Image Based Question – 73349

Identify the  instrument:

A. Maddox rod

B. Maddox wing

C. Maddox glass

D. Red glasse

Correct Answer » A Explanation

Answer. A. Maddox rod

• The Maddox rod test can be used to subjectively detect and measure a latent, manifest, horizontal or vertical strabismus for near and distance.
• The test is based on the principle of diplopic projection
• The Maddox rod is a handheld instrument composed of red parallel plano convex cylinder lens, which refracts light rays so that a point source of light is seen as a line or streak of light.
• Due to the optical properties, the streak of light is seen perpendicular to the axis of the cylinder.

The Maddox rod test should be used in cases of:

• Small to moderate (i.e..<25pd) vertical deviations where there is simultaneous perception and normal retinal correspondence (NRC)
• Decompensated phorias.
• Acquired strabismus (rather than congenital or early onset)