I see patients with night vision problems quite often at my practice. Usually, what brings them in is vision problems while driving at night. Vision problems related to driving at night — such as seeing halos around lights or seeing lines streaking out from lights at night—can be very disorienting, particularly if you’re driving in an unfamiliar place or in a lot of traffic. It can be dangerous too!
You may feel like your vision worsens at night. This is actually true, to a certain extent. Your retina has two types of photoreceptor cells embedded in it: Rods and cones. Cones make up most of your central vision and provide clearer vision than rods, but require good light. At night or in poor lighting, your rods take over. However, unlike cones, rods are more peripherally located in your retina, so they do not provide the same clarity of vision as cones do, but they don’t need as much light, so they provide you with your night vision. Technically, your vision doesn’t really get worse; if you turn the lights on, you’ll see like you usually do, but you’re using a different part of your retina in low light situations that doesn’t have the same clarity as your central vision.
What Causes Loss of Night Vision? Outside of the difference between rods and cones, poor night vision can be caused by many factors. The most common factor is typically uncorrected or under-corrected vision. Patients that are nearsighted (myopic) or have astigmatism tend to have the most problems with bad night vision. Often a simple update to their prescription fixes the issue! Tired, sore, uncorrected eyes can blur at any time of the day. In many cases, it’s not even a prescription change, but a lens change, that fixes the problem. It’s difficult to see through old, scratched up lenses even if the prescription is correct!
Another factor that can cause trouble seeing at night is cataracts. Cataracts usually affect people over the age of 60. (If you’re on the younger side of things, your poor night vision is probably not cataract related). If you’re over 60 and having trouble with night vision, it’s a good idea to have your eye care professional check you out not only for possible glasses but also for cataracts.
If you do have cataracts, in moderate to severe cases, glasses or contact lenses probably won’t be sufficient to get you seeing well enough to drive at night, or maybe even during the day. In these instances, it’s best to get a referral to a cataract surgeon for an assessment. If your cataracts are indeed ready to be removed, you very likely will be shocked by how much better you see after the surgery! It’s eye-opening, pun intended.
How do you know if you have night blindness? Some people who have trouble seeing at night may go as far as to say they have “night blindness”. Often, as mentioned above, glasses, contacts or cataract surgery can fix this. In the case of “true” night blindness, a patient typically has corneal or retinal problems. If the cornea is scarred or swollen, lights can look streaky or hazy. In the case of retinal diseases, a person may actually be missing parts of their retina or have had damage to other parts of their retina or to their rods. As mentioned earlier, the rods help us to see at night. Unfortunately, in these cases there may not be much hope for improved night vision, although there are some options available, such as low vision aids, that may help.
While that last paragraph may sound scary, thankfully, most night vision issues are generally easy to fix! If you’re having trouble seeing at night or feel uncomfortable driving at night, be sure to mention this to your eye care provider. A simple glasses or contact lens prescription may be just the ticket to clearer, more comfortable vision at night!