The<unk>  measures the size of heterophorias (latent deviations) and small heterotropias (manifest deviations) at near when normal retinal correspondence (NRC) is present. It is especially helpful when patients present with symptoms of diplopia (double vision) with no apparent cause. Unsuspected torsional deviations may also be revealed where there are no symptoms present. It is a quick and convenient method of measuring the size of a deviation and is generally used in association with a number of other tests before a full diagnosis is determined. The scale card of the<unk> , depicting the horizontal, vertical, torsional scales and their respective arrows.
Maddox wing
Cramp-ring
Cabot rings
Racquet nail
Pincer nail
Perryville Tree engravings
Surfer's knots
Kerley lines