Transient lumanopia: the invisibility of flicker in early dark adaptation.

Flicker thresholds for brief white (5-arcmin, 16-18-Hz) foveal flicker bursts can rise for at least 1 s after a steady white adapting field is extinguished. We call this anomalous loss of sensitivity in early dark adaptation lumanopia by analogy with dyschromatopsia, a similar anomaly of the hue pathways. Lumanopia is greatest at 400 Td. Flicker thresholds for 10-12 Hz flicker bursts do not show lumanopia. The temporal-frequency dependence of lumanopia is specific to early dark adaptation, as flicker thresholds vary little from 10 to 18 Hz after steady light or dark adaptation. Lumanopia has implications for models of retinal gain controls.