Simple early ophthalmoscope
Simple early ophthalmoscope consists of a plane mirror on a long handle. There is a hole in the middle for the examiner to look through.
This simple early opthalmoscope was used with a condensing lens (usually a lens of +13.00 to +20.00 diopters of power) to view the back of the living human eye.
The light source was a candle or a gas lamp. This would reflect off the mirror into the patient’s pupil to illuminate the interior of the eye.
It was later discovered that when the mirror was moved, the light would move within the eye to produce a sort of shadow effect.
Depending on the person’s refractive error this movement could be neutralized by the used of various powered lenses placed in the path of the light.
This was how retinoscopy was discovered. So, this same type of simple ophthalmoscope also served as the earliest retinoscope.
This is signed Reid of Philadelphia on the back and refers to J.E.Reid Instrument company which existed in Philadelphia from at least 1880 to 1925. (see ad in images)
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