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.
Severe optic ner-. ve drusen has been correlated with a reduction of. the nerve fiber layer measured by optic coherence. tomography and with the presence of serious visual. field defects. To demonstrate the relationship bet-. ween extensive optic nerve drusen and visual field. defects. Method: A prospective observational study of the. visual fields of a series of 5 patients with severe. optic nerve drusen diagnosed by ultrasonography. Results: Visual field defects of widely differing. severity, from inferior nasal quadrant to severe. hemivisual field defects, were described in each. patient studied. Conclusions: Visual field defects of diverse seve-. rity are common in patients with deep optic nerve. drusen.