Understanding Dry Eye: Causes and Treatment

Dry eye disease is a common and often chronic condition that occurs when your tears are unable to provide adequate lubrication for your eyes. 

This tear film instability can lead to inflammation, discomfort, and in some cases, vision problems.

Affecting an estimated 16 million diagnosed Americans, with millions more likely undiagnosed, dry eye syndrome is far more than a minor annoyance.

It’s a complex medical condition that can significantly impact one’s quality of life.

This comprehensive guide will delve into the science behind dry eyes, explore the myriad of symptoms and causes and detail the full spectrum of treatments available today.

What is Dry Eye Disease (DED)?

While the term “dry eyes” seems self-explanatory, the clinical reality is much more nuanced.

It’s not just about a lack of moisture, it’s about the quality, stability, and function of the entire tear system.

Understanding this complexity is the first step toward effective management.

The Official Definition: Beyond Just Dryness

In 2017, the Tear Film & Ocular Surface Society (TFOS) released its landmark Dry Eye Workshop II (DEWS II) report, which provided a globally recognized, evidence-based definition of the condition.

This definition is crucial because it frames dry eye as a multifaceted disease.

“Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.”
– TFOS DEWS II Report

Let’s break this down:

• Multifactorial disease: It has many contributing causes, not just one.
• Loss of homeostasis: The stable, balanced environment of the eye’s surface is disrupted.
• Tear film instability: Tears evaporate too quickly or don’t spread evenly.
• Hyperosmolarity: The tears become too salty, which damages surface cells.
• Inflammation and damage: This is both a cause and a result of dry eye, creating a vicious cycle.
• Neurosensory abnormalities: The nerves in the eye can become damaged or overly sensitive, leading to pain even when the eye doesn’t look severely dry.

Understanding the Tear Film: Your Eye’s Protective Shield

To understand dry eye, you must first appreciate the tear film. It’s not just salty water.

This highly structured, microscopic liquid layer covers your cornea and has three distinct layers, each with a critical job.

1. The Lipid (Oil) Layer: The outermost layer, produced by the meibomian glands in your eyelids. Its primary function is to create a smooth surface for light to enter the eye and, most importantly, to prevent the watery layer below from evaporating too quickly.
2. The Aqueous (Water) Layer: The middle and thickest layer, produced by the lacrimal glands. This is the “watery” part of the tear that provides moisture, delivers oxygen and nutrients to the cornea and washes away debris and pathogens.
3. The Mucin (Mucus) Layer: The innermost layer, produced by goblet cells in the conjunctiva (the clear tissue covering the white of your eye). This sticky layer helps the aqueous layer adhere and spread evenly across the eye’s surface.

A problem with any of these three layers can disrupt the tear film’s homeostasis and lead to dry eye disease.

The Two Main Types of Dry Eye Disease

Based on which part of the tear film is dysfunctional, dry eye is broadly classified into two main categories, though many people have a combination of both (mixed-mechanism).

Type of Dry Eye	Primary Problem	Key Characteristics	Common Causes
Aqueous Deficient Dry Eye (ADDE)	Not enough water is produced.	The lacrimal glands fail to produce a sufficient volume of the aqueous layer. This accounts for about 10% of dry eye cases.	Sjögren’s syndrome, other autoimmune diseases (lupus, rheumatoid arthritis), aging, lacrimal gland damage.
Evaporative Dry Eye (EDE)	Tears evaporate too quickly.	The most common form of dry eye. There may be enough water, but a deficient lipid layer allows it to dry out before the next blink.	Meibomian Gland Dysfunction (MGD), infrequent blinking (screen use), environmental factors (wind, low humidity), contact lens wear.

What Are the Symptoms of Dry Eyes?

The symptoms of dry eye can vary widely from person to person and can range from mildly annoying to debilitating.

They usually affect both eyes. Recognizing the full range of symptoms is key to seeking timely diagnosis and treatment.

• A stinging, burning, or scratchy sensation in your eyes.
• A feeling of grittiness, or like there is sand or something foreign in your eye.
• Strings of mucus in or around your eyes.
• Eye redness and irritation.
• Increased sensitivity to light (photophobia).
• Difficulty wearing contact lenses.
• Eye fatigue, especially after reading or using a computer.
• Blurred vision that often improves temporarily after blinking.
• Difficulty with nighttime driving.

The Paradox of Watery Eyes: When Dry Eyes Aren’t Dry

One of the most confusing symptoms of dry eye is excessive tearing, a condition known as epiphora.

