Risley Ophthalmoscope 1887
Risley ophthalmoscope: Risley chose a combination of spherical and cylindric lenses for his model.
He chose the disc from Loring’s model of 1878 with 15 spherical lenses.
On one side of the empty opening there are plus (white) 1-2-3-4-5-6-7 diopters. On the other side, there are minus (red) 1-2-3-4-5-6-7-8 diopters.
He adopted the sliding lens system of Jackson (1885) for the arrangement of the plus cylinder lenses with two lettered slide bars.
Slide A has plus 0.5, 1, 1.5, 2, and 2.5. Slide B has plus 0.25, 3, 4, 5, and 6 diopters.
The cylinder lenses could be combined with any of the the spherical lenses in the disc.
Manufactured and signed by James W. Queen & Co., Philadelphia.
This ophthalmoscope sold for $40.00 USD in 1887. According to the website measuringwealth, this is equivalent to over $1000.00 in 2014 dollars. This high cost at the time might account for the rarity of this ophthalmoscope today.
