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10 Causes of Dry Eye that You Might not Know About

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What Really Causes Dry Eye?

Dry eye is ultimately due to 2 factors: low tear quality or low tear quantity. Without the right amount of tears or without the right tear composition, your eyes will ultimately end up feeling dry and irritated. A number of factors can cause dry eye. You might be familiar with some of the well-known causes like contact lenses, but you might not know how many other factors can lead to dry eye.

Antihistamines & Decongestants

Antihistamines and decongestants may help relieve your allergy and cold symptoms, but they could be causing your dry eye symptoms. Antihistamines block common allergy symptoms like itching, sneezing, runny nose, and watery eyes. To prevent watery eyes, antihistamines cause your eyes to make fewer tears. Fewer tears can eventually lead to dry eye.

Decongestants can cause a similar problem. When you have the flu or a cold, decongestants help reduce congestion by increasing the room for airflow in your nose. They do this by reducing the swelling of blood vessels in nasal passages. But like antihistamines, decongestants can cause your eyes to make fewer tears, leading to dry eye.

Prescription Medications

A variety of prescription medications can lead to dry eye.

Acne Medication

Many acne medications, like isotretinoin (commonly known as Accutane), work by reducing the amount of oil produced by certain glands. These glands can be found throughout your body, including in your eyelids. If your tears donít have enough oil, it can lead to dry eye.

Sleeping Pills, Antidepressants, & Parkinsonís Medication

While sleeping pills, antidepressants, and Parkinsonís medication might not seem like they have a lot in common, they all work by blocking signals between nerve cells. This can be helpful in treating insomnia, depression, anxiety, and neurological conditions like Parkinsonís. 

However, these types of medications can also block the signals that tell your eyes itís time to produce more tears. If you are experiencing dry eye as a side effect of a medication, you can talk to your doctor about adjusting your dose. Your optometrist may also be able to recommend a dry eye therapy option like medicated eye drops to provide you with relief. 

Nutrient Deficiency

Lack of vitamin A is associated with a number of eye issues, including dry eye. Vitamin A is very important for vision and overall eye health. Vitamin A deficiency is not very common in Canada and is usually only seen in people who are severely malnourished. 

Omega 3 fatty acids can also help with dry eye disease. Omega-3 supplements or increasing consumption of foods containing omega-3ís is often recommended to dry eye patients.

Hormonal Changes

In general, dry eye is more common in women, especially ageing women. For many women, their dry eye has a hormonal component, including menopause, hormone replacement therapy, or birth control.

The relationship between hormonal changes and dry eye isnít fully understood, but some believe that hormones impact how much water goes into tears. The hormone estrogen seems to have a particularly strong effect on tear levels and dry eye. One study saw a 69% increase in dry eye in women taking estrogen hormone replacement therapy compared to women who werenít taking any hormones.


Rosacea is a common skin condition that causes facial redness. For some people, rosacea can affect their eyes as well as their skin. Up to 70% of rosacea patients will have some kind of ocular issue, including meibomian gland dysfunction. 

Meibomian gland dysfunction is a condition that prevents the oil glands on your eyelid from working properly. Without proper gland function, your tears wonít contain enough oil, which can cause dry eye. Meibomian gland expression is one way your optometrist can address meibomian gland dysfunction.

Autoimmune Disease

One autoimmune disease that causes dry eye is Sjogrenís syndrome. This condition causes dry eye and dry mouth by targeting the glands that produce tears and saliva. Other autoimmune conditions can cause dry eye as well, although the exact reason isnít fully understood.

Autoimmune diseases like lupus, rheumatoid arthritis, and scleroderma can all cause dry eye. Some believe that the relationship between these autoimmune diseases and dry eye is due to inflammation. Autoimmune diseases cause your immune system to attack healthy tissue, which causes inflammation. This inflammation can damage tear glands and oil glands, leading to dry eye.

Entropion & Ectropion

Problems with your eyelids can lead to dry eye by preventing your eyelids from closing completely. Entropion (when your eyelids turn inwards) and ectropion (when your eyelids turn outwards) are two conditions that can prevent your eyelids from closing properly. Certain types of facial paralysis, like Bellís Palsy, can cause the same problem. By preventing the eyelids from closing completely or properly, tears will evaporate, leading to dry eye.

Computer Use

A common symptom of computer vision syndrome or digital eye strain is dry eye. When we do a lot of close work, like using the computer, we donít blink as often as we normally would. Less blinking can dry out the eye. 

Another factor that can contribute to dry eye is the repeated horizontal eye movements we make when using computers. Looking back and forth horizontally can irritate spots on our eyes that are already dry, worsening dry eye symptoms. If you have dry eye from computer use, it could be helpful to follow the 20-20-20 rule by taking a break every 20 minutes to look at something 20 feet away for 20 seconds. 

Climate Control

Artificial heating and cooling can contribute to dry eye symptoms. Air conditioning is especially bad as it removes moisture from the air. Central heating doesnít help much either. If you notice dry eye symptoms from climate control, you might want to consider turning down your AC or furnace if you can. You may also find it helpful to use a humidifier and make sure your workspace isnít directly underneath or next to a heating vent.

Environmental Factors

Factors outside your home can contribute to dry eye as well. Smoke, wind, and lack of humidity can all cause dry eye symptoms. If you notice that your eyes are very itchy and your symptoms worsen when you go outside, your dry eye could be due to allergies from environmental allergens like pollen. Your optometrist will be able to help determine the exact cause of your dry eye and the appropriate treatment.

Whatever the cause, a comprehensive eye exam from an optometrist is the best way to determine the culprit of your dry eye. A thorough dry eye evaluation will allow your optometrist to determine the root cause of your dry eye as well as the appropriate dry eye treatment.

Written by Dr. Asim Prasad

Dr. Asim Prasad is a native Calgarian who earned his Bachelorís of Science degree in Vision Science and Doctor of Optometry degree from Nova Southeastern University in Ft. Lauderdale, Florida in 2008. Before becoming an optometrist, Dr. Prasad earned a bachelorís degree in Environmental Science from the University of Alberta. After working in the environmental science industry for a short time, Dr. Prasad decided to pursue his true passion: optometry.
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