What Causes Dry Eye Syndrome?
If you find yourself rubbing your eyes due to discomfort, excess watering, or blurred vision, your eyes may be trying to tell you something. According to the National Eye Institute, nearly 16 million Americans experience these symptoms due to dry eye syndrome, a condition that causes a breakdown in the tear film (the thin fluid layer on the surface of the eye).
While common and often chronic, dry eye is a treatable condition and there are many therapeutic options available to provide you with relief. Below, we explain what causes dry eye, who is most at risk for dry eye syndrome, and the various treatment options available.
How Tears Work
To understand dry eye syndrome, you must first understand how tears work. Each time you blink, the eyes produce tear film to keep the front surface of the eye, known as the cornea, smooth and clear.
Tears consist of three layers: an outer oily layer, a middle watery layer, and an inner mucus layer.
Outer oily layer: Produced by your meibomian glands along the edge of the eyelids, this layer keeps the cornea smooth and shields the inner watery tear layer from drying out.
Inner watery layer: Produced from your eyelids’ lacrimal glands, this watery layer of fluid serves as protection by washing particles away to keep the eye clean. The fluid helps reduce the risk of eye infections and also keeps the cornea lubricated and moist.
Inner mucus layer: Produced in the conjunctiva, mucus helps tears spread and stick to the eye. This clear layer covers the white part of the eye and inside of the eyelids.
In the event your eyes produce more tears than normal, such as when crying or due to an irritant, the excess tears drain into small ducts in the corners of your eyelids before traveling to the back of the nose.
What Is Dry Eye Syndrome?
In a normal eye, the production and drainage of tears are not a problem. But, for some people, this balance is off, leading to dry eye syndrome. Dry eye can also mean your eyes are not producing the right type of tears or any of the three tear layers may be inadequate or unstable.
The result of this imbalance can produce the following symptoms:
- Irritated, gritty, scratchy, or burning eyes
- A feeling of something in your eye
- Excess watering
- Blurred vision
- Mucus strings near your eye
- Pain when wearing contact lenses
The name “dry eye” can be confusing since your eyes may still water with this condition. This is because neurotransmitters signal the eyes to produce tears to counteract irritation or inflammation.
To diagnose dry eye, your eye doctor can perform several tests during a comprehensive eye exam. First, they will chart your medical history for possible risk factors. As part of the physical exam, they may view your eyelids and the surface of your eye, your blinking patterns, and how you produce tears.
The Schirmer test uses blotting strips of paper under your lower eyelids to measure tear volume. Your doctor can also use eye drops with a special dye to analyze the drainage and evaporation process. Additionally, a tear osmolarity test measures the salt concentration of your tears with higher levels of salt indicative of dry eye.
What Can Cause Dry Eye?
If you experience dry eye syndrome, it means your glands do not produce enough tears, your tears evaporate too fast, or the quality of your tears does not keep the eyes lubricated and nourished.
There are several factors that can cause these issues, ranging from your age and gender to environmental factors and health conditions. Long-term contact lens use and LASIK surgery to correct refractive errors can decrease tear production, although symptoms from LASIK are generally not long-lasting.
Meibomian Gland Dysfunction
The most common dry eye culprit is a blockage of oil glands in your upper and lower eyelids. More specifically, the meibomian glands produce oils that make up your outer tear layer. This layer prevents the inner watery layer from evaporating too quickly. In dry eye patients, a condition called meibomian gland dysfunction (MGD) results in blocked, damaged, or malfunctioning glands.
Age and Gender
Tear production decreases as you age due to eyelid lowering that can expose the cornea. If you are older than 65, talk to your eye doctor about dry eye. This is the age when people tend to experience dry eye the most. Gender also plays a role, as women are more likely to develop dry eye due to hormonal changes during pregnancy or menopause.
Certain medications can cause a decrease in tear production. Talk to your doctor about any medications you are taking. This includes over-the-counter drugs, as antihistamines and decongestants in allergy or cold medications can cause dry eye.
Many common prescription medications also may heighten your risk of developing dry eye. Examples include antidepressants and prescriptions for blood pressure, acne, and birth control. Preservatives in eye drops may also prove to be counterproductive and make your tears evaporate too quickly.
