Introduction

Did you know that dry eyes are not just a problem for a handful of people? It's a widespread condition that can potentially affect billions of people around the world! That's right, you're not alone in this.

In fact, statistics show that the prevalence of dry eyes ranges from 5% to a whopping 50% of the population. That means anywhere from a small fraction to nearly half of the people you know might be dealing with dry eyes.

So, the next time you're in a crowded room, take a moment to imagine how many people in there could be silently battling with dry eyes. It's a common challenge, but fortunately, there are ways to manage and find relief. You're part of a large community, and together we can tackle dry eyes and keep our eyes happy and comfortable.

Anatomy of Tears

Before we begin to talk about the symptoms of dry eye and treatment, we need to talk about the anatomy.

Let’s start with basics? What are tears made up of?

There are three components of tears.

• Lipid (Oil) Layer:
  • The outermost layer of the tear film is the lipid layer.
  • It is composed of oils produced by the meibomian glands located in the eyelids.
  • The primary function of this layer is to reduce evaporation of tears and provide a smooth surface for the tear film. It helps maintain tear stability and prevents

• Aqueous (Watery) Layer:
  • The middle layer is the aqueous layer, which forms the bulk of the tear film.
  • It is primarily composed of water, electrolytes, and proteins.
  • This is made by the lacrimal gland
  • This layer provides moisture, oxygen, and essential nutrients to the cornea and conjunctiva. It also helps flush away debris, bacteria, and foreign particles.

• Mucin Layer:
  • The innermost layer of the tear film is the mucin layer.
  • It is produced by the goblet cells in the conjunctiva
  • The mucin layer allows tears to spread evenly and adhere to the ocular surface, providing a smooth and stable surface for the other tear layers.

As you can see, the tears are complex, and they ultimately drain into the punctum, which is located into your eyelids. The tear ducts eventually go into your nose.  

Causes of Dry Eyes

There are many causes of dry eyes, but to make it simple, I want you think about dry eyes as 2 main categories. Either you don’t make enough tears or your tears evaporate quickly.

Let’s talk about why you don’t make enough tears

• Age: Tear production tends to decrease with age, making older individuals more prone to dry eyes.
• Hormonal changes: Hormonal fluctuations, such as during menopause in women, can affect tear production.
• Medical conditions: Certain medical conditions, such as Sjögren's syndrome, rheumatoid arthritis, lupus, diabetes, and thyroid disorders, can cause decreased tear production.
• Medications: Certain medications, such as antihistamines can reduce tear production.

Let’s talk about why your tears evaporate: you can even break this down into 2 broad categories. #1 Your tears evaporate quickly because your tears are not stable #2 your tears are likely to evaporate

Tear instability is a big cause

• Tear Film Imbalance: Remember our anatomy - the tear film consists of three layers—lipid (oil) layer, aqueous (watery) layer, and mucin layer. Imbalances in these layers can disrupt tear film stability, leading to dry eyes.
• Insufficient Lipid (oil) Layer:
  • Recall, that the oil layer is made by the meibomian gland. If the glands are not working, you have Meibomian gland dysfunction (MGD). There are many different causes of MGD.
    • Obstruction of the gland openings: from thick secretions, debris, or inflammation
    • Inflammation of the Glands: Inflammatory conditions, such as blepharitis (including Demodex blepharitis) and rosacea, can cause inflammation and damage to the meibomian glands, thus can lead to changes in gland structure, altered meibum production, and gland dysfunction.
    • Hormonal Changes: Hormonal imbalances, particularly during menopause or hormonal fluctuations, can affect the function of the meibomian glands and contribute to MGD.
    • Aging: As individuals age, the meibomian glands may naturally deteriorate, leading to reduced function and MGD.
  • Insufficient mucin layer: Reduced production of the mucin layer, which helps tears spread evenly across the ocular surface, can lead to dry spots on the eyes.

Your Tears are Normal, but there are other factors causing your tears to evaporate more

• Environmental factors: Dry or windy climates, high altitude, air conditioning, and heating systems can contribute to increased tear evaporation.
• Eyelid abnormalities: Structural issues with the eyelids, such as ectropion (outward turning of the eyelid) or entropion (inward turning of the eyelid), can impact tear distribution and stability.
• Eyelids remain open – some people have a partial blink or Extended periods of screen time or reading. Reduced blinking keeps your eyes open more and allows the tears ot evaporate.

