Dry Eyes: Why It Happens And What Can Be Done?

Eyes convey what words may fail to. They display different kinds of emotions predominantly via tears - the secret weapon women use to win wars. Tears do much more than show our emotions - be it sadness, anger, or joy. Tears help us see clearly and wash debris from our eyes. Crying for emotional reasons makes you feel better. But there are physical reasons, too, for which you cry, like if you've got dirt in your eye. Crying also happens for physical reasons to deliver nutrients and wash out stress-related toxins. But have you wondered what would happen if one day, you are no longer able to shed tears? What if your eye runs dry?

Dry eye syndrome

Dry eyes, also known as dry eye disease, dry eye syndrome, and keratoconjunctivitis sicca (KCS) are one of the most common reasons for a visit to an eye doctor. This condition affects a significant number of people. 

The cause of this condition may be anatomical or systemic. It is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film and accompanied by ocular symptoms like tear film instability, hyperosmolarity, and ocular surface inflammation and damage.

In this disease, tears are not able to provide adequate lubrication to the eyes. Dry eyes may occur if you don't produce enough tears or if you produce tears of poor quality. Dry eyes make you feel uncomfortable.

Our eyes are dependent on the presence of a tear film for constant moisture and lubrication to maintain vision and comfort. The tear film is approximately 2 to 5 µm thick over the cornea and is composed of three main components,

• Lipid (outside layer) - It makes the tear surface smooth and keeps tears from drying up too quickly. This layer is made in the eye's meibomian glands.
• Aqueous (middle layer) - It makes up most of what we see as tears. This layer cleans the eye, washing away particles that do not belong in the eye.  This layer comes from the lacrimal glands in the eyelids.
• Mucin (inner layer) - This helps spread the watery layer over the eye's surface, keeping it moist. Without mucus, tears would not stick to the eye. Mucus is made in the conjunctiva. This is the clear tissue covering the white of your eye and inside your eyelids.

Normally, our eyes constantly make tears stay moist. But, sometimes the eyes don't make enough tears or something affects one or more layers of the tear film. In those cases, we end up with dry eyes.

1. Types of dry eye diseases

Dry eye disease has traditionally been classified into two categories: aqueous deficient and evaporative. These two categories are not mutually exclusive and many patients may have both of them. 

• Aqueous tear deficiency: It is characterized by inadequate tear production with predominant causes consisting of Sjogren Syndrome (primary or secondary), diseases of the lacrimal gland such as obstruction, or systemic drugs affecting tear production. Sjogren Syndrome is a chronic autoimmune disease that reduces the amount of moisture produced by the glands in the eyes and the mouth.
• Evaporative dry eye: It is characterized by increased tear film evaporation and is most frequently caused by meibomian gland dysfunction.  Meibomian glands line the eyelid margins and secrete oils that become the lipid layer of the tear film and reduce the evaporation of tears.  Meibomian gland dysfunction may be caused by inadequate secretion due to atrophy, drop out of the glands, or obstruction of the gland orifices.  Other major causes of increased tear evaporation include poor blinking (low rate, incomplete lid closure), disorders of the lid aperture, and environmental factors (low humidity, high airflow). 

2. Causes of dry eyes

Wondering what causes dry eyes? Dry itchy eyes are caused by a variety of reasons that disrupt the healthy tear film. Reasons for tear film dysfunction are many, including hormone changes, autoimmune disease, inflamed eyelid glands, or allergic eye disease. For some people, the cause of dry eyes is decreased tear production or increased tear evaporation. 

Decreased tear production

Dry eyes can occur when you're unable to produce enough water (aqueous fluid). The medical term for this condition is keratoconjunctivitis sicca.

Common causes of decreased tear production include:

• Aging
• Certain medical conditions including Sjogren's syndrome, allergic eye disease, rheumatoid arthritis, lupus, scleroderma, graft vs. host disease, sarcoidosis, thyroid disorders, or vitamin A deficiency
• Certain medications, including antihistamines, decongestants, hormone replacement therapy, antidepressants, and drugs for high blood pressure, acne, birth control, and Parkinson's disease
• Corneal nerve insensitivity is caused by contact lens use, nerve damage, or caused by laser eye surgery, though symptoms of dry eyes related to this procedure are usually temporary

Increased tear evaporation

The oil film produced by small glands on the edge of your eyelids (meibomian glands) might become clogged. Blocked meibomian glands are more common in people with rosacea or other skin disorders.

Common causes of increased tear evaporation include:

• Posterior blepharitis (meibomian gland dysfunction)
• Blinking less often, which tends to occur with certain conditions, such as Parkinson's disease; or when you're concentrating during certain activities, such as while reading, driving, or working at a computer
• Eyelid problems, such as the lids turning outward (ectropion) and the lids turning inward (entropion)
• Eye allergies
• Dry eyelids
• Preservatives in topical eyedrops
• Wind, smoke, or dry air
• Vitamin A deficiency

3. Symptoms of dry eyes

Dry eyes are usually accompanied by the following symptoms;

• Stinging, burning, or a feeling of pressure in the eyes. 
• A sandy, gritty, or foreign body sensation.
• Epiphora, or tearing. This is due to dryness, leading to pain or irritation that results in intermittent excess tearing.
• Pain is a broad term, and sharp and dull pain can be described, which may be localized to some part of the eye, behind the eye, or even around the orbit.
• Redness is a common complaint and is often made worse by the rebound effect of vasoconstrictors found in many over-the-counter eye drops designed to reduce redness. 
• Blurry vision, particularly intermittent blurry vision, is a common complaint and may also be described as glare or haloes around lights at night.
• A sensation of heavy eyelids or difficulty opening the eyes. 
• Dryness is a common problem for contact lens wearers, and irritation may make contact lenses uncomfortable or even impossible to wear.
• Tired eyes.  Closing the eyes may provide relief to some individuals with dry eyes.

