[Congenital large field color vision defects].

To investigate changes in the way of seeing colors due to expansion of the visual angle in patients with congenital color vision defects, an anomaloscope which can alter the visual angle to 2 degrees, 6 degrees, 10 degrees, 15 degrees and 20 degrees was prepared using three colored light emission diodes, and 28 patients with congenital color vision defects were examined. The results showed that the patients could be categorized into two groups: one with no change in the equation range and one in which the equation range was contracted. Contraction of the equation range was marked when the visual angle was 10 degrees or more.