Causes of Dry Eye

If your eyes burn, sting or feel gritty by evening, you are in very large company. Dry eye happens when your tears either run short or evaporate too fast - and in the screen age, it has become one of the most common eye complaints of all.

The everyday causes:

• Screens. This is the big one. Normally we blink about 15 times a minute, each blink spreading a fresh tear film. Glued to a screen, that drops to 5-7 blinks a minute. Tears evaporate faster than they are replaced. Phones, laptops and long hours have made dry eye a genuinely modern epidemic.
• Air conditioning and fans. Moving, dry air - AC rooms, car vents, ceiling fans aimed at the face - speeds evaporation.
• Age. Tear production naturally declines with the years; dry eye gets commoner after 50.
• Meibomian gland dysfunction (MGD). The tiny oil glands in the eyelids get blocked, the tear film loses its oily top layer, and tears evaporate too quickly. This "evaporative" type is the majority of dry eye.
• Contact lenses and eye surgery (LASIK and similar), which reduce corneal sensation and tear stability.
• Medicines. Antihistamines, some antidepressants, isotretinoin (for acne), decongestants and certain blood-pressure medicines all dry the eyes.
• Hormonal changes, especially around menopause.
• Vitamin A deficiency - still relevant in India, where poor nutrition can dry the eyes severely.