Effects of Best's Disease

Sight loss can be variable but, like other macular problems, Best's disease threatens central vision in one or both eyes.

Electroretinogram tests, which assess the electrical response of the retina when stimulated by light, can be used to identify people with the problem.

Within 5 identifiable stages, examination of the eye discloses a distinct progression. At first and second stages, there may be little or no effect on sight.

Initially a recording of eye movements and eye position identifies abnormal electrical potential. Eyes will be tested resting or moving in dark and light conditions.

At the second stage (usually between 10-25 years of age), typical yellow spots, sometimes accompanied by material leaking into a space by the retina, can be observed; an observation called "egg-yolk" lesion.

When part of the lesion becomes absorbed this is identified as stage three. Even at this stage there may be little affect on vision.

At the fourth stage, when the "egg-yolk" breaks up, in a process referred to as "scrambled-egg", sight will probably be affected.

The fifth and final stage is when the condition causes the most severe sight loss.