I go temporarily blind once in a while, why?

Firstly the computer screens old or not do not damage your eyes permanently although they certainly give you eye strain. Your eye sight getting worse since you were 13 is fairly typical and relates to your growing as this sort of eye sight problem is due to your eyeball being teh wrong shape and this shows up as you grow. The effect when you walk out into a brighter room is as your pupils adjust to let teh right amount of light in - but like suddenly throwing a torch into someones face , it temporarily blinds them. if your vision has been going down then we can ume you are regularly going to the optician and they will have picked up any eye disease , however do mention this on your next appointment as it is worrying you. If it goes on for more than a minute or two then go to teh optician before but really I think this is a natural reaction and gles /contacts tend to make you more sensitive to sudden changes in light in my experience. I worked on old computer screens for 20 years without their making my vision worse and I've done 72 hour shifts . I also know plenty of other people who have done this so I can ure you that the idea they damage eyes is a myth. they just cause eye strain.