Tears:
Tears are made up of three main layers (oily, aqueous, and mucous):

• The outer oily layer: It makes the surface of the tears in the eye smooth, and prevents tears from drying too quickly.
• The middle aqueous layer: It forms most of what we see with tears and is responsible for cleaning the eye's hydration and protecting the cornea.
• The inner mucous layer: It is the one that covers the white of the eye and the inside of the eyelids, and is responsible for spreading the aqueous layer on the surface of the eye to keep it moist and without it, tears will not stick to the eye.

Dry Eye:
It is a common and often chronic problem that occurs when there is little tear production in the eye or when tears are unable to work properly.

Causes:
Tear production decreases with age due to hormonal changes.
Here are some other causes of dry eyes:

• Low quality of tears produced by the eye, which changes their composition and leads to a defect in their function (such as: speed of their evaporation or not spreading evenly over the cornea).
• Certain diseases (e.g.: rheumatoid arthritis, Sjogren's syndrome, thyroid disease, lupus).
• Blepharitis.
• Being in a place with smoke, wind, or a very dry climate.
• Looking at a computer screen for a long time, reading and other activities that reduce eye blinking.
• Use of contact lenses for prolonged times
• Performing refractive eye surgery (e.g.: LASIK).
• Taking certain medications (such as: diuretics, treatment of heart problems or high blood pressure, allergy and cold medications, antidepressants, and heartburn medications).

Risk factors:
Factors that may contribute to dry eye include:

• Getting advanced in age and exceeding the age of 65 years.
• Gender, as women are more susceptible to infection; As a result of exposure to changes in hormones (menopause).
• Medical conditions (such as: rheumatoid arthritis, diabetes, and thyroid problems).
• Eyelid inflammation.
• Taking medications (such as: antihistamines, decongestants, blood pressure medications, and antidepressants).
• Exposure to wind, dust, dry air or smoke.
• Sitting in front of screens for long hours without blinking regularly.
• Long-term use of contact lenses.
• Undergoing an eye operation such as vision correction (LASIK).

Symptoms:

• Burning eyes.
• Blurred vision, especially when reading
• Feeling that something is inside the eye that excites it.
• Strands of mucus in or around the eye.
• Eye redness or irritation.
• Pain when wearing contact lenses.
• Sensitivity to light

When to see a doctor:
When feeling a symptom of dry eye or feeling a difference in vision.
 
Treatment:
Treatment for dry eyes depends on the cause. Some medications are used to relieve symptoms, including:

• Using artificial tears, which are eye drops with a solution similar to eye tears, and they can be bought without a prescription.
• The doctor may block the tear ducts in the eye to preserve natural tears as long as possible, either with silicone plugs or surgery if necessary.
• The doctor may prescribe medications to increase tear production.
• Treating blepharitis or eye inflammation using some drops or ointments.
• When severe irritation and itching occur in the eye, the doctor may prescribe medicated drops or ointment to calm it down. Warm compresses can be applied to the eye or eyelids massage to calm the eye.

Prevention:

• Try not to use a hair dryer if possible.
• Avoid very warm rooms.
• Use humidifiers, especially in winter.
• Protect your eyes from dry winds by wearing special glasses.
• Use tear ointment or thick eye drops just before going to bed.
• Blink regularly when reading or looking at a computer screen for long periods of time.
• Avoid dehydration by drinking plenty of water (8 to 10 glasses) each day.
• Avoid environments that are drier than usual (e.g.: deserts and places at high altitudes).
• Wear sunglasses when going outside during the day.
• Get enough sleep 7-8 hours a night.