If you grew up in the 20th century, you heard both of these warnings repeatedly. Don't read in dim light — you'll ruin your eyes. Don't sit too close to the TV — you'll go blind. They were delivered with parental authority and complete confidence. Neither has any basis in ophthalmology.
Quick answer
Reading in dim light can make your eyes tired, but it does not permanently damage them. Sitting close to a modern TV does not damage eyesight either. If a child consistently sits very close to screens or books, it may be a sign they need an eye exam.
Reading in dim light
The American Academy of Ophthalmology is unambiguous on this: reading in low light does not damage your eyes. It can cause eye strain — a temporary condition involving tired, uncomfortable eyes, difficulty focusing, and sometimes headache — because your eye muscles work harder to maintain focus in poor contrast conditions. Eye strain resolves with rest. It leaves no lasting damage.
The experience of eye strain after reading in dim conditions probably gave rise to the myth. Parents observed children squinting and complaining of sore eyes after reading by flashlight under the covers, concluded damage was occurring, and issued warnings. The association was real; the causal mechanism they assumed was not.
Ophthalmologists describe the relationship between lighting and eye health as analogous to lifting a heavy object while tired: your muscles fatigue, they may be sore afterward, but no structural damage occurs.
Sitting close to the TV
The television myth has a specific origin. In 1967, General Electric recalled a line of color televisions that had been found to emit X-ray radiation at levels exceeding federal safety guidelines — roughly 100,000 units were recalled or modified. The US Surgeon General issued a warning advising people not to sit closer than 6 feet from color televisions until the issue was resolved.
The recall was legitimate. The radiation problem was real and was fixed. But the resulting warning — "don't sit too close to the TV" — became generalized cultural advice that outlasted the specific technical problem that prompted it by decades. Modern televisions emit no meaningful radiation of any kind.
For children who sit very close to screens, ophthalmologists note that this is often a symptom of myopia (nearsightedness) rather than a cause. A child sitting close to the TV can't see it clearly from further away. The appropriate response is an eye examination, not a rule about distance.
What actually does affect eyesight
Myopia and near work. There is genuine evidence that time spent on close work — reading, screens — is associated with increasing rates of myopia, particularly in children. The mechanism appears to involve both near work itself and, critically, reduced time spent outdoors. Outdoor light exposure appears to be protective against myopia development, possibly because bright light causes the pupil to constrict, providing sharper focus across a range of distances. Studies in East Asia, where myopia rates have increased dramatically alongside intensive academic work and reduced outdoor time, provide some of the strongest evidence for this relationship.
UV exposure. Cumulative sun exposure is associated with cataract development and macular degeneration over decades. Sunglasses with UV protection are one of the few genuinely evidence-backed interventions for long-term eye health.
Diabetes. Diabetic retinopathy is a leading cause of blindness in working-age adults. Blood sugar management is more consequential for vision than any amount of reading lighting.
The pattern
Both the dim light myth and the TV distance myth follow a familiar structure: a real but temporary symptom (eye strain, squinting) is interpreted as permanent damage, a parental warning is issued, the warning is passed down through generations, and the original reasoning — flawed in the dim light case, outdated in the TV case — is never revisited.
The warnings feel protective. They're also wrong. Your eyes are more resilient than the folklore suggests.
For more everyday health myths, read eight glasses of water, the five-second rule, and sugar and hyperactivity.