When patients wear contact lenses, comfort can be just as important as visual clarity and ease of care. The wettability of a lens, or the wetting agents used in their production or care, can directly impact this.
With the recent release of the Tear Film & Ocular Surface Society (TFOS) Dry Eye Workshop (DEWS) III report, it’s worth revisiting some of the available information on contact lens wetting. This article will review the different wetting agents used by various lenses, how they work, and which patients can benefit from their incorporation.
The US Centers for Disease Control and Prevention (CDC) states that there are roughly 45 million contact lens wearers in the US as of 2025.1 These wearers range from young high schoolers with pristine ocular surfaces to middle-aged adults with multiple hours of screen time in a dry work environment, to those affected by seasonal allergies, and all walks in between.
Revisiting TFOS, in the 2013 report on contact lens discomfort, they referenced that 12 to 51% of lens wearers drop out of contact lens use, with discomfort as one of the leading reasons.2
What is wettability?
The wettability of a lens can be thought of as how well the lens is hydrated as well as its ability to stay lubricated during wear.3 This can of course be evaluated on-eye using the slit lamp and assessing tear breakup speed and location.
Looking at the tear layer over the lens following a blink can help us identify problem areas. Imbalances or incompatibilities with the natural tears, the contact lens, the atmosphere, and lens products can alter this real-world interaction.
Understanding the role of wetting angles in contact lenses
Wettability can also be evaluated in lens research and development by measuring the wetting angle of a contact lens.4 This value objectively measures the angle between a drop of liquid over the surface of the contact lens.
Higher angles are attributed to poorer wetting interfaces and less spreading of the liquid over the surface. Conversely, a lower wetting angle represents an interaction that promotes smoothing of the water over the whole lens surface and provides a more hydrated and stable layer.
Figure 1: Depiction of a high wetting angle liquid (ϴ on left) versus a low wetting angle liquid (ϴ on right) over a contact lens.
A lens that has poor wettability will make the tears seem to bead off the front of the lens like raindrops on a windshield. Rather than spread over the surface of the contact, they will bubble up in small areas after a blink.
While not routinely used over soft lenses, vital dyes like fluorescein can sometimes highlight a streak-like pattern that may indicate the tears are not spreading as fluidly as a well-hydrated lens would allow.
To learn more about how to use vital dyes in clinical practice, check out True Colors: What Dyes Reveal in Ocular Disease with Cheat Sheet!
Implications of wetting agents in clinical practice
As clinicians, understanding the materials and wetting agents incorporated into contact lenses helps us better match patients with lenses that meet their comfort goals. The various wetting agents can be added to lenses and their surfaces during the manufacturing process.3 Some companies integrate the agent into the lens itself so that it can be slowly released during lens wear.
Depending on the lens modality and material, some multipurpose lens solutions also incorporate the wetting agent(s) to have further interaction with the lens when manually rubbed on the lens during the cleaning process. This in turn decreases the wetting angle and improves wettability of the lens.
Types of wetting agents
There are currently a few widely used wetting agents available on the market, including:
- Polyvinyl alcohol (PVA)
- Hyaluronic acid (HA)
- Polyvinylpyrrolidone (PVP)
- Polyethylene glycol (PEG)
An individual agent may be selected for its performance with a specific lens material, its ability to be incorporated into the lens or added to the surface only, and other considerations.
To learn about how some of these wetting agents are used in artificial tears, read the article A Closer Look at What's Really In the Artificial Tear Bottle with Cheat Sheet!
Polyvinyl alcohol
PVA is a synthetic water-soluble agent that can be found in a number of soft lens options, lens cleaners, and over-the-counter wetting drops. When found in a contact lens formula, PVA can be released from the lens material throughout the day by the patient blinking.5
Alcon’s Dailies AquaComfort Plus line of lenses contains PVA that is released with their Blink-Activated design. As the wearer blinks, some of the PVA components are released into the tear film. The PVA that mixes with the tears allows for prolonged hydration of the lens surface and extended comfort as it is worn.
