Causes of Dry Eye 

Dry eyes may occur when your tears are unable to provide sufficient lubrication to your eyes. This condition may take place if your eyes are not producing tears in sufficient volume, or if the produced tears are of a poor quality. It is best to see an eye surgeon if have persistent symptoms of dry eyes, including tired, irritated, red,or painful eyes.

Lack of adequate production of tears is the key cause behind dry eyes. Your tears are a complex blend of water, mucus, and fatty oils. This combination helps keep the eye surface clear and smooth, and it also provides protection to the eyes against infection.

In some cases, the tear production may not have reduced, but the tear evaporation may have increased, or there could be an imbalance in the composition of tears. These issues may also cause dry eyes.

When lack of adequate production of tears causes dry eyes, the condition is clinically known as kerato-conjunctivitis sicca. Common causes of this condition include:

• Aging effects
• Some types of health conditions, such as rheumatoid arthritis, diabetes, scleroderma, lupus, thyroid disorders, Sjogren’s syndrome, and deficiency of vitamin A
• Some types of medications, such as decongestants, antihistamines, antidepressants, hormone replacement therapy, and drugs for acne, hypertension,
• Parkinson’s disease, and birth control
• Laser eye surgery (resulting in temporary dry eye symptoms)
• Damage to the tear glands due to radiation or inflammation 

• Dry air, wind, or smoke
• Infrequent blinking, which usually occurs when you are using the eyes with concentration for prolonged periods, such as when working on a computer, reading, or driving
• Eyelid problems, such as entropion (inward turning of the eyelids) or ectropion (outward turning of the eyelids)  

The tear film is made up of three layers: water, mucus and oil. If any of these layers develops a problem, it can cause dry eye. For instance, the oil film produced by the glands on the border of the eyelids may get clogged. This may occur more commonly in people whose eyelid edges are inflamed (blepharitis), or they suffer from skin disorders such as rosacea.

The following factors increase your risk of developing dry eyes: 

• Over 50 years of age: Dry eyes are more common after 50 because tear production gradually diminishes as you age.
• Female gender: Women are more commonly affected by dry eyes, particularly when they undergo hormonal changes.
• Vitamin A deficiency: People who eat a diet that is low in vitamin A may have a higher risk of developing dry eyes.
• Regular use of contact lenses