One of the most common complaints that brings patients into our clinic is trouble driving at night. Being able to see clearly is very important as vision provides 85% of the information that we need to make safe decisions while driving. While driving during the day, your pupils act like a camera aperture, shrinking down in bright light. This allows light to enter the eye on a straight, uninterrupted path, making things easier to focus and process. Continuing with our camera analogy, your retina is like the film. The retina has photoreceptors called rods and cones that interpret the light and send signals to the brain, which is how we see. Conversely, at night, the pupils are much larger, letting in more light which can be scattered and much more difficult for the rods and cones to decipher. We have many more cones than rods in our retina and in low light situations the rods take over, which means that most of our photoreceptors aren’t as active in the dark. In a nutshell, human eyes are not great for seeing at night, and some degradation in vision is to be expected.
If you’ve gotten to the point where you no longer feel safe or comfortable while driving, it’s time to see your eye doctor to find out if there is something more going on. Many times, the solution is simply a pair of prescription glasses or contacts. Being far-sighted, near-sighted, or having astigmatism can cause oncoming headlights to have a doubling effect or look like there are starbursts and halos around them. In addition to wearing an accurate prescription, an anti-reflective coating on the lenses is a must to cut down on glare. I even recommend this for my patients that have minimal prescriptions to help with nighttime driving and being able to see road signs.
If you’re over the age of 50, then cataracts could be playing a role in diminished night vision. The day we’re born our intraocular lens is crystal clear but as the decades go by, that lens becomes more and more cloudy. Light passing through a cloudy lens will never be as sharp as when it’s passing through a clear lens, especially at night. Cataract surgery replaces the cloudy lens with a brand-new clear lens, which can make a world of difference in the clarity of your vision, day or night.
Lastly, we’ll briefly touch on two conditions that can cause night vision issues that are hereditary in nature. The first is congenital stationary night blindness (CSNB). CSNB is technically a classification for multiple disorders that all have the same thing in common: the condition is present from birth and does not get better or worse as the years go on. The second condition is called retinitis pigmentosa (RP). RP is a disorder that causes difficulty seeing in low light as well as issues with peripheral vision. While there are no cures to date, there are several clinical trials going on in various large cities across the nation that have shown some promise. There are also low vision specialists available in most states that can help patients maximize their remaining functional vision.
Unfortunately, we can’t control how our pupils react to light or change our retinas to be more like nocturnal animals, but we can take advantage of technology and surgical procedures to help with vision in low light. I hope this has been informative and as always, if there are questions or comments, be sure to leave them below.