What Is Dry Eye Syndrome?

Dry eye syndrome is a chronic condition in which your eyes lack proper lubrication. Other terms for dry eye syndrome include:

• Dry eye
• Dry eye disease
• Keratoconjunctivitis sicca 

You can have dry eyes when your eyes do not make sufficient amounts of tears, or when your tears are of poor quality. A healthy tear film is important because your tears flush out irritants, protect from eye infections, help you see clearly, and lubricate your eyes.

Your tear film consists of three layers:

• Mucin (mucous) layer is the first layer closest to your eye. The mucous coating helps spread tears across your eye each time you blink. Goblet cells in your conjunctiva, which is the layer of tissue covering the whites of your eye, produce the mucin layer.
• Aqueous (water) layer is the most substantial layer of your tear film. This water layer helps moisturize your eyes and maintains clear vision. The lacrimal glands, which sit behind the outer part of your eyebrow, produce the aqueous layer.
• Lipid (oil) layer is the outer layer of your tears. An oil layer is essential because it keeps the aqueous layer from evaporating quickly. The glands along your eyelid margins, called Meibomian glands, produce the oil.

Each time you blink, your eyelids help distribute a fresh layer of tears across your eye. However, if there is a deficiency in any of these layers of the tear film, you can have dry eyes.

Types of Dry Eye

Dry eye is categorized based on the affected tear film layer: 

Aqueous Deficient Dry Eye

This is when your lacrimal glands do not produce enough of the aqueous layer of tears. This type is less common and usually affects people with underlying systemic conditions, which we will review below.

Evaporative Dry Eye

This occurs when you do not have a sufficient lipid layer in your tear film, causing the aqueous layer to evaporate. This form of dry eye is most common and occurs when your Meibomian (oil) glands are clogged. People with rosacea may be prone to evaporative dry eye.

Symptoms

Dry eye syndrome affects a large percentage of the population. These percentages are likely to increase, considering the frequent use of digital devices, which can aggravate dry eyes.

Studies estimate that approximately 7 to 33% of people have dry eye symptoms. 

Physical symptoms of dry eye syndrome include:

• Burning 
• Itching
• Heavy or sore eyes
• Foreign body sensation (can feel like an eyelash is in your eye)
• Discharge
• Redness
• Tearing
• Eye pain

Visual symptoms of dry eye syndrome include:

• Blurry vision 
• Light sensitivity
• Glare

Causes 

Several factors can influence your risk for dry eyes. Generally, women and older people are more likely to develop dry eye syndrome.

• Older age. Your tear production declines with age. In women, hormonal changes that occur with menopause negatively affect tear secretion. In men, a decline in androgen levels with age can cause a decrease in tear production.
• Female gender. Menopausal and post-menopausal women have a higher risk of dry eyes.
• Environment and climate. Sunny or windy conditions can trigger dry eyes. Pollution, pollen, dust, and other environmental irritants can also aggravate symptoms. People living in dry climates are generally more prone to dry eye than those living in humid climates.
• Digital devices. Blinking helps your eyes distribute fresh tears. However, most people who use a computer, tablet, or phone do not blink frequently enough while using their device. This causes your eyes to dry out faster.
• Contact lenses. Contact lenses affect the quality of your tear film, restrict oxygen and tear flow, and can trap allergens and irritants in your eye. All of these factors can aggravate dry eyes.
• Medications. There are several classes of drugs that can cause dry eyes. Some drugs include blood pressure medication, allergy (antihistamine) medication, antidepressants, antipsychotics, decongestants, hormonal therapies, diuretics, sedatives, and retinoids (such as Accutane).
• Systemic conditions. Sjogren's Syndrome is an autoimmune disease that causes dry eyes and dry mouth. Rheumatoid arthritis, lupus, diabetes, and thyroid problems are other conditions frequently associated with dry eye syndrome.
• Eye surgery. Laser eye surgery (such as LASIK) and cataract surgery can disrupt the tear film. Post-surgical dry eye is common and may be temporary or long-lasting. 

Treatment Options for Dry Eye Syndrome

There are a variety of treatments for dry eye, depending on the severity of the disease. Some at-home therapies include:

• Lubricating drops, also called artificial tears, provide extra moisture for your eyes. There are many over-the-counter options to choose from, including gel eye drops, oil-enriched eye drops, preservative-free eye drops, and nighttime ointments. Your eye doctor can recommend a specific type depending on the severity and type of dry eye you have.
• Heat compresses are helpful for clogged Meibomian glands. Clogged glands can lead to a deficiency in the lipid layer of your tear film. The heat, along with a gentle eyelid massage, encourages the oil glands to open up. Your eye doctor can examine your eyes to check for clogged Meibomian glands.
• Omega-3 fatty acid supplements, such as fish oil or flaxseed oil, have anti-inflammatory properties. Since dry eye syndrome is considered an inflammatory condition, some research suggests taking omega-3 supplements may improve symptoms.

There are also prescription medications or in-office treatments your eye doctor can use to treat dry eye:

• Meibomian gland expression is an in-office procedure your eye doctor can perform to unclog your oil glands if the heat compresses do not help.
• Punctal plugs are plugs your eye doctor can place into your puncta, which are the small holes in your eyelids that drain tears out of your eyes. The plug will slow down tear drainage, allowing more tears to stay on the surface of your eyes. Punctal plugs are available in a collagen material, which are temporary and dissolve after a few months. They also come in a semi-permanent silicone material, which your eye doctor can remove if they irritate your eyes.
• Corticosteroid eye drops are anti-inflammatory drops that can improve dry eye symptoms. Because corticosteroids can increase your risk of cataracts and glaucoma, most doctors only use this as a short-term treatment.
• Immunomodulatory drugs are medications that change your body’s immune response. Cyclosporine (brand name Restasis) and lifitegrast (brand name Xiidra) are two eye drop medications in this class of drugs. They work by reducing inflammation associated with dry eyes and stimulating your eyes to produce more tears.

Can Dry Eye Syndrome Cause Blindness?

Dry eye rarely causes blindness. However, in cases of severe dry eye disease, patients can experience significant pain and blurry vision. 

Your cornea, the clear covering over your eye, is a delicate tissue filled with nerves. Good corneal health is essential for clear vision. Severe dry eye syndrome can damage the cornea, which is why you have symptoms of pain and blurry vision. If left untreated, permanent scarring of the cornea and vision loss can occur.

In addition to the therapies listed above, severe dry eye may also be treated with:

• Autologous serum eye drops are eye drops made with your blood. The components of this serum are naturally found in your tears and promote healing. Autologous serums are usually reserved for severe dry eye disease where the surface of the eye is damaged.

• Amniotic membranes are made from the placental tissue of female donors after they give birth. In a simple in-office procedure, your eye doctor places the membrane onto your cornea. The amniotic membrane serves as a biologic bandage that promotes corneal healing and reduces inflammation.