more neutral in colour. The light should have such a support as to place it nearly on the same plane as the patient’s eye. (3.) Mode of tising the Ophthalmoscope.—In describing the manner of manipulating with the instrument it is requisite to note the position of the patient relatively to the oplithalmoscopist, and to explain several inodes of examination to which the instrument may be applied. In the following remarks it is presumed that the examiner uses his right eye for observation of the examined eye.](https://iiif.wellcomecollection.org/image/b22333526_0057.jp2/full/800%2C/0/default.jpg)