Symptoms

• Dryness: The primary symptom of dry eyes is a persistent feeling of dryness in the eyes. It may be described as a scratchy, gritty, or sandy sensation.
• Eye Irritation: Individuals with dry eyes often experience irritation or discomfort in their eyes. This can manifest as a burning or stinging sensation.
• Redness: Dry eyes can cause the blood vessels on the surface of the eye to become more prominent, resulting in redness or bloodshot appearance.
• Excessive Tearing: Dry eyes can cause tearing, which may seem counterintuitive, but it is a common response of the eyes to insufficient lubrication. When the eyes are dry, the lacrimal glands, responsible for producing tears, can be triggered to produce more tears in an attempt to compensate for the dryness. This excessive tearing is known as reflex tearing or "reflex overflow."
  • When the ocular surface is dry, it becomes irritated.
  • The nerves send a message to the lacrimal gland indicating that more tears are needed to lubricate and protect the eyes.
  • As a result, the lacrimal glands produce a sudden increase in tear volume to alleviate the dryness and discomfort.
  • However, the composition of reflex tears differs from the normal tears produced by the lacrimal glands. Reflex tears are typically more watery and lack the necessary components, such as oils and mucins, to effectively lubricate the eyes.
  • Consequently, the excessive tearing may not provide long-lasting relief or address the underlying cause of dry eyes.
• Eye Fatigue: Dry eyes can contribute to eye fatigue or a sensation of tiredness in the eyes, especially after prolonged periods of reading, computer use, or other visually demanding activities.
• Blurred Vision:
  • Irregular Tear Film: The tear film plays a crucial role in maintaining a smooth and clear surface on the cornea, which is essential for clear vision.
  • In dry eyes, the tear film may become unstable or unevenly distributed across the ocular surface. This can result in areas of dryness or inconsistency in the tear film, leading to blurred vision.
  • Tear-Induced Refractive Changes: This is a little advanced now, but surpisingly, the tears is the most critical part at focusing light towards the back of the eye. For the physics majors out there, the air-tear film interface contributes the most to the bending of light.
• Sensitivity to Light: Dry eyes can make the eyes more sensitive to light, causing discomfort or pain when exposed to bright lights or glare. This is known as photophobia.
• Eye Itching: Individuals with dry eyes may experience occasional itching or a sensation of something in the eye, leading to an urge to rub the eyes.

Pathophysiology

Dry eyes can lead to inflammation through various mechanisms. Here's how it happens:

• Epithelial Damage: The cornea and conjunctiva, which make up the ocular surface, can become exposed and vulnerable when the tear film is insufficient.. Insufficient lubrication and moisture can harm the cells lining the surface of the eyes, triggering inflammation.
• Increased Osmolarity: Dry eyes have tears with higher solute concentration. The elevated osmolarity can lead to cellular dehydration and stress on the ocular surface cells. This can activate inflammatory pathways and contribute to ocular inflammation.
• Disrupted Barrier Function: Weakened tear film stability allows irritants and pathogens to penetrate the ocular surface, triggering inflammation.

Together, this causes inflammation and there are inflammatory mediators, such as cytokines, chemokines, and prostaglandins that are released. In dry eyes, these cells can be activated and release inflammatory substances that recruit more immune cells to the site of inflammation. This cascade of inflammatory mediators can perpetuate and amplify the inflammatory response.

The resulting inflammation can cause redness, swelling, pain, and tissue damage on the ocular surface. It can also affect the tear-producing glands and exacerbate the underlying dry eye condition. Effective management of dry eyes aims to reduce inflammation, restore tear film balance, and improve overall ocular health.

Natural Treatments

There are very basic ways to take care of dry eyes. You don’t necessarily need prescription medications to take care of dry eyes. Here are some very basic things you can do. And never forget the anatomy.

• Take Breaks and Do Blinking Exercises.
  • Blinking Exercises: Remind yourself to blink regularly, especially when engaging in activities that require focused visual attention, such as computer work or reading. Blinking helps spread tears across the ocular surface and prevents excessive evaporation.
  • A good rule I use to help remind people is the 20/20/20 rule. Every 20 minutes, look at something 20 feet away for 20 seconds to reduce eye strain. This will also allow you to blink more
• Warm Compresses: Apply a warm compress to your closed eyelids. The warmth can help stimulate the oil glands in the eyelids (meibomian glands) to produce a healthier lipid layer of the tear film, reducing tear evaporation. I specifically recommend microwavable eye masks because these can keep the heat on the eyelids long enough. You need a solid 10 minutes for each application.
• Change Your Environment: Keep Your Tears from Evaporating
  • Humidifier: This one makes sense. If your tears are evaporating, a humidifier will prevent that.
  • Avoid ceiling fans. The movement of air over the ocular surface can cause the tears to dry up faster.
  • It is actually why some companies produce dry eye goggles.
  • Keep Good Hygiene – Remember, the bacteria and other organisms can cause irritation of the eyelids which can cause MGD!
• Omega-3 Fatty Acids: Include foods rich in omega-3 fatty acids in your diet or consider taking omega-3 supplements.
  • Omega-3s play an important role in the oil of the tear film.
  • Omega-3s have also been shown to play a role in suppressing some of the pro-inflammatory pathway.

