What Do Artificial Tears Contain
Natural tears act as a protective barrier between the eyes and the surrounding environment. They lubricate the ocular surface, wash away small particles, support clear vision, and help protect the cornea and conjunctiva from irritation and infection.
The tear film consists mainly of an aqueous-mucin layer covered by an outer lipid layer. The aqueous component provides moisture and essential substances, while the lipid layer creates a smooth optical surface and slows tear evaporation.
When the eyes do not produce enough tears, or when tears evaporate too quickly, artificial tears can supplement the natural tear film. Depending on their ingredients, they may do more than simply provide moisture: they can improve tear stability, protect ocular surface cells, reduce evaporation, and support healing.
Six Main Components of Artificial Tears
1. Viscosity-Enhancing Agents
Viscosity-enhancing agents are among the most common ingredients in artificial tears. They increase the thickness of the solution, allowing it to remain on the eye for longer.
Their main functions include:
๐ Lubricating the surface of the eye
๐ Reducing friction between the eyelid and the cornea
๐ Relieving burning, dryness, and irritation
๐ Improving tear-film stability
๐ Helping retain moisture on the ocular surface
Common viscosity-enhancing ingredients include:
๐ Cellulose derivatives
๐ Dextran
๐ Gelatin
๐ Liquid polyols
๐ Polyvinyl alcohol
๐ Povidone
One frequently used ingredient is sodium carboxymethylcellulose, or CMC. It holds water and adheres to the ocular surface, making it useful for mild to moderate dry-eye symptoms.
More viscous products may remain effective for longer but can temporarily blur vision. Gels and ointments are therefore often more suitable for night-time use.
2. Electrolytes
Natural tears contain electrolytes such as:
๐ Sodium
๐ Potassium
๐ Chloride
๐ Magnesium
๐ Calcium
These substances help maintain normal hydration, pH, osmotic balance, and cellular function on the ocular surface.
Electrolytes in artificial tears may help make the formulation more similar to natural tears and support the health of corneal and conjunctival cells.
Some formulations contain buffering agents such as boric acid to help maintain an appropriate pH. Certain electrolyte-based systems may also form part of a preservative system, such as SofZia.
3. Osmoprotectants
In dry-eye disease, excessive tear evaporation may make the tear film unusually concentrated. This condition is known as tear hyperosmolarity.
Hyperosmolar tears can stress and damage cells on the cornea and conjunctiva, contribute to inflammation, and promote programmed cell death, or apoptosis.
Osmoprotectants help ocular surface cells retain water and tolerate changes in tear concentration.
Examples include:
๐ L-carnitine
๐ Erythritol
๐ Betaine
๐ Sorbitol
๐ Glycerine
๐ Trehalose
Trehalose is a naturally occurring sugar found in plants, fungi, microorganisms, and some animals. It can help protect cells against dehydration and environmental stress.
Artificial tears containing osmoprotectants may be particularly useful when dry eye is associated with increased tear concentration and ocular surface damage.
4. Oils and Surfactants
Evaporative dry eye is commonly associated with an inadequate or unstable lipid layer.
This may occur when the meibomian glands along the eyelid margins do not produce enough healthy oil. Without an effective lipid layer, the aqueous component of tears evaporates more quickly.
Oil-containing artificial tears are designed to support or replace part of this lipid layer. They may contain:
๐ Liposomes
๐ Fine oil nanodroplets
๐ Oil-in-water emulsions
๐ Mineral or other medically formulated oils
๐ Surfactants that help distribute oil evenly
These formulations may help:
๐ Reduce tear evaporation
๐ Improve tear-film stability
๐ Smooth the ocular surface
๐ Relieve burning and irritation associated with evaporative dry eye
๐ Support patients with meibomian gland dysfunction
Some artificial tears also contain antioxidants or vitamin-related ingredients, such as:
๐ Vitamin A
๐ Vitamin E
๐ Coenzyme Q10
๐ Lipoic acid
๐ Vitamins B5, B6, or B12
๐ Epsilon-aminocaproic acid
However, evidence for individual antioxidant ingredients remains limited because many have been studied only as part of combined formulations. Further research is required to determine their specific clinical benefits.
5. Ingredients That Support Healing and Reduce Inflammation
Certain artificial-tear ingredients may support the repair of the ocular surface as well as provide lubrication.
Hyaluronic Acid
Hyaluronic acid, or HA, is a naturally occurring substance with strong water-binding properties.
