MEDI-LEARN

Book of Color Charts, Velhagen-type

These are color charts with standardized color pictures used in eye care and diagnosis of color vision defects, e.g., red-green color vision deficiency.

• tests for red-green defect
• in book format, with 23 tables and transparency gray test

Method

Numbers and letters appear over a patterned background in a variety of contrasting colors. While the individual color values of the figures differ from the background, they share the same degree of brightness. That means the pictures can only be recognized by their color and not by how strongly the reflect the light.

If color vision deficiency exists in the patient, individual figures will not be recognized or else they are misperceived as different kinds of objects because of the way the patterns are designed to mislead.