Medications, Eye Drops, Oral Medications

Unfortunately, if you have made it this far in the lecture, odds are that you have more advanced dry eyes where additional therapies are needed.

Fortunately, there is a lot of effective treatment options out there. As always, let’s start with the basics.

Replace Your Tears

• Artificial Tears are a simple, cost-effective way to replace the aqueous part of your tears and is a landmark part of dry eye management. There are a variety types of eye drops out there but I specifically recommend preservative-free artificial tears. Note – Visine is not an artificial tear and can actually make dry eyes much worse.
• In fact, there are so many different types of artificial tears now. Most are still eye drops, but you can even use eye sprays if you find eye drops hard to use and even gels which can last for hours!

Reduce Inflammation – Remember the inflammatory pathway we mentioned earlier, this can contribute to dry eyes and irritation so we need to break this cycle.

• Prescription Eye Drops:
  • Steroid Eye Drop are often used. Steroids help reduce inflammation rapidly and provide temporary relief. However, long-term use of steroids can have side effects like cataracts and glaucoma, so they are typically used for short durations under close supervision.
  • Cyclosporine (Restasis, Cequa): Cyclosporine is an immunosuppressant that helps reduce inflammation on the ocular surface by inhibiting certain immune cells.
  • Lifitegrast (Xiidra): Lifitegrast inhibits the activity of a protein called lymphocyte function-associated antigen-1 (LFA-1), which is involved in the inflammatory response. By blocking LFA-1, Lifitegrast helps to reduce the infiltration of inflammatory cells into the ocular surface and prevent the release of inflammatory mediators.
  • Oral Medications: In some cases, oral medications may be prescribed to manage underlying conditions contributing to dry eyes. One of my favorites is doxycycline.
• Anti-Inflammatory Effects: It reduces inflammation on the ocular surface, alleviating symptoms like redness and irritation.
• Improved Meibomian Gland Function: Doxycycline has been found to improve meibomian gland function by decreasing inflammation, reducing bacterial overgrowth, and normalizing the composition of the meibum (the oil secreted by the glands).
• Bacterial Control: It helps control bacterial growth on the eyes and within meibomian glands, promoting overall eye health.

Increased Tear Production – In fact, there is a new medication that is out that has been shown to incrase tear production.

• Tyrvaya is a highly selective cholinergic agonist that binds to cholinergic receptors with high affinity.
• It is a nasal spray and it activates the trigeminal parasympathetic nerve. The trigeminal parasympathetic pathway innervates lacrimal glands thus increasing tear production
• Although the exact mechanism is still unknown, the analogy I like using is eating spicy foods like wasabi. When you eat something spicy or it gets up in your nose, what do you do? You cry.

Procedures

There are also a variety of procedures to help with dry eyes as well.

The easiest one is punctal plugs. Punctal plugs are small devices inserted into the tear ducts (puncta) of the eyes to block the drainage of tears. So essentially, you are trapping your teras.

Another approach is to address the oil layer of the tears. Remember, a common cause of dry eyes is MGD. patients with MGD have clogged oil glands. There are a variety of products that help relieve the clogged oil glands, but they all work in a similar fashion.

• LipiFlow and TearCare utilizes devices that applies localized heat to the eyelids. This liquefies hardened oils within the glands. This helps facilitate the release of obstructed oils. That makes sense right? Heat melts butter. If your oil in the oil glands are solid like butter, they are not coming out of the glands.
• Next, to assist with the expression of the melted oil glands, the Lipiflow device provides gentle pressure. With the TearCare, your doctor will help express the oil glands.

Take Away

Dry eyes can have various causes, and treating them requires addressing the specific underlying factors. Here's an interesting point to remember: Dry eye therapy is not an overnight miracle. Just like it took time for your dry eyes to develop, it will take time to improve them. So, don't expect a quick fix!

Consistency is crucial in managing dry eyes. Think about dry skin. Would you expect applying lotion once to magically solve the problem? Of course not! You need to moisturize daily. Similarly, you need to be dedicated to your dry eye treatment regimen and follow it consistently to see long-term improvements.

So, don't lose hope if you don't see immediate results. Stick to your dry eye treatment plan, be patient, and remember that with time and consistent care, relief from dry eyes is within reach.