3 ms·
If exposure to bright light is the primary cause of most near-sightedness, than not seeing the sun would be beneficial. I don´t get it, typo?
by exceptione 4y ago
If exposure to bright light is the primary cause of most near-sightedness, than not seeing the sun would be beneficial. I don´t get it, typo?
- dan-robertson 4y agoYeah typo. The theory is that eyes change shape over time (I think starting out longsighted) and at some point a hormone is released to stop this changing. It is released when (a) the eyes are typically around the middle of their focal range (ie looking at middle-distance things is done with relaxed eyes) and (b) there is a lot of light. Without the second condition the shape of the eyes will continue to change and then you get myopia.
- derefr 4y agoSee also: metabolic bone disease in lizards. Also caused by a lack of light — in their case, near-UV light. (My understanding is that the thing changing the shape of the eye over time is the development of the orbital socket bones — so nearsightedness and MBD could have more in common than it seems.)
- corrral 4y agoYeah, typo, too late to edit. Insufficient exposure to bright light during key, early years while the eye is developing was found to increase risk so much that it's practically all that matters, at least over a population (I'm sure some unlucky people get it for other reasons, like most things)