Understanding Dry Eye Disease

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What Can Cause Dry Eye Symptoms?

The key to effective dry eye treatment is to understand the underlying cause of the symptoms.  Dry eye is generally caused by an imbalance of the tear film that acts as a shield on the surface of our eyes. There are two primary contributors to tear film imbalance.  The first is decreased tear production however, this is now thought to be less common than once believed. The second is considered to be a leading cause of dry eye and results from blockages in the tiny meibomian glands in the eye lids. These glands produce essential oils that form the top layer of the tear film and are the core protective element that is essential to long-term eye comfort.

When the Meibomian glands are blocked or the glands have been compromised, the eye surface becomes exposed and can lead to dry eye symptoms. This condition is known as Meibomian Gland Dysfunction (MGD).  If you have MGD, treatment is essential for the long-term management of dry eye.

Understanding the Tear Film

The tear film is a complex structure of mucin, tears and oil that protects the surface of the eyes. When the tear film is compromised, it results in a variety of symptoms, most of which have been associated with Dry Eye and MGD (Meibomian Gland Dysfunction). Understanding the tear film is key to seeing the clear differences between tear deficiency issues and MGD, especially since MGD is more common and has greater long term impact on Dry Eye symptoms.

Mucin Layer

The Sticky Foundation

The mucin (mucous) layer at the bottom of the tear film provides a “sticky” foundation and acts as a barrier to the eye surface.

Aqueous Layer

The Watery Center

The aqueous layer is the “juicy” center that is comprised of tears produced by the lacrimal glands.

Lipid Layer

The Oily Top

Finally, the top “oily” lipid layer of the tear film is made up of lipids or oils produced from the meibomian glands. When MGD is present, our glands do not consistently produce the oil necessary for a stable tear film and the aqueous layer will evaporate.

Eye Diagram

A Leading Cause of Dry Eye Symptoms: Blocked Glands in The Eye Lids

Fortunately, many dry eye patients enjoy healthy tear production that, in some, can be evidenced by a common dry eye symptom, excessive tearing, the eyes response to combat irritation and dryness.  If your tear production is healthy, your eye care professional should check meibomian gland function and structure to determine if the protective tear film oil is being properly produced and spread on the surface of your eye.

While MGD is most often detected in adults over 40, the condition does not discriminate based on age and has also been seen in kids and young adults. That is why checking for MGD should be a part of a regular eye exam. MGD, if caught early, may play a significant role in avoiding chronic dry eye symptoms and to prevent the potential for permanent gland loss.

Normal Gland Structure

Normal Gland Structure

Gland Shortening And Los

Gland Shortening and Loss

Significant Gland Loss

Significant Gland Loss

Severe Gland Loss

Severe Gland Loss

External Dry Eye Causes

Dry eye Syndrome and chronic dry eye symptoms can have significant impact on daily lifestyles and can impede on simple activities such as reading, working on a computer, enjoying the outdoors or watching a TV.

One contributing factor to increased dry eye symptoms can be long-periods of digital screen time that can cause decreased blink rates.  A healthy blink rate is essential to activating the oil-producing Meibomian glands to spread the needed tear oil across the surface of the eye. When blink rates decrease, it impacts long term functionality of the glands.

Other contributing factors that cause dry eye symptoms to flare up are dry climates, smoke, indoor air circulation, and wind.  And for some, dry eye is the result of the aging process.

Medical Related Dry Eye Causes

In addition to environmental factors that contribute to Chronic Dry Eye symptoms, there are various diseases, medications or medical procedures that can cause Dry Eye symptoms. If you are experiencing any of the below medical conditions or receiving any of these treatments, you should discuss with your eye doctor to get to the root cause of your Dry Eye symptoms. The following are common conditions or treatments that can lead to chronic Dry Eye Symptoms:

  • Rheumatoid Arthritis, Sjogren’s syndrome, thyroid disease and lupus
  • Medicines such as beta-blockers, antihistamines, diuretics and anxiety medications
  • Refractive surgery such as LASIK surgery
  • Various prescription and non-prescription medications
  • Swollen, red irritated eye lids, commonly referred to as Blepharitis
  • Out-turning of the eye lids (ectropion) and in-turning of the eye lids (entropion)
  • Contact lens use for long periods of time