Dezeng Retinoscope 1912
De Zeng Retinoscope was called Ideal Electric Retinoscope 280.
It is marked De Zeng and patented Aug 25 ’03. (see image)
It has a battery holding handle. It it turned on by depressing the silver color tab on the side.
There is no slide mechanism to change the focus. There are the letters DEZ and ENG on either side of the mirror.
These are described as illuminated letters because there are slits in the tube next to the bulb so that light can spill out and shine on these white on black letters.