[Subjective contrast evaluation by visually handicapped patients].

Personal optical and electronic devices are helpful to people with binocular vision of less than 0.3 or a substantially impaired visual field. Striking brightness and color contrast may help patients to orient themselves outdoors. This is particularly true for patients with age-related macular degeneration who have diminished contrast sensitivity as evaluated by the Vistech test and the low-contrast sensitivity test. In this study, the desired level or color combination of contrasts was assessed subjectively by a scaled estimate. The patients were required to assess a sample of 79 black-and-white and color contrasts according to a five-point scale comprising the ratings "much too low", "low", "optimal", "high", "much too high". The visual fields (outfield, infield) were either colorless or contained the colors yellow, green, red, purple or blue. The study involved 59 patients with age-related macular degeneration. Ninety percent of the patients were over 65 years old. There were twice as many women as men. The control group population consisted of 43 emmetropic subjects. In black or white infields on a colorless background (light gray to dark gray), a slight preference for positive (infield lighter than the background) contrast situations was found. The optimal contrasts were in the range of [K[ > 0.91. When colored infields were presented on a colorless background, the light infield colors yellow and green were preferred. The optimal contrast level was found to be [K[ > 0.85. Similarly, when colorless and colored infields were presented, light infield colors (white, yellow, green) on a dark background (purple, blue) were preferred. In selecting contrasts, subjects with impaired vision because of age-related macular degeneration preferred positive contrasts, i.e., mainly white, yellow and green on a colored or colorless background. These results provide information that can be used in designing orientation aids, e.g., road striping and lines, edges of stairs, handrails, timetables, etc. Conflicts of interest with emmetropic subjects is not to be expected. Subjects in the control group, while preferring similar contrasts, were ready to accept a wider range than the partially sighted.