4. Risk factors of dry eyes

Factors that make it more likely for you to experience dry eyes include:

• Being older than 50. Tear production tends to diminish as you get older. Dry eyes are more common in people over 50.
• Being a women A lack of tears is more common in women, especially if they experience hormonal changes due to pregnancy, using birth control pills, or menopause.
• Eating a diet that is low in vitamin A, which is found in liver, carrots, and broccoli, or low in omega-3 fatty acids, which are found in fish, walnuts, and vegetable oils.
• Wearing contact lenses or having a history of refractive surgery.

5. Complications of dry eyes

People with dry eyes may experience the following complications:

• Eye infections. Your tears protect the surface of your eyes from infection. Without adequate tears, you may have an increased risk of eye infection.
• Damage to the surface of your eyes. If left untreated, severe dry eyes may lead to eye inflammation, abrasion of the corneal surface, corneal ulcers, and vision loss.
• Decreased quality of life. Dry eyes can make it difficult to perform everyday activities, such as reading.

Treatment for dry eyes

Some of the most common dry eye treatments are as follows:

• Topical cyclosporine eye drops: These are given twice a day in each eye to treat the underlying inflammation in the tear glands so they produce more and better quality tears. It typically takes 1 to 4 months before the cyclosporine A drops reduce symptoms and signs of dry eye. These drops are safe although they may sting upon application.
• Lifitegrast: These drops are also done twice a day in each eye, to treat the underlying inflammation in the tear glands. 
• Artificial teardrops and ointments: The use of artificial teardrops is a palliative (soothing) treatment that helps symptoms for a few minutes but does not treat the underlying cause of dry eye disease. Artificial tears are available over the counter. No one drop works for everyone, so you might have to experiment to find the drop that works for you. If you have chronic dry eyes, it is important to use the drops even when your eyes feel fine, to keep them lubricated.
• Temporary punctal occlusion: Sometimes it is necessary to close the ducts that drain tears off the eye. This is done via a painless procedure where a plug is inserted into the tear drain of the lower eyelid. The plug will dissolve quickly. This is a temporary procedure.
• Permanent punctal occlusion: If temporary plugging of the tear drains works well or plugging is thought to be important for the health of the eye, then silicone plugs may be used. The permanent plugs will hold tears around the eyes as long as they are in place. They can be removed. Many patients find that the plugs improve comfort and reduce the need for artificial tears.
• Surgery: If needed, the ducts that drain tears into the nose can be permanently closed to allow more tears to remain around the eye. This is done with a local anesthetic on an outpatient basis. 
• Autologous serum drops: In severe cases of dry eye, artificial tears made from the patient's serum can be prepared and given 6 to 8 times a day in both eyes. This treatment, although often effective, is expensive.

Prevention of dry eyes

To prevent your eyes from running dry, you may take the following steps;

• Avoid air blowing in your eyes. Don't direct hair dryers, car heaters, air conditioners, or fans toward your eyes.
• Add moisture to the air. In winter, a humidifier can add moisture to dry indoor air.
• Consider wearing wraparound sunglasses or other protective eyewear. Safety shields can be added to the tops and sides of eyeglasses to block wind and dry air. Ask about shields where you buy your eyeglasses.
• Take eye breaks during long tasks. If you're reading or doing another task that requires visual concentration, take periodic eye breaks. Close your eyes for a few minutes. Or blink repeatedly for a few seconds to help spread your tears evenly over your eyes.
• Be aware of your environment. The air at high altitudes, in desert areas, and on airplanes can be extremely dry. When spending time in such an environment, it may be helpful to frequently close your eyes for a few minutes at a time to minimize the evaporation of your tears.
• Position your computer screen below eye level. If your computer screen is above eye level, you'll open your eyes wider to view the screen. Position your computer screen below eye level so that you won't open your eyes as wide. This may help slow the evaporation of the tears between the time in which your eye blinks.
• Stop smoking and avoid smoke. If you smoke, ask your doctor to help devise a quit-smoking strategy that's most likely to work for you. If you don't smoke, stay away from people who do. Smoke can worsen dry eye symptoms.
• Use artificial tears regularly. If you have chronic dry eyes, use eye drops even when your eyes feel fine to keep them well lubricated.

Conclusion

Our eyes convey various emotions through tears. Tears not only speak our minds but also help us see clearly and wash away dirt from our eyes. Dry eyes are a common eye disorder affecting many people. In this condition, tears are not able to adequately lubricate our eyes, resulting in numerous uncomfortable symptoms like stinging and burning of the eyes. This condition may also bring along certain complications such as eye infections, damage to the eye's surface, and a lowered quality of life.

Dry eyes may be painful but you can take care of them. Various medicines like topical eye drops are available to treat dry eyes. Artificial tears can also be used. In addition to this, surgical options and autologous serum drops are also available to cure dry eyes. 

It is always better to take steps to prevent eye damage like avoiding air being blown in your eyes, adding moisture to the air, using eye shields, avoiding smoking, etc.

Don't forget to see a doctor if the dry eyes are persistent and Take care of your eyes.