What causes dry eyes

Our eyes need tears to stay healthy and comfortable. If your eyes do not produce enough tears, it is called dry eye. Dry eye is also when your eyes do not make the right type of tears or tear film. In severe cases, the clear covering on the eye (cornea) may become damaged or infected.

Experts estimate that dry eye affects millions of adults in the United States. The risk of developing dry eye increases with advancing age. Women have a higher prevalence of dry eye compared with men.

How do tears work ?

When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision.

The tear film is made of three layers:

• An oily layer
• A watery layer
• A mucus layer

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 (also called tarsal glands). Inflammation of the oil glands along the edge of the eyelid, common in patients with roseacea, causes early breakdown and evaporation of the tear film.

The watery layer is the middle of the tear film. It makes up most of what you 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. Unfortunately, inflammatory conditions like rheumatoid arthritis, Sjogrens disease as well as aging and menopause lead to decreased tear production. As tear production diminishes, the surface of the eye starts to dry out.

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.

Normally, your eyes constantly make tears to 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, you end up with dry eyes.

The brain sensing the eye is both dry and irritated and in turn signals the main tear glands to flush the eye. As a result, the dry eye paradoxically tears and becomes watery. People with dry eyes note intermittent tearing of the eyes during activities like reading, driving, watching TV, using a computer or going outside on a windy day. These all cause the eye to dry out because the eye blinks less during these activities.

The lacrimal (tear) apparatus

The lacrimal (tear) apparatus (Figure 1) is a group of structures that produces and drains lacrimal fluid (tears) in a process called lacrimation. The lacrimal apparatus consists of the lacrimal (tear) gland and a series of ducts that drain the tears into the nasal cavity. The lacrimal gland, about the size and shape of an almond, is nestled in a shallow fossa of the frontal bone in the superolateral corner of the orbit. About 6-12 short ducts lead from the gland to the surface of the conjunctiva.

The lacrimal (tear) glands are supplied by parasympathetic fibers of the facial (VII) nerves. The lacrimal fluid produced by these glands is a watery solution containing salts, some mucus, and lysozyme, a protective bactericidal enzyme to prevent infection. Tear fluid protects, cleans, lubricates, moistens the eyeball and delivers oxygen and nutrients to the conjunctiva. After being secreted from the lacrimal gland, tear fluid is spread medially over the surface of the eyeball by the blinking of the eyelids. Each lacrimal gland produces about 1 mL of lacrimal fluid per day

After washing across the eye, tears collect near the medial commissure and flow into a tiny pore, the lacrimal punctum, on the margin of each eyelid. The punctum opens into a short lacrimal canaliculus, which leads to the lacrimal sac in the medial wall of the orbit. From this sac, a nasolacrimal duct carries the tears to the inferior meatus of the nasal cavity; thus an abundance of tears from crying or watery eyes can result in a runny nose. Once the tears enter the nasal cavity, they normally flow back to the throat and are swallowed.

An obstruction of the tear ducts may occur due to numerous reasons (aging, trauma, inflammatory conditions, medications and tumors) and cause numerous signs and symptoms ranging from wateriness or tearing to discharge, swelling, pain and infection. These signs and symptoms may result from the tear drainage system becoming obstructed at any point from the puncta to the nasal cavity.

What Are the Symptoms of Obstructed Tear Ducts ?

If the tear passageways become blocked, tears cannot drain properly and may overflow from the eyelids onto the face as if you were crying. In addition to excessive tearing you may also experience blurred vision, mucous discharge, eye irritation, and painful swelling in the inner corner of the eyelids. A thorough examination by an ophthalmic plastic surgeon can determine the cause of tearing and recommended treatment.

How is an Obstructed Tear Duct Treated or Repaired ?

Depending on your symptoms and their severity, your specialist will suggest an appropriate course. In mild cases, a treatment of warm compresses and antibiotics may be recommended. In more severe cases, surgical intervention to bypass the tear duct obstruction (dacryocystorhinostomy surgery) may be recommended. A dacryocystorhinostomy is performed by creating a new tear passageway from the lacrimal sac to the nose, bypassing the obstruction. A small silicone tube called a stent may temporarily be placed in the new passageway to keep it open during the healing process. In a small percentage of cases, the obstruction is between the puncta and the lacrimal sac. In these cases, in addition to the dacryocystorhinostomy procedure, the surgeon will insert a tiny artificial tear drain called a Jones Tube. A Jones Tube is made of Pyrex glass and allows tears to drain directly from the eye to the lacrimal sac.

Dacryocystorhinostomy surgery is usually performed as an outpatient procedure. Patients usually have some bruising and swelling on the side of the nose that subsides in one to two weeks. In general, surgery has a greater than 90% success rate and most patients experience a resolution of their tearing and discharge problems once surgery and recovery are completed.

Figure 1. Eyes tear glands and anatomy

Dry eye symptoms

Here are some of the symptoms of dry eye.

• You feel like your eyes are stinging and burning
• There is a scratchy or gritty feeling like something is in your eye
• There are strings of mucus in or around your eyes
• Your eyes are red or irritated. This is especially true when you are in the wind or near cigarette smoke
• It is painful to wear contact lenses
• You have lots of tears in your eyes

Having a lot of tears in your eyes with “dry eye” might sound odd. But your eyes make more tears when they are irritated by dry eye.