It seems counterintuitive, but it’s a key sign of the disease.

When the eye’s surface becomes overly dry and irritated, the nervous system sends a distress signal to the lacrimal gland, which responds by flooding the eye with a large volume of emergency tears.

However, these “reflex tears” are mostly water and lack the balanced composition (especially the oil and mucus layers) of normal tears.

They don’t lubricate the eye effectively and quickly run off the surface, leaving the underlying problem of dryness unresolved.

How Dry Eye Impacts Daily Life and Mental Well-being

The impact of moderate to severe dry eye extends far beyond physical discomfort.

Studies have shown that DED can significantly decrease a person’s quality of life.

The constant irritation and visual disturbances can make essential daily activities challenging.

“Crucial daily activities of modern living such as reading, computer use, professional work, driving, and TV watching are all negatively impacted by DES.” – Impact of Dry Eye Syndrome on Vision-Related Quality of Life, 2007

This daily struggle can lead to frustration, anxiety and even depression.

The condition’s chronic nature and the trial-and-error process of finding effective treatments can take a significant emotional toll.

As noted by the Cleveland Clinic, dry eye can affect your ability to work, socialize, and enjoy life, making it a serious health concern.

What Causes Dry Eyes?

Dry eye is a multifactorial disease, meaning a combination of factors often contributes to its development.

These can be broken down by the type of dry eye they primarily cause, as well as general risk factors that increase your likelihood of developing the condition.

Aqueous Deficient Dry Eye (ADDE) Causes

This “not enough tears” type of dry eye is often linked to systemic health issues or age-related changes.

• Sjögren’s Syndrome: An autoimmune disease where the body’s immune system mistakenly attacks its own moisture-producing glands, including the lacrimal (tear) and salivary (saliva) glands. This is a classic cause of severe ADDE.
• Other Autoimmune Diseases: Rheumatoid arthritis, lupus, and scleroderma can also be associated with decreased tear production.
• Aging: Tear production naturally tends to diminish as we get older, particularly after age 50.
• Lacrimal Gland Damage: Injury, inflammation, radiation, or infiltration of the tear glands can impair their ability to produce the aqueous layer.
• Corneal Nerve Desensitivity: Long-term contact lens use or nerve damage from surgeries like LASIK can reduce the signals that tell the lacrimal gland to produce tears. (Symptoms from LASIK are often temporary).

Evaporative Dry Eye (EDE) Causes

This “poor quality tears” type is the most common form of DED and is often related to eyelid health and environmental factors.

• Meibomian Gland Dysfunction (MGD): This is the leading cause of EDE. The tiny oil glands (meibomian glands) along the edges of the eyelids become clogged or blocked, preventing them from secreting the essential lipid layer into the tear film.
• Infrequent Blinking: When we concentrate on digital screens, reading, or driving, our blink rate can decrease by more than 50%. Blinking is essential for spreading tears and stimulating the meibomian glands.
• Eyelid Problems: Conditions like blepharitis (eyelid inflammation), or anatomical issues where the eyelids turn inward (entropion) or outward (ectropion), can affect tear distribution and gland function.
• Environmental Factors: Exposure to wind, smoke, and dry climates (airplanes, air-conditioned rooms, desert areas) accelerates tear evaporation.
• Vitamin A Deficiency: While rare in developed countries, a lack of Vitamin A is essential for a healthy ocular surface and can cause severe dry eye.

Common Risk Factors You Should Know

Certain factors make it more likely that you’ll experience dry eyes:

• Age: Being over 50 is a major risk factor.
• Gender: Women are more commonly affected, especially due to hormonal changes associated with pregnancy, birth control pills and menopause.
• Medications: A wide range of common medications can reduce tear production.
• Medical Conditions: Beyond autoimmune diseases, conditions like thyroid disorders and diabetes are linked to dry eye.
• Contact Lens Wear: Long-term use can contribute to both EDE and ADDE.
• Refractive Surgery History: Procedures like LASIK can induce or worsen dry eye, though it’s often temporary.
• Diet: Diets low in omega-3 fatty acids (found in fish, walnuts) and Vitamin A may increase risk.

