Smart phones can be hazardous for eyes

Youngsters are so obsessed with smartphones these days that they end up spending long time on these devices.But most of them don't know how damaging it can be for their eye sight.Eyes fixed with screen thrust very close,its magnifying image does affect the eyes and as a result lot of them get to wear spectacles at a very young age.
Earlier there were only TV,then came computers and non we have hand held devices.Nobody denies there utility but excessive use/frivolous use needs to be avoided.