Best disease is an inherited form of juvenile macular degeneration characterized by a loss of central vision.
Best disease affects the macula, the central part of the retina responsible for fine visual detail and color perception. Although the age of onset for those with Best disease can vary, it is usually diagnosed during childhood or adolescence. In the initial stages, a bright yellow cyst (fluid-filled sac) forms under the retinal pigment epithelium (RPE) beneath the macula. Upon examination, the cyst looks like a sunny-side-up egg. Despite the presence of the cyst, visual acuity may remain normal or near normal for many years. Peripheral (side) vision usually remains unaffected.
In many individuals with Best disease, the cyst eventually ruptures. Fluid and yellow deposits from the ruptured cyst spread throughout the macula. At this point the macula has a scrambled egg appearance. Once the cyst ruptures, the macula and the underlying RPE begin to atrophy (degenerate) causing further vision loss. As a result, central vision tends to deteriorate later in life. However, Best disease does not always affect both eyes equally. Many individuals retain useful central vision in one eye.
For information on another juvenile macular degeneration, see Stargardt Disease, since Best disease and Stargardt disease are juvenile forms of macular degeneration.