Medication Category	Examples	How They Can Cause Dry Eye
Antihistamines & Decongestants	Diphenhydramine (Benadryl), Loratadine (Claritin), Pseudoephedrine (Sudafed)	Designed to dry up mucus membranes, which also reduces tear production.
Antidepressants & Anti-Anxiety Meds	SSRIs (Prozac, Zoloft), Tricyclics (Elavil), Benzodiazepines (Xanax)	Many have anticholinergic effects that decrease secretions, including tears.
Blood Pressure Medications	Diuretics (“water pills” like HCTZ), Beta-blockers (Metoprolol)	Diuretics reduce fluid in the body, beta-blockers can decrease tear production.
Hormone Replacement Therapy (HRT)	Estrogen-based therapies	Hormonal fluctuations can alter tear film composition and stability.
Acne Medications	Isotretinoin (formerly Accutane)	Known to cause severe atrophy of the meibomian glands, leading to chronic EDE.

How Is Dry Eye Syndrome Diagnosed?

A proper diagnosis is critical for effective treatment.

Because dry eye is multifactorial, your eye doctor will use a combination of methods to understand the specific cause and severity of your condition.

A comprehensive eye exam for dry eye goes far beyond a simple vision check.

The Role of Your Eye Doctor

Both Ophthalmologists (medical doctors, M.D., who perform surgery) and Optometrists (doctors of optometry, O.D.) are qualified to diagnose and treat dry eye disease.

Many optometrists now specialize in dry eye management and offer advanced diagnostic and treatment technologies.

Starting with Your Symptoms: Questionnaires and History

Your visit will almost always begin with a detailed discussion of your symptoms, general health, medications and lifestyle.

You may be asked to fill out a standardized questionnaire to quantify your symptoms, such as:

• Ocular Surface Disease Index (OSDI): A 12-item questionnaire that scores symptoms, their impact on vision-related functions (like reading and driving) and environmental triggers.
• Standard Patient Evaluation of Eye Dryness (SPEED): A shorter questionnaire that helps assess the frequency and severity of symptoms.

In-Office Diagnostic Tests Explained

After discussing your symptoms, your doctor will perform several painless tests to evaluate your tears and ocular surface.

• Slit-Lamp Examination: Using a high-magnification microscope, the doctor will examine your eyelids, lashes, conjunctiva, and cornea. They will look for signs of inflammation, blepharitis and MGD (e.g., by gently pressing on the eyelids to check the quality of meibomian gland secretions).
• Fluorescein Dye Staining: A harmless yellow-orange dye is placed in the eye. This allows the doctor to see any damaged or dry spots on the cornea, as these areas will stain.
• Tear Break-Up Time (TBUT): This is one of the most common tests for tear stability. After applying fluorescein dye, the doctor measures the time (in seconds) it takes for the first dry spot to appear on the cornea after a blink. A TBUT of less than 10 seconds is generally considered indicative of evaporative dry eye.
• Schirmer’s Test: This test measures the quantity of aqueous tear production. A small strip of filter paper is placed inside the lower eyelid for five minutes. The doctor then measures the length of the strip that has been wetted by tears. This helps diagnose aqueous deficient dry eye.
• Tear Osmolarity Test: This advanced test measures the salt concentration of your tears. A higher-than-normal salt content (hyperosmolarity) is a key biomarker for dry eye disease, as it indicates that the aqueous component is evaporating too quickly.
• Meibomian Gland Imaging (Meibography): Specialized cameras use infrared light to take pictures of the meibomian glands inside the eyelids. This allows the doctor to see the structure of the glands and identify any atrophy or “dropout”, which is a definitive sign of MGD.

What is the Best Treatment for Dry Eyes?

There is no one-size-fits-all “cure” for dry eye, as it is typically a chronic condition.

However, a wide array of effective treatments can manage symptoms, protect the ocular surface and improve quality of life.

Treatment is usually approached in a stepwise manner, starting with simpler methods and progressing to more advanced therapies as needed.

Level 1: Lifestyle Modifications and At-Home Care

These foundational changes can make a significant difference for mild dry eye and are essential for supporting any advanced treatments.

• Blink Consciously: Remember to blink fully and frequently, especially during screen use. Follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for at least 20 seconds.
• Optimize Your Environment: Use a humidifier to add moisture to indoor air. Avoid direct exposure to fans, vents and wind. Wear wraparound sunglasses outdoors.
• Stay Hydrated: Drink plenty of water throughout the day.
• Dietary Adjustments: Increase your intake of omega-3 fatty acids. Sources include fatty fish (salmon, mackerel), flaxseeds, chia seeds and walnuts. Supplements may also be recommended by your doctor.
• Warm Compresses & Lid Hygiene: Applying a warm compress to the eyelids for 5-10 minutes can help melt the hardened oils in the meibomian glands. Following this with gentle eyelid massage and cleaning with a dedicated lid scrub can improve oil flow.

