Tears and their relationship with dry eye

17/06/2024

Tears are an essential component of eye health. The average person produces between 0.2 to 0.5 millilitres of tears per day. There are several types of tears, and they serve several important functions, such as lubricating the eyes, protecting against infection, and removing foreign particles.

Basal tears lubricate and nourish the cornea and conjunctiva, providing a constant protective barrier. They are composed of a mixture of water, lipids (fats), mucins, proteins, and electrolytes. For their part, reflex tears are produced in response to eye irritations, such as smoke, wind or foreign bodies. Their composition is similar to that of basal tears, but they are produced in greater volume.

Finally, there are also emotional tears. These tears are produced in response to strong emotions and contain additional hormones and proteins not found in other types of tears, such as prolactin, adrenocorticotropic hormone, and leucine enkephalin. Interestingly, humans are the only creatures that produce emotional tears, a phenomenon believed to be linked to the evolution of communication and social relationships.

Tears and dry eye

Understanding the function and different types of tears is essential for recognizing their importance in eye health and to effectively address conditions such as dry eye. Dry eye occurs when tears cannot provide adequate lubrication for the eyes due to various reasons.

• Decreased tear production: caused by factors such as age, certain medications (antihistamines, antidepressants, etc.), medical conditions (Sjögren's syndrome, diabetes), or damage to the tear glands.
• Excessive evaporation of tears: this may be due to exposure to wind, dry air or an inadequate lipid layer in tears, which is responsible for slowing evaporation.
• Imbalance in tear composition: if there is an imbalance in the components of tears (water, lipids, mucins), they cannot perform their function properly.

Dry eye treatment

The treatment of dry eye will depend on its underlying cause and the conditions of each patient. Generally, we offer the following treatments:

• Artificial tears: eye drops that help lubricate the eyes. They are preferably without preservatives and available in eye drops, gel or ointment forms.
• Protective glasses: these are used to completely cover the eyes, including the sides, to prevent the evaporation of tears on the ocular surface.
• Medications: anti-inflammatory eye drops that stimulate tear production or reduce inflammation on the ocular surface caused by its dryness. The use of this type of drug must be strictly controlled by an ophthalmologist due to side effects such as increased intraocular pressure.
• Medical procedures: in severe cases, tear plugs can be used to help block the tear ducts and conserve natural tears.
• Regulated intense pulsed light (IPL) therapy: helps stimulate the function of the meibomian glands, thus increasing the lipid layer to reduce tear film evaporation.

Other actions that can help improve the condition of patients are improving the environmental state, increasing humidity with a humidifier or raising awareness of the importance of blinking for the lubrication of the surface of the eye, which should be at least 12- 15 times per minute. At the same time, increasing the intake of omega-3 in the daily diet also helps to improve tear composition.

Dr. Víctor Charoenrook, ophthalmologist at the Barraquer Ophthalmology Centre