Eperon style ophthalmoscope
This ophthalmoscope looks like the one by Eperon except that the hole in the mirror is circular instead of rectangular as was described in the original Eperon ophthalmoscope.
From The Ophthalmoscope by Alfred Schett:
“A publication of Eperon’s ophthalmoscope is not known. It probably was developed in the early years of his work at the ophthalmology clinic in Lausanne. The plane mirror, uncoated in the center, has a rectangular opening instead of the usual circle. The long axis is arranged vertically. To the side there is a clip fastened with two swivel joints. With this the convex lens of 2.5 diopters can be swung to the side in front of, or behind the mirror.
The plane mirror alone was intended for skiascopy and illumination of the transparent media of the eye. With the lens behind the mirror the
instrument served for the examination of intraocular clouding. With the lens in front of the mirror one achieved the optical working of a concave mirror and a slight magnification of the inverted image. An inverting lens was included.
Manufacturer: Pfister and Streit, workshop for precision machinists in Bern. Now Haag-Streit AG.”