What Causes Dry Eyes? A Complete Guide

Dry eye disease affects millions of Canadians, but the causes are not always obvious. Understanding what is behind your symptoms is the first step to getting the right treatment — because dry eye is not a one-size-fits-all condition.

In this guide, we break down the most common causes of dry eyes, explain how each one leads to symptoms, and point you toward the next step. If you already know you have dry eye and want to explore treatment, visit our Dry Eye Treatment page.

Meibomian Gland Dysfunction (MGD)

This is the number one cause of dry eye, responsible for roughly 85% of cases. The meibomian glands in your eyelids produce the oily layer of your tear film. When these glands become blocked or stop functioning properly, tears evaporate too quickly — a condition called evaporative dry eye.

MGD is often caused by chronic eyelid inflammation (blepharitis), Demodex mites, or long-term contact lens wear. It tends to worsen gradually and often goes undiagnosed until symptoms become significant.

Treatment: In-office IPL therapy and radiofrequency are the most effective ways to restore meibomian gland function. Learn about IPL therapy.

Aging

Tear production naturally decreases with age, especially after 50. The meibomian glands also deteriorate over time, contributing to evaporative dry eye. Women are disproportionately affected due to hormonal changes during menopause.

Treatment: Age-related dry eye typically responds well to a combination of artificial tears, prescription drops, and lifestyle adjustments. In-office treatments can help if MGD is a contributing factor.

Screen Time and Digital Eye Strain

When you focus on a screen, your blink rate drops by up to 60%. Each blink spreads a fresh layer of tears across the eye surface — fewer blinks means faster tear evaporation and increased dryness. This is especially problematic for people who work on computers for 6+ hours a day.

What you can do: Follow the 20-20-20 rule (every 20 minutes, look at something 20 feet away for 20 seconds), consciously blink during screen work, and position your monitor slightly below eye level so your eyes are not wide open.

Contact Lens Wear

Contact lenses sit on the tear film and can disrupt its stability, accelerate evaporation, and reduce oxygen flow to the cornea. Long-term lens wear can also contribute to MGD. Dry eye is the leading reason people stop wearing contacts.

What you can do: Switch to daily disposable silicone hydrogel lenses, use rewetting drops, and give your eyes regular breaks from contacts. If symptoms persist, talk to your optometrist about whether contacts are still right for you.

Environmental Factors

Dry air, wind, smoke, and air conditioning all accelerate tear evaporation. In Squamish, indoor heating during cold winters is a major contributor — heated air has very low humidity, and spending long hours indoors compounds the effect.

What you can do: Use a humidifier at home (especially in the bedroom), wear wraparound sunglasses in wind, and avoid sitting directly in front of heating vents or fans.

Medications

Many common medications have dry eye as a side effect. The most frequent culprits include:

• Antihistamines (allergy medications like Benadryl, Claritin)
• Decongestants
• Antidepressants and anti-anxiety medications
• Blood pressure medications (beta-blockers, diuretics)
• Hormone replacement therapy
• Isotretinoin (Accutane)

What you can do: Do not stop medications without consulting your prescribing doctor, but mention your dry eye symptoms to them. Sometimes a dosage adjustment or alternative medication can help. In the meantime, preservative-free artificial tears can manage symptoms.

Hormonal Changes

Estrogen and androgen hormones affect tear production and meibomian gland function. Women are significantly more likely to develop dry eye, especially during pregnancy, perimenopause, and menopause. Hormone replacement therapy and oral contraceptives can also contribute.

Treatment: Hormonal dry eye often requires a combination approach — prescription anti-inflammatory drops alongside artificial tears and in-office treatments if MGD is also present.

Blepharitis

Blepharitis is chronic inflammation of the eyelids, usually along the lash line. It frequently co-occurs with dry eye disease — the inflammation disrupts the meibomian glands and destabilizes the tear film. Demodex mites (tiny organisms that live in eyelash follicles) are a common cause of blepharitis in adults.

