Night blindness (also known as nyctalopia) is a condition in which someone has trouble seeing in dim light or darkness. This trouble can include a need for the eyes to adjust for an unusually long amount of time when going from light to dark places, like going into a darkened movie theater.
The problem is centered in your retina’s rod cells. These cells function as photoreceptors that convert light rays into electrical signals, creating what brain interprets as images. You have two kinds of photoreceptors in your eyes: rod cells and cone cells.
Rod cells specialize in movement and adaptation to darkness/light while cone cells specialize in distinguishing colors. When your rod cells suffer damage, that’s when night blindness can set in. This could be assessed by the regular eye exams.
Damage to the rod cells can come in many forms. Night blindness itself is actually a symptom of a number of common vision problems rather than a condition in and of itself. Some of those conditions are:
- Cataracts – A condition in which the lens of the eye becomes cloudy, resulting in blurry or distorted vision
- Myopia – Nearsightedness, where close-up objects are clear but far-away objects are blurry
- Glaucoma – Medications used to treat glaucoma can cause night blindness
- Vitamin A deficiency – A lack of pigments needed for your eyes’ photoreceptors to work correctly
- Retinitis pigmentosa – A disease in which there is damage in the retina caused by genetic defects
- Usher syndrome – A genetic condition involving hearing loss and retinitis pigmentosa
Symptoms of night blindness include:
- Abnormal trouble adapting to the dark while driving at night
- Blurry vision when driving in the dark
- Difficulty seeing in places with dim lighting, like your house or a movie theater
- Excessive squinting at night
- Trouble adjusting from bright areas to darker ones
- Inability to see pedestrians walking at night
- Reduced contrast sensitivity
Treatments for night blindness vary depending on the cause and can be determined by the eye doctor. If it is cataracts, eye surgery might be the best solution. If it’s myopia, maybe you need a new prescription.
If it’s medications or a vitamin A deficiency, a new medication or supplement may be in order. If it’s retinitis pigmentosa or usher syndrome, your eye doctor can suggest treatment options for your particular symptoms those might include special eyeglasses for vision rehabilitation. As well in rare cases this could be replaced by the contact lens.
One of the biggest challenges to those with night blindness is driving at night. If you have worked with your VSP® network doctor to arrive at an effective solution to your night blindness and have been cleared by your primary physician to drive at night, here are a few ways you can make that activity easier:
- Keep your headlights and windshield clean to emit as much light as possible from your headlights and to decrease the amount of glare on your windshield caused by light reflecting off of dirt or debris as american optometrics suggest.
- Get your headlights aligned so they are illuminating as much of the road as possible (as opposed to shining straight at cars in front of you).
- Adjust your rearview mirror. Some rearview mirrors have a setting made for driving at night to reduce the brightness of lights behind you. Check to see if your mirror allows for this adjustment. If it doesn’t, consider investing in one that does.
- Focus on the lines in the middle of the road and other road markers. The key here is not looking directly at the lights on the roads but focusing on the areas onto which they are shining, such as the lines on the road.
This is blog post by Stephen L. Glasser, O.D., F.A.A.O., an optometrist in Washington, DC.