Dry Eye Disease is one of the commonest problems that is diagnosed in an Eye Clinic.  Ironically watering of eyes is one of the symptoms of a "Dry Eyes".  

This brings us to the understanding that "Dry Eye"is essentially a problem of lubrication of the front surface of the eye, called cornea. Cornea is like transparent watch glass and is also the most powerful refractive component of a complex refractive system of human eye. 

Surface of cornea is made smooth and glistening by a thin layer of "Tear Film" that itself is made up of three important components. Mucous the innermost that bridges water repellent corneal surface with a watery middle layer full of nutrients and ions and an oily layer on top to reduce evaporation losses. When we blink the lids pull a small fraction of this fluid from a collection pouch in the lower with capillary action and paints it in uniform coat over the front surface of cornea (much like a paint brush).  The tear film breaks due to evaporation and blink reflex sets in making eyes blink and restore the tear film again.

Dry Eye, therefore, can be due to mechanical problems of the corneal surface or lids, quality of special mucous produced by microscopic glands (post chemical/mechanical damage), lack of watery fluid or over production of oily secretions etc.  Mild inflammation sets in that produces destructive chemicals further worsening the condition.

Reflex tears that are shed due to irritation/noxious fumes/emotional situations are produced by lachrymal glands and do not lubricate the eye surface, in fact they take away some of the precious mucous with their flow.     

Dry Eye Disease is also associated with many auto immune- inflammatory systemic diseases,  that need to be ruled out as well.

Management involves firstly a complete evaluation of the Tear Production and Flow system and tear film stability studies.  Systemic associations of Dry Eye must also be ruled out.  Stay in cool environment temperatures around 24 degree Celsius, Relative Humidity 62%.  Avoid direct flow of air on to the eyes.  Preserve tear film by using protective glasses and use shades out doors.  Cool polarised glass shades cut down glare significantly.  Outflow may be blocked with temporary plugs of varying time periods.  Tear substitutes and tear flow enhancing drops in conjunction with anti-inflammatory drops may be used as per the directives of your doctor.  Some time bandage contact lenses may be required to manage filamentary keratitis.

Dry Eyes are prone to infection which can spread very fast therefore it is important to report immediately if the eyes turn red, develop a discharge or there is sudden aggravation of symptoms.  Formation of filaments can also cause worsening of symptoms.  You can preserve your sight by regular visits to your doctor and report immediately on worsening of symptoms.