Dry eye – Dry eye syndrome

Is your eye chronically dry, itchy, and stinging? Are you finding it harder to wear contact lenses? Do you sometimes experience significant tearing when exposed to cold or wind, for reasons you can't explain? You may be suffering from dry eye, also known as dry eye syndrome. This is a common problem, rarely serious, but debilitating. Dry eye is one of the most frequent reasons for consulting an ophthalmologist and is perceived by patients as a major source of discomfort.

How do tears work?

When you blink, a film of tears spreads across the eye. This keeps the surface of the eye smooth, even, and clear. The tear film is essential for good vision.

The tear film is composed of three layers:

A lipid layer – Composed of fats
An aqueous layer – Water
A layer of mucus – An assembly of proteins

Each layer of the tear film has a role to play.

The lipid layer is the outermost layer of the tear film. It makes the surface of the tears smooth and prevents them from evaporating too quickly. This layer is produced by the meibomian glands on the edge of the eyelids.
The aqueous layer is the middle layer of the tear film. It makes up the majority of what we see as tears. This layer cleans the eye, removing particles that don't belong there. This layer originates from the main and minor lacrimal glands located in the eyelids.
The mucin layer is the innermost layer of the tear film. It distributes the aqueous layer across the surface of the eye, keeping it moist. Without mucus, tears would not adhere to the eye. Mucus is produced in the conjunctiva, the transparent tissue that covers the white of the eye and the inside of the eyelids.

The symptoms

Here are the main symptoms that should make you suspect a drought:

You feel like your eyes are stinging and burning.
Your vision is blurry, especially when reading.
You have a foreign body sensation – The feeling that something is in your eye.
You have mucus filaments 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.
Wearing contact lenses is painful or uncomfortable. You cannot wear your lenses for too long.
Your eyes water when you are irritated, but this does not relieve the pain.

Paradoxical tearing:

Many patients also describe debilitating paradoxical tearing, particularly when exposed to cold air or wind. This is linked to a qualitative tear deficiency. The eye reacts by secreting a large amount of tear film.

Causes and risk factors

Dry eye is usually caused by poor tear quality (qualitative deficiency), or sometimes simply by a decrease in tear production (quantitative deficiency). Paradoxically, one can also have dry eyes and experience excessive tearing.

Due to hormonal changes, your eyes tend to produce fewer tears as you age. Both men and women can experience dry eye. However, it is more common in women, especially those who are menopausal.

But there are other contributing risk factors:

Certain diseases, such as rheumatoid arthritis, Sjögren's syndrome, thyroid diseases and lupus.
Blepharitis – When the eyelids are swollen, inflamed or red.
Entropion – Malposition of the eyelid turned inwards.
Ectropion – Malposition of the eyelid turned outwards.
Conjunctivochalasis – Horizontal folds of conjunctiva along the edge of the lower eyelid.
The environment – Being in smoke, wind or a very dry climate.
Working and looking at a computer screen for long periods, reading, and engaging in other activities that reduce blinking.
Wearing contact lenses for extended periods.
To undergo refractive eye surgery, such as LASIK.

Taking certain medications , such as:

Diuretics for high blood pressure.
Beta-blockers for heart problems or high blood pressure.
Antihistamines – Medications for allergies and colds.
Sleeping pills.
Anti-anxiety medications and antidepressants.
Medications for heartburn.

Inform your ophthalmologist about all prescription and over-the-counter medications you are taking.

Diagnosis of dry eye

Your ophthalmologist will begin with an eye examination. They will examine your eyelids and the surface of your eye. They will also check how you blink.

Your ophthalmologist will look for:

Chronic inflammation of the eyelids: blepharitis or rosacea.
An eye allergy.
A defect in optical correction.
Signs in favor of a general disease such as Gougerot-Sjogren syndrome – an autoimmune disease inducing a true dry syndrome of all mucous membranes.

There are many different tests that can diagnose dry eye. Most often, the ophthalmologist will use a drop of a dye called Fluorescein®. This dye colors the tears and allows their behavior to be analyzed.

Homogeneity of the tear film.
Distribution across the eye.
Stability and breakup time of the tear film: break up time.

