A fine retinoscope by London based Angus MacNab (c.1876-1914) with a detachable ivory handle in its own silk and velvet case leather case.
The calibrations around the outside are the axis of the astigmatism. The light would be situated next to the patient shining towards the examiner and reflected from the mirror or glass into the patient’s eye.
Retinoscopes were used at arms length to estimate the patient’s refraction by measuring the rays of light as they are reflected by the retina. Retinoscopy is also known as skiametry, which indicates that shadows (reflexes) are being observed. Another early term for retinoscopy was ‘optometric ophthalmoscopy’. The first man to observe a linear fundus reflex was Sir William Bowman in 1859, using a Helmholtz ophthalmoscope and there remained some overlap between the use of retinoscopes and ophthalmoscopes.