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Dry eye disease is often managed with frequent use of artificial tears. However, for many people, symptoms such as dryness, burning, stinging and visual fluctuation persist—or even worsen—over time. One commonly overlooked factor behind this cycle is long-term exposure to preservatives in conventional eye drops, particularly benzalkonium chloride (BAK).

This article explores how preservatives affect the tear film, why they may aggravate dry eye in susceptible individuals, and how preservative-free or low-burden hydration approaches are increasingly favored for long-term eye comfort.

Why Preservatives Can Worsen Dry Eye Over Time

Most multidose eye drops rely on preservatives to maintain sterility after opening. Benzalkonium chloride (BAK) is one of the most widely used agents for this purpose.

While effective as an antimicrobial, repeated exposure of the ocular surface to BAK has been shown to produce dose-dependent toxic effects on corneal and conjunctival epithelial cells. Laboratory and clinical studies have linked chronic BAK exposure to:

● Reduced epithelial cell viability

● Increased inflammatory mediator release

● Shortened tear break-up time (TBUT)

● Compromised tear film stability

Over time, these microscopic changes can translate into very noticeable daily symptoms, including dryness, burning, foreign-body sensation, redness, itching and fluctuating or blurred vision. For individuals already prone to dry eye, frequent use of preservative-containing drops may contribute to a self-reinforcing cycle in which increasing lubrication leads to less tear film stability, not more.

How BAK Disrupts the Tear Film’s Protective Structure

The tear film is composed of three interdependent layers: lipid, aqueous and mucin. Stability depends on the integrity of all three.

Lipid Layer Disruption

BAK has surfactant-like properties similar to makeup removers or detergents. When applied repeatedly to the ocular surface, it can disrupt the lipid layer, reducing its ability to slow evaporation. As a result:

● Tear film evaporation accelerates

● TBUT shortens

● Dryness, burning and light sensitivity become more pronounced

Goblet Cell and Mucin Layer Damage

Beyond the lipid layer, BAK has also been shown to damage conjunctival goblet cells, which are responsible for secreting mucins. When mucin production declines:

● Tear film adhesion to the ocular surface weakens

● Tear distribution becomes uneven

● Symptoms persist despite frequent lubrication

This mechanism helps explain why long-term users of BAK-preserved eye drops—including some glaucoma medications—often experience dry-eye-like symptoms and ocular surface changes over time.

Why Preservative-Free Approaches Are Gaining Clinical Support

As awareness of preservative-related ocular surface stress has grown, clinical reviews and expert recommendations increasingly emphasize reducing lifetime exposure to BAK, particularly in patients who require frequent or long-term topical therapy.

Key points highlighted across reviews and guidelines include:

● Preservative-free formulations or milder preservation systems are preferred when long-term or high-frequency use is expected

● Reducing preservative exposure may improve comfort, tear film stability and overall ocular surface health

● Lower peak concentrations and longer-lasting lubrication can help minimize cumulative irritation

Sustained-Release Lubrication as a Clinical Example

Hydroxypropyl cellulose ophthalmic inserts (Lacrisert) provide a well-documented clinical example of how preservative-free, sustained-release lubrication can benefit moderate to severe dry eye. These inserts gradually release lubricating components throughout the day, helping maintain a more stable tear film environment.

Clinical studies have shown that after approximately four weeks of use, patients experience:

● Significant improvement in dry eye symptom scores

● Reduced corneal and conjunctival staining

● Mean Ocular Surface Disease Index (OSDI) improvements of around 20–21%

● Better tolerance during reading, screen use and night driving

While this is a prescription-based therapy, it illustrates a broader principle: minimizing preservatives while extending hydration duration can meaningfully improve comfort in chronic dry eye management.

Rethinking Daily Eye Hydration for Real-World Use

For many people, dry eye discomfort is not limited to clinical settings. Common daily triggers include:

● Prolonged digital screen use

● Air-conditioned or low-humidity environments

● Long-term contact lens wear

● Makeup use and frequent eye rubbing

In these scenarios, users often reach for hydration multiple times a day—making cumulative preservative exposure an important consideration.

Acewink Open-Eye Mist: A Low-Burden Hydration Approach

Acewink’s open-eye mist was designed with long-term, real-world use in mind, applying insights from preservative-reduction strategies without positioning itself as a medical treatment.

Open-Eye Mist Format

Unlike traditional drops that deliver a single large volume directly into the conjunctival sac, the open-eye mist format delivers an ultra-fine spray that can be evenly distributed across the ocular surface and periocular area with the eyes open. This approach may help reduce localized high-concentration exposure compared with conventional instillation methods.

Designed for High-Frequency Daily Scenarios

The mist is intended for situations where users feel the need to re-hydrate their eyes repeatedly, such as:

● Extended screen time

● Dry indoor environments

● Contact lens wear

● Use alongside eye makeup

The goal is simple: when hydration is needed, users should not have to worry that each application adds another unnecessary preservative burden.

Preservation Strategy and Safety Evaluation

Acewink follows a preservative-free formula or gentle preservation system approach, aiming to balance microbiological safety with reduced long-term ocular surface stress.

Both versions—Refreshing Cool and Gentle Moisture—underwent third-party safety evaluation at the CNAS-accredited Guangzhou Jianeng Laboratory (L7417), under report numbers H2506492E-3 and H2507127-1E. Testing included ocular irritation, skin compatibility, sensitization and microbial limits, as well as assessment of misting behavior during open-eye use.

The available data suggest that the product is well tolerated under repeated daily use conditions, supporting its positioning as a low-burden hydration option for everyday eye comfort.

Final Thoughts: Comfort Is Not Just About More Drops

For people managing recurrent dry eye, comfort is not only about adding more lubrication—it is also about what comes with each dose. Growing evidence shows that reducing preservative exposure, especially in high-frequency use, can play an important role in maintaining tear film stability and ocular surface health.

As preservative-free and low-burden hydration strategies continue to gain attention, everyday eye care is gradually shifting toward approaches that prioritize long-term tolerance, consistency and real-world usability, not just short-term relief.