How Lubricating Eye Drops Work on Different Layers of the Eye

• The surface of the eye is a delicate and intricate structure that needs a well-balanced tear film to maintain comfort, clarity, and overall ocular health. Dry eye syndrome, which affects millions of people worldwide, occurs when the eye does not produce enough tears or when the quality of the tears is compromised. This results in discomfort, irritation, and potentially more serious complications if left untreated.
• To combat dry eye symptoms, our range of lubricating eye drops is very carefully formulated with specific ingredients that are directed at different layers of the tear film and the corneal surface. Understanding how these ingredients work can help you choose the right product to suit your unique needs.

The Anatomy of the Tear Film
It has three distinct layers, each performing its specific role in eye health:

The Lipid (Oily) Layer is the outermost layer of the tear film. It protects the aqueous layer below it from evaporation, as well as from the environmental impact, and thus aids in maintaining the integrity of the tear film over time.
The aqueous layer forms the central portion, which constitutes most of the tear film. This layer hydrates the cornea, bringing it necessary nutrients and protective antibodies. The aqueous layer also plays a part in flushing out foreign particles and maintaining a smooth eye surface.
Mucin Layer: The innermost layer, closest to the corneal surface. It consists of glycoproteins that help the aqueous layer adhere uniformly to the eye’s surface, creating a smooth refractive interface for light to pass through. The mucin layer also plays a key role in stabilizing the tear film.
All of these layers are critical to a healthy ocular surface. Any interruption to these layers results in symptoms associated with dry eye and makes necessary the use of eye drops capable of balancing these layers appropriately.

Key Ingredients and Mechanisms

1) Hydroxypropyl Guar (HP Guar):

– Action: HP Guar is a very effective gelling agent that transforms into a protective, gel-like matrix once it comes into contact with the eye’s natural tear film. This matrix mimics the mucin layer and adheres to the eye’s surface, helping to stabilize and maintain the tear film for extended periods. Also, HP Guar retains moisture and creates a cushioning effect, particularly suitable for moderate to severely symptomatic dry eye patients, due to its ability to fortify both the mucin and aqueous layers, resulting in long-lasting relief against dryness and irritation.

– Target Layers: Mucin Layer and Aqueous Layer

– Ideal For: Patients with a poor mucin layer or those in need of long-term hydration and stabilization of the tear film.

2) Mineral Oils
Action: Mineral oils are an emollient reinforcing the lipid layer of the tear film. By creating a retardant barrier to slowing evaporative loss, mineral oils are helpful in keeping more moisture on the surface of an eye. This is more important for patients who might suffer from evaporative dry eyes caused by a malfunction in their lipid layer, which can enhance evaporative loss and destabilize the tear film. Mineral oils in eye drops help protect the ocular surface from drying out, thus preventing the cascade of discomfort associated with dry eyes.

– Target Layer: Lipid Layer

– Ideal For: Patients with evaporative dry eye or those with rapid tear film breakup due to a deficient lipid layer.

Carboxymethylcellulose (CMC) and Hydroxypropyl Methylcellulose (HPMC):
– Action: CMC and HPMC are cellulose-derived polymers that provide viscosity to the tear film, thus improving the aqueous layer. These ingredients mimic the natural thickness of tears, offering lubrication and moisture that soothes the eye and protects the corneal surface. CMC and HPMC work by binding to the eye’s surface, forming a protective barrier that prevents moisture loss and shields against irritants. This makes them particularly effective in providing relief from mild to moderate dry eye symptoms and improving overall comfort.

– Target Layer: Aqueous Layer

– Ideal For: Individuals who need enhanced tear thickness and prolonged hydration without altering the lipid layer.

3) Sodium Hyaluronate:

– Action: Sodium hyaluronate is a naturally occurring biopolymer with exceptional water-retaining properties. Sodium hyaluronate is renowned for its ability to attract and hold large amounts of water, thus delivering intense hydration to the eye’s surface. With high molecular weight, it can build a viscoelastic protective layer over the cornea, which not only acts as a lubricant but also promotes healing of the ocular surface. This ingredient is beneficial especially for people who have the severe dry eye, in which prolonged retention of moisture and stability of tear film are important.

– Target Layer: Aqueous Layer

– Best Suited For: People who experience acute dry eye, especially during the day and especially after the irritation or discomfort happen often.

4) Polyethylene Glycol 400 (PEG 400) and Propylene Glycol (PG):
– Action: PEG 400 and PG are humectants that work synergistically to draw moisture to the surface of the eye, thus improving the quality and consistency of the tear film. PEG 400 has a high affinity for water, while PG acts as a conditioning agent, ensuring that the moisture remains on the ocular surface for extended periods. Together, these ingredients provide a balanced approach to hydrating the aqueous and lipid layers, making them effective for a broad spectrum of dry eye conditions. PEG 400 and PG maintain the integrity of both layers, thus reducing the sensation of dryness and preventing further irritation.

– Target Layers: Aqueous Layer and Lipid Layer

– Suitable For: Those individuals with the requirement of having tear film that is well balanced in its hydration levels, particularly for mild to moderate levels of dry eye complaints.

6) Trehalose:
– Effect: Trehalose is one type of disaccharide sugar that boasts powerful protective and stabilizing activities. This acts as an antioxidant protecting eye cells from harmful effects resulting from environmental stressors, such as ultraviolet light and oxidative damage. Trehalose also uniquely protects and stabilizes cell membranes, and it’s very effective at preserving the integrity of the ocular surface. Trehalose in eye drops maintains the viability of cells and aids in the natural healing of the cornea. Formulations containing trehalose are especially beneficial for patients with chronic or severe dry eye, where cellular protection and recovery are key.

– Target Layers: Aqueous Layer and Corneal Surface

– Best Suited For: Patients who have severe or chronic dry eyes, exposed to extreme environmental stress, or suffering from oxidative stress.

Choosing the Proper Eye Drop for Your Prescription
The complexity of the tear film and the multiple causes of dry eye necessitate a careful choice of eye drops that will target the affected layer or layers in your case. Whether you are suffering from tear deficiency, evaporative tear loss, or damage to the corneal surface, our line of lubricating eye drops is designed to target relief where it is most needed.

– For long-term stabilization and hydration: Use products that contain Hydroxypropyl Guar.

– For locking in moisture and protecting the eyes: Seek out drops with Sodium Hyaluronate.

– For the inhibition of rapid tear evaporation: Use formulations with Mineral Oils.

– For balanced hydration across the tear film: Use eye drops that contain Polyethylene Glycol 400 and Propylene Glycol.

– For cellular protection and repair: Seek out products that contain Trehalose.

Therefore, by understanding how each ingredient works for your eyes and what your eyes require, you can make an informed choice that brings them your optimum comfort, hydration, and protection.