When to Contact a Medical Professional

See your doctor right away if:

• You have red or painful eyes.
• You have flaking, discharge, or a sore on your eye or eyelid.
• You have had an injury to your eye, or if you have a bulging eye or a drooping eyelid.
• You have joint pain, swelling, or stiffness and a dry mouth along with dry eye symptoms.
• Your eyes do not get better with self-care within a few days.

Dry eyes causes

People tend to make fewer tears as they get older due to hormonal changes. Both men and women can get dry eye. However, women are more likely to develop dry eye. Hormonal changes during pregnancy and after menopause have been linked with dry eye. Women also have an increased risk for autoimmune disorders.

Here are some other causes of dry eye.

• Certain diseases, such as rheumatoid arthritis, Sjögren’s syndrome, thyroid disease, scleroderma and lupus
• Diabetes, thyroid disorders and Vitamin A deficiency are associated with dry eye.
• Blepharitis (an inflammatory eyelid disease – when eyelids are swollen or red)
• Rosacea (an inflammatory skin disease)
• Entropion (when eyelids turn in); ectropion (eyelids turn outward)
• Smoking or second-hand smoke exposure
• Wind or a very dry climate or environment (wind, air conditioning)
• Looking at a computer for a long time (reduced blinking)
• Using contact lenses for a long time
• Having refractive eye surgery, such as LASIK
• Sun exposure
• Heat or chemical burns
• Previous eye surgery
• Prolonged periods of screen time encourage insufficient blinking.

Taking certain medicines, such as:

• Diuretics (water pills) for high blood pressure
• Beta-blockers, for heart problems or high blood pressure
• Allergy (antihistamines)
• Sleeping pills
• Anxiety medicines
• Cold medicines decongestants,
• Antidepressants,
• Birth control pills,
• Hormone replacement therapy to relieve symptoms of menopause
• Medications for Parkinson’s disease.

Tell your eye doctor about all the prescription and non-prescription medicines you take.

Dry eye prevention

• Try not to use a hair dryer, if possible.
• Stay away from very warm rooms. In the winter, add moisture to the air with a humidifier. Or put a pan of water near your heater or radiator.
• Protect your eyes from drying wind by wearing wrap-around glasses outside.
• Talk to your eye doctor about adding omega-3 fatty acids to your diet for dry eye relief. They are found naturally in oily fish (such as salmon, sardines, tuna, trout, and anchovies), and in flaxseeds. Omega-3 fatty acids can be added as a dietary supplement (pill or tablet).
• Do you wake up with dry and scratchy eyes? Use artificial tear ointment or thick eye drops just before you go to bed.

What are the symptoms of dry eye ?

Dry eye causes a scratchy sensation or the feeling that something is in the eye. Other symptoms include stinging or burning, episodes of excess tearing that follow periods of dryness, discharge, pain, and redness in the eye. People with dry eye may also feel as if their eyelids are heavy and may experience blurred vision.

Dry eyes remedy

Artificial tears

Your eye doctor might tell you to use artificial tears. These are eye drops that are like your own tears. You can use artificial tears as often as you need to. You can buy artificial tears without a prescription. There are many brands. Try a few until you find a brand that works best for you.

If you use artificial tears more than six times a day or are allergic to preservatives, you should use preservative-free tears. This is because if the tears with preservatives are used a lot, these chemicals may start to irritate your eyes.

Conserving tears

Your eye doctor may suggest blocking your tear ducts. This makes your natural tears stay in your eyes longer. Punctal plugs made of silicone or collagen may be inserted by an eye care professional to partially or completely plug the tear ducts at the inner corners of the eye to keep tears from draining from the eye. These plugs can be removed later as needed. In severe cases, surgical closure of the drainage ducts by thermal punctal cautery may be recommended to close the tear ducts permanently.

Increasing your tears

Your ophthalmologist might have you use a special eyedrop medication. This helps your eyes make more of their own tears.

Treating dry eye culprits

If your eyes are irritated, your ophthalmologist can treat those problems. They may recommend:

• Prescription eye drops or ointments. Cyclosporine and lifitegrast are the only prescription medications approved by the U.S. Food and Drug Administration for treating dry eye. Corticosteroid eye drops also may be prescribed short-term to reduce eye inflammation.
• Warm compresses on the eyes
• Massaging your eyelids
• Certain eyelid cleaners.

Natural remedies for dry eyes

• Fish oil 2 to 3 times per day
• Glasses, goggles or contact lenses that keep moisture in the eyes

Other helpful steps include:

• DO NOT smoke and avoid second-hand smoke, direct wind, and air conditioning.
• Use a humidifier, particularly in the winter.
• Limit allergy and cold medicines that may dry you out and worsen your symptoms.
• Purposefully blink more often. Rest your eyes once in a while.
• In cases of Meibomian gland dysfunction, warm lid compresses and clean eyelashes regularly.

Some dry eye symptoms are due to sleeping with the eyes slightly open. Lubricating ointments work best for this problem. You should use them only in small amounts since they can blur your vision. It is best to use them before sleep.

Surgery may be helpful if symptoms are because the eyelids are in an abnormal position.

Contacts for dry eyes

Soft contact lenses may be necessary in the dry eye to provide an optical surface to the cornea when it is the site of destructive changes. In the case of the severely dry eye it may be necessary to use a silicone soft lens with no water content in order to obviate the problems of dehydration.

• There are considerable dangers in such eyes with and without conjunctival and corneal destructive changes and a decision to fit a lens should not be taken lightly and without adequate supervision and close follow up with an eye specialist.