A simple variable prism with a linear scale.
OBJECTIVE
To build a simple, low cost, variable-power prism with a linear scale.


METHODS
A sliding lens system, using the prismatic effect of ophthalmic lenses, was constructed.


RESULTS
The system functions well at low powers using conventional curved form ophthalmic lenses.


CONCLUSIONS
The sliding lens variable prism is a useful alternative to the conventional rotating variable-power prism.
Walsh
Glyn
G
Division of Vision Sciences, Glasgow Caledonian University, Glasgow, Scotland, United Kingdom.
Rafferty
Peter
P
Pearce
E Ian
EI
D004867:Equipment Design; D005139:Eyeglasses; D006801:Humans; D012030:Refractive Errors / Q000628:therapy