Eyes remain dry and not producing tears.

Dryness is not a disease which you can cure by putting lubricating eye drops for few days, while working on smartphone , computer & watching TV for long time without giving importance to the health of eyes. Number of blinking drastically goes down from around 24 per minute to around 8 per minute while working on computer etc causing severe dryness, blurring of vision, headache & increased blinking to compensate dryness .One who works on smartphone etc will have to change &will have to learn how to work on computer for long time without giving any trouble to eyes .One should look away from computer after every 10 minute & should take rest for 10 minutes after every two hours .Every body knows that to become man from monkey took millions of years according to Darwin theory & how you expect that our eyes will adjust to computer in 20 yrs,nature takes its own time, computer development is just 20 yrs history, so you will have to take the help of lubricating eye drops to neutralise the effect of computer etc You should use Systane ultra eye drops 5-6 times & genteal gel at bed time in night. If you are suffering from severe dryness you may take omega 3 fatty acid  one capsule daily( I Dew mega cap)