Living in climates with excess wind or dry air may increase tear evaporation. Low humidity, allergens, or smoke associated with certain occupations can also cause tears to evaporate.
If you have rheumatoid arthritis, diabetes, or thyroid problems, you are more at risk of developing dry eye. Autoimmune diseases, such as lupus or Sjögren syndrome, are also known to cause dry eye. Additionally, inflammation of your eyelids or the surface of your eye can lead to dry eye, as can eyelids that turn outward (ectropion) or inward (entropion).
Not Blinking Enough
Not blinking enough leads to lower tear film, thus resulting in dry eye. This may happen due to a medical condition, such as Parkinson’s disease, where the blink rate decreases. Common visual activities, such as reading or staring at a computer screen for too long at work, can also lead to a low blink rate.
How to Get Rid of Dry Eye
Dry eye is a chronic condition that requires lifestyle changes or medical treatment in the form of medication or therapeutic procedures.
For most people with mild dry eye syndrome, artificial tears are a common treatment option that mimics your natural tears. Artificial tears can be purchased over the counter. Use them on an as-needed basis.
Here are a couple notes to consider: Artificial tears come in drops, gels, or ointments. Gels and ointments are thicker and therefore last longer, but use them at night to avoid clouded vision. Choose preservative-free artificial tear solutions, as they are gentler on the eye and may help more with symptom relief. Stay away from redness-reducing drops since long-term use can cause irritation.
Inflammation near your eyelids or on your cornea can keep oil glands from secreting oil into your tears. Taking oral antibiotics can help control inflammation near your eyelids, while prescription corticosteroid eye drops can help alleviate cornea inflammation. However, long-term corticosteroid use is not recommended.
Prescription Eye Drops
A number of prescription eye drops, called cholinergics, help stimulate secretions in your eyes to increase tear production. Your doctor can also prescribe them in pill form or as a gel.
Your eyes have tiny openings in them, called puncta, that assist in the drainage of tears. To help treat dry eye, your doctor can insert a punctual plug to conserve your tears. The plug is the size of a grain of rice and made from acrylic, silicone, or collagen. Collagen plugs are temporary and gradually dissolve in as quickly as a few days or as long as a few months. Temporary plugs are common after LASIK, as dry eye is a common side effect of laser surgery. Semi-permanent plugs made from silicone or acrylic last for years, and an ophthalmologist will need to remove them.
LipiFlow is an FDA-approved treatment for MGD that warms and massages the inside of the eyelids to improve how oil flows from the meibomian glands. These oils keep the tears from evaporating too quickly, which helps keep the surface of the eye healthy.
The procedure lasts about 12 minutes and can take up to six to eight weeks for optimal results. Relief from dry eye with LipiFlow can last up to a year.
Intense Pulsed Light (IPL)
A procedure called intense pulsed light (IPL) can be used to clear blockages in the meibomian glands by using short bursts of light to heat the skin around the meibomian glands and increase oil production.
While wearing protective shields over your eyes, your eye doctor will use a handheld device that emits light to specific areas of the eyelids. The oil will then be manually expressed from your glands. In total, you will receive four treatments over four months. Upon completion of the initial treatments, you will then receive follow-up IPL treatments every six months to a year depending on your condition.
Specialty Contact Lenses
In certain cases of severe dry eye, scleral lenses (larger specialty contact lenses that do not touch the cornea) can help trap moisture.
Dry Eye Prevention at Home
Sometimes, it is best to treat the underlying cause of dry eye instead of the actual symptoms. For example, if a medication is the culprit, consider asking your doctor if you can switch to a different drug.
You can also take measures to limit the severity of symptoms. Avoid exposing your eyes to heat or dry air, such as a hair dryer, for prolonged periods of time. You might also consider adding a humidifier to your home to increase moisture levels during the winter. In windy climates, such as Oklahoma, wear glasses outside to protect your eyes from airborne particles.
You may also consider a diet modification to add omega-3 fatty acids to your meals. Omega-3 is found in oily fish and certain nuts and seeds, such as flaxseed, chia seeds, and walnuts. If dietary restrictions preclude you from eating foods containing omega-3, a fish oil supplement might be an option.