Dry eye can be caused by any factor that interferes with the normal functioning of the tear film. For example:

• Ageing the prevalence of dry eye increases with age. Increasing age is associated with abnormal lipid production, which can give rise to evaporative dry eye. Two to three times more women than men are affected.
  
  

• Climate and other environmental factors modern living (air conditioning, central heating, air travel and pollution) and the outdoor life (wind, heat, sun exposure and high altitudes) can all change the prevailing atmosphere and have a role in dry eye.
  
  

• Systemic Disease conditions in which dry eye occurs include rheumatoid arthritis, Parkinson’s disease, diabetes and auto-immune diseases.
  
  

• Eye Diseases affecting the meibomian glands and eyelid conditions these can all contribute to tear film instability and cause dry eye.
  
  

• Medications the side effects of many therapeutic treatments (for example, anti-allergics (antihistamines), HRT and some sleeping pills) include dry eye.
  
  

• Low blink rate blinking spreads tears over the surface of the eye and interference with this (reading, computer use, watching television etc) can result in dry eye.
  
  

• Contact lens wear contact lenses physically interfere with the tear film and rub against the conjunctiva under the eyelids.
  
  

• Eye surgery particularly refractive correction.