Sir: Medical experts have urged smart phone users to limit excessive usage as this may lead to damage to eyes in the long term because of the many hours spent staring at screens. As much as we depend on our mobile device for responding to E-mails, reading headline news and posting status updates on Facebook, our smartphone may be causing us some vision problems. Moreover, health experts say that long term blue light exposure may led to juvenile macular degeneration and soon a point may come when the eyes cannot see real colors properly. Short term and immediate effects include the formation of red eye, lack of concentration and sleep deprivation. Experts suggest less than two hours screening time for children under the age of eight. Parents must be careful about this. Qadeer Suchan Turbat Published in Daily Times, January 13th 2018.