Level 2: Over-the-Counter (OTC) Solutions

For many, OTC products are the first line of defense for providing dry eye relief.

• Artificial Tears: These are lubricating eye drops designed to supplement your natural tears. The market is vast and finding the right one can take trial and error.
  • Preservative vs. Preservative-Free: Drops with preservatives have a longer shelf life but can cause irritation if used more than 4-6 times a day. Preservative-free drops, available in single-use vials, are recommended for frequent use or for those with sensitive eyes.
• Gels and Ointments: These are thicker than artificial tears and provide longer-lasting lubrication. Because they can cause temporary blurry vision, they are best used just before bedtime.

Level 3: Prescription Medications for Dry Eye Relief

When OTC treatments are not enough, your doctor may prescribe medications that target the underlying inflammation or stimulate tear production.

• Cyclosporine (Restasis®, Cequa®, Vevye®): These are immunomodulators that work by reducing the inflammation that interferes with tear production, thereby helping your body produce more of its own natural tears. It can take 3-6 months to notice the full effect.
• Lifitegrast (Xiidra®): This is another anti-inflammatory drop that works by blocking a specific protein on the cell surface involved in the inflammatory cycle of dry eye. It can provide relief more quickly than cyclosporine for some patients.
• Varenicline (Tyrvaya®): A novel approach, this is a nasal spray, not an eye drop. It works by stimulating a nerve in the nose that is part of the pathway controlling tear production, prompting the lacrimal gland to secrete more of the complete, multi-layered tear film.
• Topical Corticosteroids: Steroid eye drops may be prescribed for short-term use to quickly control a flare-up of inflammation. They are not intended for long-term use due to risks of side effects like increased eye pressure and cataracts.

Level 4: Advanced In-Office Procedures

For moderate to severe dry eye, particularly evaporative dry eye caused by MGD, your doctor may recommend specialized procedures.

• Punctal Plugs: Tiny, biocompatible plugs are inserted into the tear drainage ducts (puncta) in the corners of the eyelids. This acts like a stopper in a sink, keeping your natural tears on the eye’s surface for longer. They can be temporary (dissolvable) or semi-permanent (silicone).
• Thermal Pulsation (LipiFlow®): This FDA-approved device is considered a gold standard for treating MGD. It simultaneously applies heat to the inner eyelid and gentle pressure to express the blocked meibomian glands, clearing obstructions and restoring oil flow.
• Intense Pulsed Light (IPL) Therapy: Originally used in dermatology, IPL involves applying specific wavelengths of light to the skin around the eyes. This helps reduce inflammation, close off abnormal blood vessels that contribute to inflammation, and warm the meibomian glands.
• Meibomian Gland Probing: For severely blocked glands, a specialist may use a fine instrument to manually probe and open the orifices of the meibomian glands.

Level 5: Surgical and Specialized Interventions

In the most severe and refractory cases of dry eye, more advanced options may be considered.

• Autologous Serum Eye Drops: These are custom-made eye drops created from the patient’s own blood. The serum is rich in growth factors and nutrients that are very similar to natural tears and can help heal a damaged ocular surface.
• Scleral Lenses: These are large-diameter, rigid gas-permeable contact lenses that vault over the entire cornea and rest on the white part of the eye (the sclera). The space between the lens and the cornea is filled with a preservative-free saline solution, creating a constant liquid bandage that protects and hydrates the eye.
• Tarsorrhaphy: A surgical procedure where the eyelids are partially sewn together to narrow the eye opening and reduce the surface area exposed to air, thus decreasing tear evaporation. This is reserved for very severe cases.

Meibomian Gland Dysfunction (MGD): The Leading Cause of Dry Eye

It is impossible to have a complete discussion about dry eye without focusing on Meibomian Gland Dysfunction (MGD), as it is the root cause of the vast majority of cases.

According to the American Academy of Ophthalmology, MGD is a primary contributor to evaporative dry eye.

What is MGD and How Does It Cause Dryness?

Your eyelids each contain 20-40 tiny meibomian glands that produce the essential oil (meibum) for the tear film’s lipid layer.

In MGD, these glands become blocked. The meibum inside thickens, changing from a clear oil (like olive oil) to a thick, cloudy substance (like toothpaste). When this happens:

1. The lipid layer is not properly secreted onto the tear film.
2. Without its protective oil slick, the watery part of the tears evaporates up to 16 times faster.
3. The eye’s surface becomes dry and irritated, triggering the cycle of inflammation and symptoms.

