Knauer’s ophthalmoscope 1890
This model has a main disc with 9 concave lenses: 1-2-3-4-5-6-7-8-9 diopters and an empty opening.
The combination disc has 5 lenses: concave 10-20-30 and convex 10 and 20 diopters plus an empty opening.
Lens values of – 1.0 to -39.0 and convex +1.0 to +20.0 can be achieved in one diopter steps. The lens powers can be read directly.
With the advancement of the -0.5 concave lens, the lens power can be increased or reduced by one half diopter. The instrument is supplied with concave and plane mirrors which can be angled and changed.
An convex lens of 36 mm diameter and +13 diopters of power (same as a trial lens of the day) plus a handle is included.