In cases of severe dryness due to underproduction, a quantitative analysis using strips placed on the edge of the eyes can determine the amount of tears produced. This is the Schirmer test, which measures tear production in millimeters over 3 or 5 minutes.

Treatment for dry eye

It is recommended to consult your ophthalmologist, at least once, to confirm the diagnosis and ensure the absence of associated pathologies.
The treatments put in place then aim to replace the lack of tears, improve their quality and sometimes decrease their drainage through the lacrimal pathways in order to reduce the need for eye drops.
Treat dry eyes by adding tears
Your ophthalmologist may advise you to use artificial tears. These are thick eye drops that resemble your own tears. You can use artificial tears as often as needed.
You can buy artificial tears without a prescription. There are many brands available. There's no such thing as the perfect artificial tear! Try a few until you find the brand that works best for you.
If you use artificial tears regularly or are allergic to preservatives, you should use preservative-free tears. Tears containing preservatives can irritate your eyes.
Artificial tears are perfectly compatible with contact lenses. Feel free to instill a drop before inserting them, then during the day, and again when removing them to improve your symptoms.

Treating dry eye by conserving tears

Your ophthalmologist may suggest blocking your tear ducts. This allows natural tears and eye drop substitutes to stay in your eyes longer.
Tiny silicone plugs called punctal plugs are inserted at the entrance of your tear ducts. These plugs remain in the inner corner of your eyelid; they are completely painless and invisible. They can be removed later if necessary.
If plugging provides relief, but they do not last long, your ophthalmologist may also recommend surgery that permanently closes your tear ducts.

Control the environment and external aggressions

The following avoidance measures are also recommended, as all these factors contribute to a greater or lesser extent to increased dryness of the eyes:

Avoid polluted environments.
Limit exposure to irritants such as makeup and cigarette smoke.
Take breaks when working on a screen, force yourself to blink.
Reduce the use of air conditioning and heating.
Soothe the inflammation of your eyelids by applying warm compresses morning and evening, then gently massaging.

Treatments for severe drought

In cases where the condition is refractory to eye drops and tear plugs, the following treatments can be used:

Cyclosporine – This is a treatment that modulates the immune response on the surface of the eye to reduce inflammation and improve tear quality. The eye drops are dispensed at a hospital pharmacy.
Autologous serum – This is your own serum, drawn from your veins regularly and then stored in a vial. Autologous serum provides numerous nutrients and anti-inflammatory factors. The treatment is extremely demanding, but very effective in treating Sjögren's syndrome.
Scleral lenses – Rigid lenses with a wide base that sit on the eye and are filled with saline solution. They allow the cornea to be constantly bathed in a hydrating solution.
Humid chamber goggles – Another option, these goggles allow the surface of the eye to be constantly moistened.

Complications

Dry eye, in addition to causing discomfort and poor vision, can damage the cornea. In order of progression and severity, dry eye will lead to:

Keratitis – The cornea becomes irregular, lumpy, due to alteration of its outer layer.
An ulcer – The cornea becomes hollow due to external aggressions.
An abscess – The ulcer becomes infected due to a lack of washing effect from the aqueous phase of tears.
A scar – The ulcer heals haphazardly and leaves a scar-like appearance.
A perforation – The ulcer burrows and perforates the cornea, allowing the contents of the eye to drain out.

What precautions can be taken to prevent dry eyes?

There are a few things you can do to combat dry eyes:

For every hour spent reading or watching television, take a break and look away from the screen for at least 20 seconds.
Blink rapidly and use preservative-free lubricating eye drops such as Vismed®, Thealose®, or Artelac®. Avoid eye drops containing antiseptics or antihistamines.
At bedtime, instill a drop of eye gel or ointment. These treatments will help keep your eyes moist overnight.
Adopt a balanced and varied diet. Add fish like salmon and oilseeds (walnuts, almonds, etc.) to your diet; they are rich in fatty acids and omega-3s, which enrich the aqueous layer. The richer the layer, the better it covers the tears, thus preventing evaporation. If you are allergic to nuts or don't like fish, try a dietary supplement instead.
If symptoms persist, do not hesitate to consult an ophthalmologist specializing in dry eye.

Sources:
https://eyewiki.org/Category:Articles
https://www.cahiers-ophtalmologie.fr/
https://snof.org/
https://couf.fr/