If left untreated, the chronic blockage can cause the glands to atrophy and permanently die off, making the condition much more difficult to manage.

This is why early diagnosis and treatment of MGD are so critical.

Treating the Root Cause: MGD-Specific Therapies

While artificial tears can provide temporary relief, they are like putting a bandage on the problem.

MGD-focused treatments aim to restore the function of the glands themselves.

In addition to the in-office procedures like LipiFlow and IPL mentioned above, treatments may include:

• Prescription Medications: Topical antibiotics like Azithromycin can have anti-inflammatory effects and help improve the quality of meibum. Oral antibiotics like Doxycycline, used at a low dose, also act as powerful anti-inflammatory agents for the eyelids.
• Eyelid Debridement/Microblepharoexfoliation: A procedure where the doctor uses a specialized tool to mechanically remove bacterial biofilm and debris from the eyelid margins, which can contribute to MGD.

Can Dry Eyes Be Prevented?

While some risk factors like age and genetics cannot be changed, many lifestyle and environmental triggers can be managed to reduce your risk or prevent symptoms from worsening.

The Mayo Clinic offers several practical prevention strategies:

• Protect Your Eyes from Air: Avoid having hair dryers, car heaters, or fans blowing directly into your eyes.
• Position Your Computer Screen Correctly: Place your monitor below eye level. This causes you to open your eyes less widely, which slows tear evaporation.
• Take Regular Eye Breaks: During any task that requires visual concentration, close your eyes for a few minutes periodically or blink repeatedly for a few seconds to re-coat your eyes with tears.
• Stop Smoking and Avoid Smoke: Cigarette smoke is a major eye irritant and significantly worsens dry eye symptoms.
• Use Artificial Tears Proactively: If you know you’ll be in a dry environment (like an airplane), use lubricating drops before your eyes start to feel dry.

When Should You See a Dry Eye Specialist?

While your primary eye care provider can manage mild dry eye, you should consider seeing a specialist if:

• Your symptoms are persistent, severe, or worsening despite using OTC drops.
• Dry eye is significantly impacting your daily activities like reading, working, or driving.
• You have used multiple prescription drops without adequate relief.
• You suspect you may have an underlying condition like Sjögren’s syndrome or severe MGD.

A dry eye specialist will have access to advanced diagnostic tools (like meibography and osmolarity testing) and a wider range of in-office treatments (like LipiFlow and IPL) that may not be available at a general practice.

Frequently Asked Questions (FAQ) About Dry Eyes

1. Can dry eyes cause permanent vision loss?

While it is rare, severe, untreated dry eye can lead to complications like corneal ulcers, scarring and abrasion, which can cause permanent vision loss. For most people, however, dry eye primarily causes fluctuating blurry vision and discomfort rather than permanent damage.

2. What are the best eye drops for dry eyes?

The “best” drops are highly individual. For frequent use, preservative-free artificial tears are recommended. For MGD, drops containing lipids (oils) can be more effective. It’s best to consult your eye doctor for a personalized recommendation based on your specific type of dry eye.

3. Does drinking more water help dry eyes?

Yes, staying well-hydrated is important for overall health, including tear production. While it won’t cure dry eye on its own, dehydration can certainly worsen symptoms. It’s a crucial part of a holistic management plan for dry eye relief.

4. Can I wear contact lenses if I have dry eyes?

It can be challenging. Many people with dry eye find contacts uncomfortable. However, daily disposable lenses made from modern materials with high water content may be an option. Scleral lenses are a specialized option designed specifically for severe dry eye.

5. Is dry eye syndrome contagious?

No, dry eye syndrome is not contagious. It is a medical condition related to your tear film and ocular surface, not an infection that can be passed from person to person.

6. How long does it take for dry eye treatments to work?

It varies. Artificial tears provide immediate but temporary relief. Prescription drops like Restasis or Xiidra can take several weeks to months to show their full effect. In-office procedures like LipiFlow or IPL may also require time and multiple sessions for optimal results.

7. Can stress cause dry eyes?

While not a direct cause, stress can exacerbate dry eye symptoms. Stress can lead to inflammation throughout the body and may cause you to blink less or sleep poorly, all of which can worsen the condition.

8. Is there a permanent cure for dry eyes?

For most people, dry eye is a chronic condition that requires ongoing management rather than a one-time cure. However, with proper diagnosis and a consistent treatment plan, symptoms can be controlled very effectively, leading to significant long-term comfort and relief.

Medical Review

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for, and should never be relied upon for, professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.