Brightness and equivalent intensity of intrinsic light.
D003623:Dark Adaptation; D003624:Darkness; D004056:Differential Threshold; D006801:Humans; D008266:Macula Lutea / Q000502:physiology; D008297:Male; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000502:physiology*