Of 42 [male][male] examined ophthalmologically 41 showed no ocular cause for the night-blindness. Of 40 tested for dark adaptation by the Nagel adaptometer, 16 showed mild disturbances and 9 showed no derangement of this function. No evidence of vit. A deficiency could be found. The majority of the 52 had severe psychological disorders. The authors state in conclusion, "The value of dark-adaptation tests for the discovery of night-blind patients and as an indicator of vit. A deficiency appears doubtful. Most cases of night-blindness seen in this country are probably of psychological origin." 55 references.