Dry Eyes are caused by any kind of deficiency of the thin tear film on the eye that guarantees its moisture.
The causes of a tear film disorder are:
a reduced production of tear fluid by the glands (mostly an initial lack of oil) or
an altered eyelid blink, which does no longer spread the tears into a thin and even tear film
Tear deficiency and blinking disorder can reinforce each other.
Various risk factors can contribute to developing or worsening of dry eyes:
Internal risk factors lie in the body itself and can hardly be influenced.
External risk factors mostly consist of drying environmental influences and can be partially improved.
=> here is some advice on how to avoid the most prevalent risk factors