It may help:
๐ Retain moisture
๐ Improve lubrication
๐ Stabilise the tear film
๐ Promote migration and healing of surface cells
๐ Reduce friction during blinking
High-molecular-weight hyaluronic acid may also have soothing and anti-inflammatory properties.
Some studies suggest that HA may support healing after corneal abrasions or certain chemical injuries. However, serious eye injuries require specialist treatment and should not be managed with artificial tears alone.
Carboxymethylcellulose
CMC can attach to corneal epithelial cells and remain on the ocular surface for an extended period. It may support recovery of minor surface damage and improve tear retention.
Cationic Emulsions
Cationic emulsions carry a positive electrical charge that helps them adhere to the negatively charged surface of the eye.
They can:
๐ Support the lipid layer
๐ Improve the distribution of oils across the tear film
๐ Reduce evaporation
๐ Remain on the eye for longer
๐ Support the healing of minor epithelial damage
Artificial tears may reduce irritation and support the ocular surface, but they are not a substitute for prescription anti-inflammatory treatment when significant inflammation is present.
6. Preservatives
Multi-dose bottles generally contain preservatives to prevent microbial contamination after opening and to extend the product’s usable life.
Benzalkonium Chloride
Benzalkonium chloride, or BAK, is a widely used preservative. It is effective against microorganisms but may irritate or damage the ocular surface when used frequently or over a long period, particularly in people with moderate or severe dry eye.
Softer Preservative Systems
Newer preservatives are designed to cause less irritation. Examples include:
๐ Polyquaternium-1, or POLYQUAD®
๐ Sodium chlorite systems such as PURITE® or OcuPURE®
๐ Edetate disodium, or EDTA
Some preservatives break down into less irritating components after exposure to light or the tear film.
Preservative-Free Artificial Tears
Preservative-free artificial tears are commonly recommended for people who:
๐ Need eye drops more than four to six times per day
๐ Have moderate or severe dry eye
๐ Wear contact lenses
๐ Have sensitive eyes
๐ Have ocular surface disease
๐ Have recently undergone eye surgery
๐ React to preserved eye drops
Preservative-free products are available in single-use containers and in specially designed multi-dose bottles that prevent contamination.
Different Artificial Tears Serve Different Purposes
Artificial tears are not identical. Their suitability depends on the underlying type of dry eye.
Aqueous-Deficient Dry Eye
When the eyes do not produce enough tears, products containing water-binding and viscosity-enhancing agents may be helpful.
Common ingredients include:
๐ Hyaluronic acid
๐ Carboxymethylcellulose
๐ Hydroxypropyl methylcellulose
๐ Povidone
Evaporative Dry Eye
When tears evaporate too quickly because of an inadequate lipid layer, oil-containing emulsions or liposomal products may be more appropriate.
Treatment may also include warm compresses and eyelid hygiene when meibomian gland dysfunction is present.
Severe or Persistent Dry Eye
Patients with more severe disease may need additional treatment, such as:
๐ Prescription anti-inflammatory eye drops
๐ Treatment for eyelid or meibomian gland disease
๐ Punctal plugs
๐ Autologous serum eye drops
๐ Moisture-retaining eyewear
๐ Treatment of an underlying autoimmune or systemic condition
How to Use Artificial Tears Safely
๐ Wash your hands before applying the drops.
๐ Avoid touching the bottle tip to the eye, eyelid, or eyelashes.
๐ Use the recommended number of drops.
๐ Close the eye gently after application rather than blinking forcefully.
๐ Follow the storage instructions on the packaging.
๐ Discard single-use containers after opening unless the product instructions state otherwise.
๐ Remove contact lenses when required by the product instructions.
๐ Do not share eye drops with another person.
When to Consult an Ophthalmologist
Medical assessment is recommended when dry-eye symptoms:
๐ Persist despite using artificial tears
๐ Require very frequent application
๐ Are accompanied by significant redness or pain
๐ Cause sensitivity to light
๐ Affect vision
๐ Occur after an eye injury or chemical exposure
๐ Are associated with discharge or suspected infection
๐ Develop after eye surgery
An ophthalmologist can evaluate tear production, evaporation, eyelid function, meibomian glands, corneal health, and tear-film stability.
Artificial tears contain more than water. Their ingredients may replace missing tear components, reduce evaporation, stabilise the tear film, protect ocular surface cells, and support healing. Selecting the appropriate formulation according to the cause and severity of dry eye is therefore essential for achieving effective and lasting relief.
Reference :
Independent Writer
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