Key findings:

The abstract highlights dry eye syndrome as a prevalent condition globally, affecting 5 to 50 percent of various populations. It emphasizes the chronic lack of sufficient lubrication and moisture on the eye's surface as the primary cause, leading to a range of symptoms from mild irritation to significant inflammation, often managed with artificial tears and behavioral adjustments.

What is known and what is new?

The abstract outlines the well-established understanding of dry eye syndrome as a prevalent condition characterized by insufficient lubrication and moisture on the eye's surface, leading to various symptoms. However, it also highlights the importance of routine use of artificial tears and behavioral modifications in managing symptoms and improving patient comfort, underscoring the significance of these approaches in clinical practice.

What is the implication, and what should change now?

The prevalence of dry eye syndrome underscores the need for increased awareness among both patients and healthcare providers regarding its causes, symptoms, and management strategies. Clinicians should prioritize educating patients about preventive measures and treatment options, emphasizing the importance of regular eye care and adherence to prescribed therapies for better symptom control and quality of life.

Tears are necessary for maintaining the health of the front surface of the eye and for providing clear vision. Dry eye is a condition in which a person doesn't have enough quality tears to lubricate and nourish the eye. [1,2]

Dry eye disease (DED), also known as dry eye syndrome (DES), keratoconjunctivitis sicca (KCS), and keratitis sicca, is a multi-factorial disease of the tears and the ocular surface that results in discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. [3,4]

Dry eye is a common and often chronic problem, particularly in older adults. With each blink of the eyelids, tears spread across the front surface of the eye, known as the cornea. Tears provide lubrication, reduce the risk of eye infection, wash away foreign matter in the eye and keep the surface of the eyes smooth and clear. Excess tears in the eyes flow into small drainage ducts in the inner corners of the eyelids, which drain into the back of the nose. Dry eyes can occur when tear production and drainage is not in balance. [2,5]

Symptoms [6,7]

Signs and symptoms, which usually affect both eyes, may include:

• A stinging, burning or scratchy sensation in your eyes
• Stringy mucus in or around your eyes
• Sensitivity to light
• Eye redness
• A gritty feeling or sensation of having something in your eyes or feeling of having sand in your eyes.
• Eyes get tired faster than they used to
• Difficulty reading or sitting at the computer for long periods
• Difficulty wearing contact lenses
• Difficulty with nighttime driving
• Watery eyes or too many tears .This confusing condition is called reflex tearing. It happens because the lack of moisture irritates the eyes. It sends a distress signal through the nervous system for more lubrication. The body sends a flood of tears to try to make up for the dryness.
• Blurred vision or eye fatigue
   

Causes [6-9]

Dry eyes are caused by a variety of reasons that disrupt the healthy tear film. Tear film has 3 layers: the oily outer layer, the watery middle layer, and the inner mucus layer. This combination normally keeps the surface of the eyes lubricated, smooth & clear. 

Each layer of the tear film serves a purpose.

• The oily layer is the outside of the tear film. It makes the tear surface smooth and keeps tears from drying up too quickly. This layer is made in the eye’s meibomian glands.
• The watery layer is the middle of the tear film. 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.
• The mucus layer is the inner layer of the tear film. 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

The cause of dry eyes is either decreased tear production or increased tear evaporation. If the glands that produce the various elements of the tear film are inflamed or don’t produce enough water, oil, or mucus, it can lead to dry eye .When oil is missing from the tear film, they quickly evaporate and the eyes can’t maintain a steady supply of moisture. Reasons for tear film dysfunction are many, including hormone changes, autoimmune disease, inflamed eyelid glands or allergic eye disease.

Decreased Tear Production

Dry eyes can occur when a person is unable to produce enough water (aqueous fluid). The medical term for this condition is kerato-conjunctivitis 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
• Some  medications, including antihistamines, nasal decongestants, hormone replacement therapy, antidepressants, and drugs for high blood pressure, acne, birth control  pills and Parkinson's disease 
• Corneal nerve de-sensitivity caused by contact lens use, nerve damage or that 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 the 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 screen for long periods of time, can also contribute to drying of the eyes.
• Eyelid problems, such as the lids turning outward (ectropion) and the lids turning inward (entropion)
• Long-term contact lens wear
• Eye allergies
• Preservatives in topical eye drops
• Exposure to smoke, wind, dry climates and constant exposure to heaters in winters can increase tear evaporation resulting in dry eye symptoms.  
• Vitamin A deficiency
• Refractive eye surgeries, such as LASIK, can decrease tear production and contribute to dry eyes.

