HOW THE EYE WORKS UNDER LOW LIGHT
Our eyes react to the amount of light in our environment. As the amount of light is reduced, the pupils enlarge to allow more light to reach the retina at the back of the eye in an effort to keep vision clear and effective in less than ideal conditions. Reading in low light decreases the ability of the eyes to focus clearly, which causes them to become tired. Many people also blink less frequently under low light, which can cause temporary dryness. Conversely, in bright light, pupils shrink in order to decrease the amount of light reaching the retina. The retina then transmits the light and visual information to the brain, allowing us to see.
THE EFFECTS OF READING IN LOW LIGHT
Your mom was only partially right all those times she caught you reading in low light and chastised you by saying, “You’ll ruin your vision reading like that! Turn on a light!” The good news is that even if you do suffer ill effects from reading or other activities in low light, there are no long-term or permanent effects to the eyes merely due to the amount of light.
While there are no long-term effects on the eyes from reading in low-light, some patients do experience headaches or eyestrain. Eyestrain is a temporary condition and should resolve anywhere from a few minutes to half an hour after you finish reading or move to an area with more available light.
SIGNS OF EYESTRAIN
Even if it wasn’t due to reading without adequate light, you have likely experienced eyestrain at some point in your life. Eyestrain is an increasingly common, but minor, condition that affects more and more patients as technology and spending long amounts of time in front of digital screens and devices becomes part our daily lives. Typical symptoms include burning or itching eyes, dry eyes, or tired eyes. Some patients may also experience minor headaches with eyestrain.
PREVENTING AND TREATING EYESTRAIN
Although eyestrain isn’t permanent, it can be uncomfortable. The first line of defense against eyestrain is to have regular vision screening examinations to ensure that your eyes are healthy and also to monitor for vision changes. Such eye exams will also determine if you need glasses or contacts, or changes to current prescriptions. Wearing your glasses or contacts as directed and reading under better lighting conditions should resolve most of your eyestrain symptoms. Looking up or away from your reading material every 20 minutes or so for several seconds at a minimum will also give your eyes a mini-break while reading. If you still suffer from eyestrain and your eye doctor has declared your eyes healthy, you may be prescribed lubricating eye drops to help with the irritation that typically accompanies eyestrain.
WHAT IF YOUR SYMPTOMS DON’T GO AWAY?
It is important to recognize the difference between a normal headache or eyestrain after reading in low light compared to those symptoms indicating more serious problems. If you experience sudden changes in the vision of one or both eyes, double or blurred vision, head pain that is not like a typical headache or that is severe, seek immediate medical attention. The same is true if these symptoms are accompanied by speech changes, weakness on one side of the body or in one extremity, slurred speech, a facial droop, or changes in sensation. These are serious symptoms and should be treated as a medical emergency requiring a visit to the nearest emergency department.