We found that current opaque eye patches can cause 18 problems during visual field testing.
Most unusual was repetitive blackout of vision in the tested eye from the difference in illumination between the two eyes, called the Ganzfeld effect. When this blackout occurs, the patient has difficulty seeing the smaller targets, which causes spot retesting by the machine and prolongs the test. One can see this fading of vision by staring at a brightly lit wall with both eyes open from a distance of 20 inches for 15 seconds. When (Read more...)