Your optician or optometrist will be able to diagnose night blindness.
Symptoms of nyctalopia include; weak vision in dim light, difficulty seeing when driving at night and slow reaction time between bright and dim light conditions. Driving at night can be a particular challenge, due to the intermittent presence of headlights and streetlights on the road.
While a condition in it's own right, night blindness may be the result of a related eye problem, listed below.
Astigmatism - With astigmatism, when lighting dims, your pupils dilate to let in more light creating more blur than you would in daylight.
Diabetes - Poor night vision can be an early sign of diabetes. High blood sugar is harmful to the blood vessels and nerves in the eye. A symptom of diabetes is retinopathy, where the back of the eye is gradually damaged. As a result, adjustment to light, such as coming indoors from bright light outside, is slowed.
Cataracts - With cataracts, you'll notice that oncoming headlights cause more glare than before as you'll be more sensitive to light.
Retinitis Pigmentosa - A group of inherited vision disorders which lead to the progressive degeneration of the retina. Deteriorating night vision is often the earliest symptom. Over time, the peripheral (side) vision gradually decreases.