DRY EYE and its role in concussions

The tear film (or simply known as “tears”) are composed of three layers: mucus, water, and oil (see figure 1).

The mucus layer is a thin layer closest to the surface of our eye. It is produced by cells on the eye, and functions to adhere and helps spread tears evenly over the ocular surface.

The next layer is the water layer. This layer is produced by the lacrimal gland located just behind the outer parts of our upper eyelid (see figure 2). These tears are spread across the surface of our eye with each blink, and then drained through ducts located in the inner corners of our eyelids and into the back of our nose (fun fact: this is why our nose gets runny when we cry!) (see figure 2). The water layer functions to lubricate the eye, reduce risk of eye infection, wash away foreign matter in the eye, and help with clarity of vision by keeping the ocular surface smooth and clear.

The outermost layer is the oil layer. This layer is produced from glands in our upper and lower eyelids and serves to seal the tear film, preventing evaporation of our tears.

Altogether, the tear film helps to maintain the health of our eye while assisting with clear, comfortable vision.

Dry eye occurs when the production of tears and drainage of tears is not balanced. Either, we are not producing enough tears, the tears are being drained too quickly, or they are being evaporated too quickly. In some cases, it is the quality of tears that is not adequate enough to nourish and lubricate the eye.

1. Age: Dry eye is part of the natural aging process.
2. Gender: Women are more likely to experience dry eye. This is due to hormonal changes that can occur, such as during pregnancy or menopause, or with the use of oral contraceptives.
3. Medications: Certain medications can cause dry eye as a side effect. This includes antihistamines, decongestants, blood pressure medications, acne medication, hormone replacement therapy, and antidepressants.
4. Medical conditions: Certain medical conditions are more likely to have dry eye. This includes rheumatoid arthritis, diabetes, thyroid-associated diseases, Sjogren’s syndrome, and collagen vascular diseases.
5. Environmental conditions: Tears are more likely to evaporate in windy or dry climates, with reduced blinking rate (which tends to occur when we are extremely concentrated like when we are reading, driving, or using a computer), or if the position of our eyelid doesn’t sit well against our eye.
6. Other factors: Dry eye can occur with use of contact lenses and after refractive surgery, such as LASIK.

Symptoms of dry eye include:

• Gritty, scratchy, or burning eyes
• Sensation of having something inside your eye
• Eye pain or irritation
• Eye fatigue
• Excess tearing
• Blurry vision which can improve briefly with blinking
• Light sensitivity
• Difficulty with night driving

Dry eye in concussion patients can be multifactorial. For instance, patients with concussions may have pre-existing medical conditions or may be using medications that are associated with dry eye, such as those listed above. Furthermore, certain medications may be used off-label for concussion management that may induce dry eye. A common example is amitriptyline which can be used for headache and sleep management. In many cases (and given its high prevalence in the general population), dry eye may be present prior to the concussion with the symptoms simply exacerbated after the injury.

As a direct result of the concussion, a person may experience reduced blinking rate and/or inability of the eyes to close completely (a condition called lagophthalmos). Both of these result in a surface that is exposed to the environment and increased risk of evaporation of our tears. This can lead to dry eye and affect the quality of our 20/20 vision (or visual acuity). In more severe cases, tear production from the lacrimal gland can also be affected, resulting in a reduced volume of tears on the ocular surface.

Treatment for dry eye is aimed to restore and/or maintain the tear film in order to minimize dryness and related discomfort. Treatment options may include:

1. Blinking exercises: Yes, these are a thing. Blinking exercises can be used to strengthen eyelid muscles and make our blinks more efficient. This also helps in releasing oils from our eyelids.
2. Increasing humidity: A dry environment can result in increased tear evaporation. Increasing moisture in the air can help our tears evaporate more slowly.
3. Drinking plenty of water: Even mild dehydration can result in dry eye symptoms.
4. Artificial tears: In mild cases of dry eye, adding tears from over-the-counter solutions can be used to supplement natural tear production. I often recommend preservative-free artificial tears because they contain fewer additives, and therefore reduce further irritation of the eyes.
5. Punctal Plugs: The tear ducts can be blocked using tiny plugs (which can be removed if needed) to help keep natural tears in the eyes longer.
6. Prescription eye drops: Prescription eye drops (such as Restasis and Xiidra) are available which reduce inflammation associated with dry eye and helps increase production of natural tears, however these are intended for long-term use.
7. Steroid eye drops: In some cases, a steroid prescription may be prescribed short-term to reduce inflammation that is associated with dry eyes.
8. Meibomian gland expression: In cases of clogged oil glands (called Meibomian glands), your eye doctor may squeeze your eyelids to remove the clogging substance from the glands and improve their function.
9. Warm compresses: Heat can be applied to closed eyelids as another method to open clogged Meibomian glands. My preferred method is using an eye mask which can be heated.
10. LipiFlow: This is an automated, in-office eye treatment which combines the best features of warm compresses and Meibomian gland expression. It uses a device which fits into the eye and eyelids and applies precisely controlled heat to the eyelids to open the glands while applying pulsed pressure to the eyelids to express the clogged glands.
11. Nutritional supplements: Studies have found that supplements, like omega-3 fatty acids, can reduce dry eye symptoms. Good sources of omega-3s include cold-water fish (salmon, sardines, herring, and cod) or flaxseed oil.