What Causes Chronic Dry Eye and Who is at Risk?
Chronic dry eye has various causes and risk factors. Recognizing these helps to better understand how dry eye happens and who gets it most frequently.
What's the difference?
Causes and risk factors of a disease are sometimes used interchangeably, but there is a difference. Causes directly lead to a disease, while risk factors simply increase the likelihood of developing a disease. This means you can have risk factors, but you may not ever develop the disease.
However, chronic dry eye is a complex condition that has many causes that are not well understood. Because of this, “causes” and “risk factors” are often used together in describing certain conditions or factors that could result in dry eye.
Causes and risk factors of chronic dry eye
Normal aging puts older adults at an increased risk for developing chronic dry eye. Some research has shown that most adults over the age of 65 have experienced some type of dry eye symptoms.1
Chronic dry eye is twice as common in women than in men. More than 11 million American women have been diagnosed with chronic dry eye, compared to 5.3 million men. Researchers think that differences in hormone levels between men and women may be a reason. In women, hormonal changes from pregnancy, use of birth control pills, and menopause are also thought to play a role.1-3
Certain medicines may cause or increase the risk of developing chronic dry eye. Most research has studied classes or groups of drugs that may cause dry eye instead of individual medicines that may cause the disease. Some of these groups of drugs include:2,4
- Diuretics and beta-blockers – These are drugs that are often used to control blood pressure
- Antihistamines and decongestants – These are drugs that are used to help with seasonal allergy symptoms and to decrease swelling of the nose caused by upper respiratory conditions such as the common cold
- Sleeping aids – Some of these drugs have the same ingredients as allergy medicines
- Anti-anxiety and antidepressants – Drugs that are used to decrease anxiety or stabilize mood have been shown to increase the risk for chronic dry eye
- Proton pump inhibitors (PPIs) – Heartburn may occur in Sjogren’s syndrome, a common cause of chronic dry eye. Drugs used to treat this, known as PPIs, may increase the risk of developing dry eye.
- Retinoids – Accutane (a retinoid cream) is a drug used to treat acne that has also been linked to chronic dry eye
- Chemotherapy – Drugs used to treat cancer can cause poor healing to the surface cells of the cornea, called the epithelium
Conditions of the eyelid may lead to dry eye. Some of these include:5-7
- Blepharitis – Inflammation of the eyelids, causing red, swollen eyelids and crusty eyelashes. Some doctors think this may also be a result of dry eye but not necessarily a cause.
- Meibomian gland dysfunction – A blockage or abnormality of the meibomian glands of the upper or lower eyelid. These glands secrete the oily layer of the tear film, and, when they are not working properly, the tears may evaporate too quickly.
- Lagophthalmos – Incomplete closure of the eyelids when blinking or sleeping. This may be caused by aging, differences in anatomy from person to person, or as a result of cosmetic surgery to the eyelids or face.
Some medical conditions can cause or increase the risk of dry eyes. Many of these conditions are autoimmune diseases, where the body’s immune system attacks itself. Some of these include:7
Pollution, particles, and conditions in the environment can lead to dry eyes or worsen existing symptoms. These include:8
- Cigarette smoke
- Windy conditions
- Dry climate
- Air conditioner use
Any activity that requires prolonged focusing or unconsciously staring decreases the number of times you blink your eyes. With less blinking, the tear film does not refresh as often. Therefore, the surface of the eye is exposed longer as the tear film evaporates, which can lead to dry eyes. Increased screen time or computer use are examples of technology that can cause you to blink less frequently.9
Contact lens use
Up to half of all contact lens users stop wearing them within 3 years due to discomfort, with dry eye symptoms being 1 of the most common reasons. Contact lenses interfere with the tear film, and dry eye symptoms often get worse the longer a person wears contacts. Extended-wear contacts and sleeping in contacts may worsen dry eyes more so than daily contacts.9,10
Laser vision correction surgery
Laser vision correction surgeries such as LASIK and PRK can lead to symptoms of dry eye. These procedures change the shape of the cornea, which is the outer layer of the eye responsible for bending light for clear vision. These surgeries may also damage the nerves in the cornea. These changes can increase the risk for chronic dry eye.11,12
Electrolytes are elements, such as sodium and potassium, in the bloodstream that help maintain the balance of various functions within your body. When electrolytes are not at normal levels in the body, electrolytes in the tear film also become imbalanced. In particular, abnormal sodium levels in the tear film have been associated with chronic dry eye.13