Value is the dimension of lightness/darkness. In terms of a spectral definition of color, value describes the overall intensity or strength of the light. If hue can be thought of as a dimension going around a wheel, then value is a linear axis running through the middle of the wheel, as seen below:
Drusen are tiny yellow or white deposits in a layer of the retina called Bruchs membrane. They are the most common early sign of dry age-related macular degeneration. Drusen are made up of lipids, a type of fatty protein. They may be the result of a failure of the eye to dispose of waste products that are produced when the photoreceptors of the eye drop off older parts of the cell. There are several types of drusen with different levels of risk.
Classification [edit]. Drusen are associated with aging and macular degeneration are distinct from another clinical entity, optic disc drusen, which is present on the optic nerve head.Both age-related drusen and optic disc drusen can be observed by ophthalmoscopy.hether drusen promote AMD or are symptomatic of an underlying process that causes both drusen and AMD is not known, but they are indicators of increased risk of the complications of AMD. 'Hard drusen' may coalesce into 'soft drusen' which is a manifestation of macular degeneration.