Dry Eye Disease

How dry eye disease develops

The tear film has three layers: an inner mucus layer that helps tears stick to the eye, a middle watery layer made by the lacrimal glands, and an outer oil layer from the meibomian glands in the eyelid margins that slows evaporation.

When any layer fails, the tears become too salty (hyperosmolar). This irritates the eye surface, triggers inflammation, and damages the cells and glands that make tears, which makes the tears worse still. This "vicious circle" is why dry eye is a chronic disease rather than a passing irritation. For the everyday symptom and quick relief, see dry eyes.

Types of dry eye

Many people have both types at once.

Symptoms

• Gritty, sandy or foreign-body feeling
• Burning, stinging or itching
• Red eyes
• Blurred vision that clears with blinking
• Light sensitivity
• Tired eyes, worse with reading or screens
• Stringy mucus
• Watery eyes: a reflex flood of watery tears in response to irritation, which surprises many people
• Discomfort with contact lenses

Symptoms and test results often do not match: some people with severe surface damage feel little, while others with mild signs have intense pain.

Causes and risk factors

• Age over 50, and female sex, especially after menopause
• Long screen use: blinking falls by up to half when concentrating
• Contact lens wear
• LASIK and other eye surgery, which cut corneal nerves
• Medicines: antihistamines, decongestants, antidepressants, isotretinoin, diuretics, beta-blockers, hormone therapy and some glaucoma drops with preservatives
• Autoimmune disease: Sjögren's syndrome, rheumatoid arthritis, lupus
• Thyroid eye disease and incomplete lid closure (lagophthalmos)
• Rosacea, diabetes, vitamin A deficiency
• Dry, windy or air-conditioned environments and cigarette smoke

How it is diagnosed

An eye doctor will ask about symptoms (often with a questionnaire such as OSDI), medicines, general health and screen time, then examine the eye with a slit lamp:

1. Tear break-up time: a fluorescein dye shows how many seconds the tear film stays intact. Under 10 seconds is abnormal.
2. Surface staining: dyes highlight damaged cells on the cornea and conjunctiva.
3. Schirmer test: a strip of paper in the lower lid measures tear production over 5 minutes.
4. Meibomian gland exam: pressing the lid to check oil quality, and sometimes imaging the glands.
5. Tear osmolarity and MMP-9 tests in some clinics, which measure saltiness and inflammation.

Blood tests for Sjögren's antibodies are done if aqueous deficiency, dry mouth or joint symptoms are present.

Treatment

Treatment follows a stepped approach from the American Academy of Ophthalmology and the TFOS DEWS II report:

Step 1: everyday measures

• Artificial tears: use preservative-free versions if you need them more than 4 times a day. Gels and ointments at night.
• Warm compresses and lid hygiene: 5 to 10 minutes of heat to melt thickened oil, then gentle lid cleaning.
• Screen habits: the 20-20-20 rule (every 20 minutes, look 20 feet away for 20 seconds) and deliberate full blinks.
• Humidifier, avoiding fans and car vents blowing on the face.
• Review medicines that dry the eyes.
• Omega-3 supplements have mixed evidence. A large US trial found no benefit over placebo.

Step 2: prescription and office treatments

• Anti-inflammatory drops: cyclosporine, lifitegrast, or short courses of mild steroid drops.
• Perfluorohexyloctane drops, which reduce evaporation, and varenicline nasal spray, which stimulates natural tear production.
• Punctal plugs: tiny plugs in the tear drainage ducts to keep tears on the eye.
• Meibomian gland treatments: thermal pulsation devices, intense pulsed light, and oral doxycycline or azithromycin for their anti-inflammatory effect.

Step 3: severe disease

• Autologous serum eye drops made from your own blood
• Scleral contact lenses that hold a fluid reservoir over the cornea
• Amniotic membrane, or surgery to partly close the eyelids

Complications

Untreated, severe dry eye can lead to eye infections, corneal abrasions and ulcers, scarring and reduced vision. It also makes contact lens wear difficult and can affect the accuracy of measurements before cataract surgery.

Frequently asked questions

Is dry eye disease permanent?

It is usually chronic, meaning it needs ongoing management, but symptoms can be well controlled. Dry eye caused by a medicine, contact lenses, a dry environment or recent eye surgery can improve a lot once the cause is addressed.

What is the difference between dry eyes and dry eye disease?

Dry eyes can be a short-lived symptom from wind, screens or tiredness. Dry eye disease is a chronic condition with an unstable tear film, inflammation and damage to the eye surface that an eye doctor can see on examination. It usually needs a longer-term treatment plan.

Why do my eyes water if I have dry eye?

Irritation from a dry eye surface triggers reflex tearing: the lacrimal gland floods the eye with watery tears. These tears lack enough oil and mucus to stay on the eye, so they spill over without fixing the dryness.

What is the best eye drop for chronic dry eye?

Preservative-free artificial tears are the first choice. If they are not enough, an eye doctor may prescribe anti-inflammatory drops such as cyclosporine or lifitegrast, or perfluorohexyloctane for evaporative dry eye. Avoid long-term use of redness-relief drops, which worsen dryness.

Can dry eye cause blurry vision?

Yes. An uneven tear film scatters light, causing blurred or fluctuating vision that often clears briefly after blinking. Blur that does not improve with blinking, or comes with pain, needs an eye exam to rule out other problems.