This can be caused by several conditions, including vitamin A deficiency, cataracts, and retinal disorders such as retinitis pigmentosa, in which the rod cells in the retina lose their effectiveness. If you find your eyes taking an abnormally long time to adjust to coming into a dark room, get it checked out. Contrast with the much rarer hemeralopia, where vision is normal in dim light but abnormally poor in the bright light of day. From medical Latin, from Greek nuktalōps, night-blind, from nux (in the combining form nukt-), night + alaos, blind + ōps, eye.
Our ability to meet was hindered by her nyctalopia, which made it impossible for her to drive after sunset.