Risk Factors [6-11]

Factors that make it more likely that you'll experience dry eyes include:

• Being older than 50. Tear production tends to diminish as a person gets older. Dry eyes are more common in people over 50.
• Being a woman. A lack of tears is more common in women, especially if they experience hormonal changes due to pregnancy, using birth control pills or menopause.
• If a person has chronic allergies
• In thyroid disease or other conditions that push the eyes forward
• In autoimmune disease like lupus, rheumatoid arthritis, and other immune system disorders
• In exposure keratitis, which occurs from sleeping with eyes partially open
• 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.

Complications [6-13]

People who have dry eyes may experience these 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.

Prevention [6-16]

• 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: Wear sunglasses outdoors, particularly those with wraparound frames, to reduce exposure to drying winds and the sun.
• Safety shields can be added to the tops and sides of eyeglasses to block wind and dry air. 
• Take eye breaks during long tasks. If you're reading or doing another task that requires visual concentration, take periodic eye breaks. When reading or staring at a computer screen for long periods of time, 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 in 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 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 your tears between eye blinks.
• Stop smoking and avoid smoke. If you smoke, ask your doctor for help devising 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.
• Nutritional supplements containing essential fatty acids may help decrease dry eye symptoms in some people. Ask your doctor if taking dietary supplements could help your dry eye problems.
• Avoiding becoming dehydrated by drinking plenty of water (8 to 10 glasses) each day.
• Get enough sleep -about 7 to 8 hours a night.

Diagnosis [6-18]

Dry eyes can be diagnosed through a comprehensive eye examination. Testing with emphasis on the evaluation of the quantity and quality of tears produced by the eyes may include:

• Patient history to determine the patient's symptoms and to note any general health problems, medications or environmental factors that may be contributing to the dry eye problem.
• External examination of the eye, including lid structure and blink dynamics.
• Evaluation of the eyelids and cornea using bright light and magnification.
• Measurement of the quantity and quality of tears for any abnormalities. Special dyes may be put in the eyes to better observe tear flow and to highlight any changes to the outer surface of the eye caused by insufficient tears.

• Some tests could be done like

   

1. Slit lamp test: The doctor will use a microscope to see if the eyes are producing enough tears.
2. Schirmer’s test: The doctor will use a small piece of paper to measure how moist the eyes are.
3. Tear breakup time: The doctor will use this test to check how long the tear film remains after a person blinks

Treatment [6-20]

• Use artificial tears drops or ointments regularly. Artificial tears drops increase the moisture of the eyes. If anyone has chronic dry eyes, use eye drops even when the eyes feel fine to keep them well lubricated.. If the eyes dry out during sleep, a person can use a thick product, like an ointment, at night.
• Temporary punctal occlusion or Lacrimal plugs .Doctor might opt to close the punctum, or duct that drains tears from the eye. They might start with a temporary plug designed to dissolve over time.. This is a relatively painless, reversible procedure that slows tear loss. If  condition is severe, the plugs may be recommended as a permanent solution
• Non dissolving punctal plugs and punctal occlusion by cautery (application of heat to tear exit duct). If temporary plugs work well, doctors may move to longer-lasting ones or may go right to a long-lasting plug. Or they could choose a procedure called cautery. A person might get a drug that relaxes, and then use a special tool to burn the opening shut. The scar that forms makes a permanent plug. These measures increase the tear level by blocking the “drainpipe” through which tears usually go from your eye to the nose. Tear plugs are easy to remove, but sometimes they come out on their own or fall down the tear drain. They can make the eyes feel better and lower the need for artificial tears.
• Lipiflow. This medical device uses heat and pressure to unclog blocked glands on the eyelids. These glands produce the oil in your tears. It keeps the eye moist and prevents the tears from evaporating.
• Medications: The most commonly prescribed medication for dry eye syndrome is an anti-inflammatory called cyclosporine (Restasis). The drug increases the amount of tears in the eyes and lowers the risk of damage to cornea. If dry eye is severe, a person may need to use corticosteroid eye drops for a short time while the medication takes effect. Alternative medications include cholinergics, such as pilocarpine. Lifitegrast drops are taken twice daily to kick-start tear production. These all medications help stimulate tear production. If another medication is causing the eyes to become dry, the doctor may switch the prescription to try to find one that doesn’t dry out the eyes.
• Testosterone cream. Dry eyes can be related to a lack of testosterone in the oil glands on the eyelids. The doctor might give a testosterone cream that can be applied to the eyelids. It can help the oil glands work better.

• Nutrition: Adding fish oil or omega-3 to the diet or can also help.

   

Funding: No funding sources.

Conflict of interest: None declared.

Ethical approval: The study was approved by the Institutional Ethics Committee of Indira Gandhi Medical College.

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