Treatment: Daily lid hygiene, warm compresses, and in-office IPL therapy to address inflammation and Demodex. More on home care: Home Remedies for Dry Eyes.

Allergies

Seasonal and environmental allergies cause eye redness, itching, and watering — symptoms that overlap significantly with dry eye. Allergic inflammation can also damage the tear film and worsen existing dry eye. Many patients have both conditions simultaneously. Related: Can Allergies Really Cause Dry Eyes?

What you can do: Manage allergies with antihistamine drops (not oral antihistamines, which can worsen dry eye). Cool compresses can soothe acute symptoms. If both allergies and dry eye are present, your optometrist can help manage both without treatments that conflict.

LASIK and Eye Surgery

LASIK and other corneal refractive surgeries temporarily disrupt the corneal nerves that signal tear production. Most patients experience dry eye symptoms for 3–6 months post-surgery, and for some, it can persist longer. Cataract surgery can also cause temporary dryness.

What you can do: If you are considering LASIK, get a dry eye assessment beforehand — pre-existing dry eye should be treated before surgery. Post-surgical dry eye is typically managed with preservative-free drops and, if needed, prescription anti-inflammatory drops.

Autoimmune Conditions

Certain autoimmune diseases — particularly Sjögren’s syndrome, rheumatoid arthritis, and lupus — can cause aqueous-deficient dry eye by attacking the lacrimal glands. If you have unexplained severe dry eye alongside dry mouth, joint pain, or fatigue, your optometrist may recommend testing for underlying autoimmune conditions.

Treatment: Autoimmune-related dry eye typically requires prescription drops (cyclosporine or lifitegrast) for long-term inflammation control, alongside punctal plugs and artificial tears.

Nocturnal Lagophthalmos (Dry Eyes at Night)

Some people sleep with their eyes slightly open without realizing it — a condition called nocturnal lagophthalmos. This exposes the eye surface to air overnight, causing significant dryness and irritation upon waking. Read more: Dry Eyes at Night.

What you can do: Use a thick, gel-based lubricant before bed. A moisture chamber sleep mask can also help. If the problem persists, talk to your optometrist about nighttime treatment options.

What Should You Do About Your Dry Eyes?

If your eyes are persistently dry, gritty, tired, or irritated, the most important step is getting a proper diagnosis. Dry eye has many causes — often more than one at a time — and the right treatment depends entirely on what is driving your symptoms.

At Garibaldi Eye Care, your eye doctor in Squamish, BC, we use advanced diagnostic tools (InflammaDry, osmolarity testing, meibography) to identify your specific type of dry eye and build a targeted treatment plan. Book your dry eye assessment

In the meantime, you can start with some simple relief strategies: Home Remedies for Dry Eyes and our recommended eye drops.

Frequently Asked Questions

What is the most common cause of dry eyes?

Meibomian gland dysfunction (MGD) is the most common cause, accounting for roughly 85% of dry eye cases. The oil glands in the eyelids become blocked or dysfunctional, causing tears to evaporate too quickly.

Can dry eyes be caused by too much screen time?

Yes. Screen use reduces your blink rate by up to 60%, which causes tears to evaporate faster. This is one of the most common triggers for dry eye symptoms, especially in people who work on computers for long hours.

Do allergies cause dry eyes?

Allergies can cause symptoms that mimic dry eye (redness, itching, watering) and can also worsen existing dry eye by inflaming the eye surface. Many patients have both conditions. More details here.

Can medications cause dry eyes?

Yes. Antihistamines, decongestants, antidepressants, blood pressure medications, and isotretinoin (Accutane) are common culprits. Talk to your prescribing doctor if you suspect a medication link — do not stop taking medication without medical advice.

When should I see a doctor for dry eyes?

If your symptoms have lasted more than a few weeks, are getting worse, or are affecting your daily activities (reading, driving, screen work), see a Squamish optometrist. Dry eye is progressive, and earlier treatment leads to better outcomes. Book an assessment at Garibaldi Eye Care.