Tears are not just for crying. Your eyes constantly produce tears to help lubricate and protect your corneas. Each time you blink, the tears are spread out across the eye, coating it. For people who suffer from dry eye syndrome, the eyes simply do not produce enough tears consistently to do the job or those tears evaporate too quickly.

According to the DEWS II (The Tear Film and Ocular Surface Society’s Dry Eye Workshop in 2017) definition of dry eye, inflammation is one of the key reasons for dry eye.

“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.”

Let us break down this definition a little bit to make it more palatable.  “Dry eye is a multifactorial disease” means that there is not one thing that is causing your dry eye. It is a combination of a lot of things that may be causing it to occur.  

The problems that are occurring lead to “loss of homeostasis of the tear film,” meaning that the tear film is no longer functioning like it was designed to.  “Accompanied by ocular symptoms” means that you may notice the typical dry eye symptoms we will list below.

“Hyperosmolarity” means that the tears actually contain a high salt content, which is a sign that there is “ocular surface inflammation and damage.”  Damage to the ocular surface means inflammation, or irritation, on the front surface of the eye.  

“Neurosensory abnormalities” means that the nerves of the eye are damaged, and you may not have as much “feeling” in the eyes as you used to, or nerve innervation is not what it used to be. On the other hand, your eyes may become even more sensitive.

Dry eye is one of the most common eye afflictions. It is most prevalent in older women but can affect people of any gender at any age. Around 3.2 million women and 1.68 million men aged 50 and over suffer from dry eye disease.

HOW THE TEARS WORK

The tear film that coats the front of the eye is overly complex and contains three important layers. The outer layer of the tear film is oily, produced by special glands (meibomian glands) within the eyelid, and this serves to prevent evaporation of the saltwater middle layer.  Meibomian gland dysfunction occurs when these oil glands are not producing oil or the oil is too thick to release, therefore causing dry eye disease. 

The saltwater middle layer comes from the lacrimal gland, which is in the upper, lateral part of your eyelid.  Sjogren's is the most common cause of a problem with this layer of the tears. 

The inner layer is made of mucus or mucin secreted from cells onto the front surface of the eye and is important in helping the saltwater layer spread evenly across the front of the eye. The mucin layer is secreted by goblet cells located in your conjunctiva (next to your cornea).

As discussed, glands located in and around your eyelids make tears. Healthy tears consist of these three parts — oil, water, and mucus. Each part plays a vital role in the overall health of the eye. The water adds moisture. The oil protects the water from evaporation. The mucus helps the tears spread evenly and coat the surface of the eye.

Tears рlау a key role in promoting сlеаr vіѕіоn, warding off infection, and keeping the front ѕurfасе оf thе еуе сlеаn, moist, and comfortable. When a person no longer produces enough tears or their tears do not have the right balance of the three ingredients, dry eye disease is the result.

WHY IS BLINKING IMPORTANT?

Blinking is super important for your eyes because it spreads the tears across the front of the eye while also causing excess tears to be pushed out of a drainage system that leads from the inner corner of the eyelids into the nose.

This drainage system starts at the puncta, which are two small holes in the upper and lower eyelids by the nose, runs through the nasolacrimal duct, and then drains into your nose. Therefore, your nose starts to run when your eyes are watering.  

When you stare at digital devices all day, such as your computer screen, tablet, or phone, you naturally blink much less. In fact, studies have shown that you blink almost 60% less while using a computer or reading versus what you normally would. This means blinking only about 4-5 times per minute, which is not much at all when you consider that the normal blink rate is around 10 blinks per minute.

This lack of blinking not only leads to an increase in the evaporation of your tears, but it can, over time, increase inflammation which further contributes to dry eyes.

CAN DRY EYE SYNDROME CAUSE BLURRY VISION?

In short, yes – blurry vision is a common symptom of dry eye syndrome. In addition to keeping the cornea healthy and lubricated, tears are an important part of our ability to see. To have clear vision, your tears must have the correct balance of water, oils, and mucus that enables the tear film to spread across the cornea. If your tear quality is compromised, your tears may evaporate too easily, become too oily, or be filled with mucus. Any of these issues will prevent the tears from spreading over the cornea and will hinder your ability to see clearly. It will likely also cause irritation and discomfort in your eyes.

To temporarily help increase your vision that has been affected by poor tear quality, you can try blinking fully and frequently. Blinking will re-spread the tear film across the cornea. However, if the problem persists, do not hesitate to consult a doctor to evaluate whether you have dry eye syndrome and to determine what the best treatment is to restore clear vision.

SYMPTOMS OF DRY EYE DISEASE

People who experience dry eye disease often report feeling irritated, itchy, gritty, or burning eyes; a feeling of debris in their eyes; excess watering; red eyes or pain in the eye. Other symptoms include:

• Burning sensation
• Itchy eyes
• Heavy eyes
• Aching sensations
• Fatigued eyes
• Sore eyes
• Red eyes
• Dryness sensation
• Photophobia, or light sensitivity
• Blurred vision

Although counter-intuitive, watery eyes can be a symptom of dry eye syndrome. This is because the dryness on the cornea may over-stimulate the production of the watery component of your tears to protect the eye. This is known as “reflex tearing” and the tears unfortunately do not stay on your eye long enough to correct dry eye syndrome. Dry eye syndrome can also impact the outcomes of cataract and LASIK surgery, and these surgeries both have a big effect on dry eye.