The ophthalmoscope : a manual for students / by Gustavus Hartridge.

  • Gustavus Hartridge
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: The ophthalmoscope : a manual for students / by Gustavus Hartridge. Source: Wellcome Collection.

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    vessels have a foreshortened appearance, as well as being wavy; the detaclmient and the vessels on it will also be found to be very hypermetropic, that is sup- posing the details of the disc are seen clearly without a convex glass behind the ophthalmoscope, and that the weakest convex glass blurs these details: the detached portion of the retina, or if it be transparent, then the vessels on it, may be seen with a strong con- vex glass; the more forward the retina, the higher the glass through which it can be seen. If the strongest glass be thus found out, we may estimate the distance between the detachment and the sclera; for 3 D. equals 1 mm., so that if the case in question could be seen with a convex 12 D., while the disc was emmetropic, then we should know that this distance was 4 mm. Detachments are, however, most frequently met with in myopes, so that a concave glass would be necessary to see the details of the disc; and yet perhaps the detachment may be clearly seen with a convex glass, the difference between the weakest concave glass with which the disc can be clearly seen and the highest convex glass with which the par- ticular vessel can be seen, will give us the measure- ment we require. In many cases a part of the detachment is trans- parent while a part has become opaque; sometimes a rent can be detected, so that the fluid in front and behind the detachment being in direct communication, the retina can float about with every movement of the eye. The edges of the torn retina will be found turned in towards the vitreous.
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