Hyaluronic acid
HA is a natural polymer that contains multiple hydrophilic units.6 Similarly to PVA, hyaluronic acid can be utilized in many ways. It can be incorporated in the lens surface and body as well as perform a releasing function during lens wear.
Cleaning solutions such as Bausch + Lomb’s BioTrue Hydration Boost also take advantage of HA as an effective way to re-establish the moisture properties of lenses that are reworn. HA is further unique since it is quite similar to the endogenous HA of humans, making it a very safe option for many patients.
Polyvinylpyrrolidone
PVP is a wetting agent commonly used in lenses manufactured by Johnson & Johnson. This polymer is amphiphilic, meaning it is both hydrophilic and lipophilic.7
When this agent is bound or integrated into the lens it can, in a sense, recreate the mucin layer of the natural tears. This allows the tear film to smooth over the body of the lens evenly and improve lens comfort and decrease irritation during blinking and lens wear.
Polyethylene glycol
PEG coatings are commonly found in products that bind to the surface of rigid lens materials. This creates a hydrophilic mucin layer between the tears and the ocular surface. Similar to our natural mucin layer, this works to provide a stable base layer for the aqueous tear layer to bind to and provide a more hydrated lens surface and improve comfort during wear.
Hydra-PEG is a very popular product that can be incorporated into the surface of rigid gas permeable or scleral lenses.8 Tangle Boost is a hard lens solution that is available by prescription and can be used by lens wearers to extend the life of their Hydra-PEG coating.
Considerations for wetting agent recommendations
Evaluate contact lens patients for ocular surface disease
When it comes to selecting or recommending a wetting agent(s) for our patients, there are a few considerations. If the patient is experiencing lens discomfort or dryness complaints, a dry eye evaluation should be performed to identify the type of dryness that is occurring.
Eyes that demonstrate signs such as reduced tear breakup time, a low tear meniscus, or poor meibomian gland performance may benefit from dry eye management as well as wetting agent considerations.
Careful evaluation of the contact lens and its surface can indicate tear film instability or areas of improvement as well, and new lenses or hydration systems can be very beneficial. However, if there is a disorder of the tear film or evaporative ocular components, then these may persist following a change in wetting agent.
It’s important to remember that changing or adding a wetting agent may be part of the solution, but addressing any underlying dryness components is also essential.
Match patients with the optimal wetting agent
Each wetting agent has its strengths and weaknesses depending on a patient’s goals for their contact lens wear and their environment. Careful considerations should also be given to their tear film and the function of their meibomian glands.
Knowing where deficiencies lie with their natural tears can provide guidance on what properties the contact lens should improve. These factors can help guide our recommendations when it comes to lens material, brand, and wetting agents when fitting lenses.
PEG
A patient using gas permeable lenses that demonstrate poor lens wetting or lens discomfort may benefit from the usage of a PEG coating on their lenses or replenishing this layer using a solution like Tangible Boost on a recurring basis. If using a PEG-coated lens, be sure that the care and cleaning solutions used are compatible and won’t prematurely degrade the coating.
PVA
PVA can provide hours of comfortable lens wear thanks to its ability to diffuse its hydrophilic components into the tears. If a patient is a rapid blinker, then lenses utilizing PVA may not be a good option as the wetting agent may be expended too early.
Similarly, if a patient has extended screen usage or does not blink often, then the PVA may not be released enough during use to provide adequate comfort.
HA
The biocompatibility of HA makes it a very gentle incorporation for many patients. For those who have suffered from allergic reactions to certain ingredients or lenses, HA may offer relief. HA tends to have a higher viscosity as well, which can allow it to hydrate longer for certain individuals or in certain formulations such as artificial tears.
PVP
PVP can be a fantastic option for patients who have poor comfort with other lens materials or continue to have lens awareness when blinking. As this agent provides a stable tear base, patients who suffer from aqueous deficiency may struggle with PVP lenses, as it does not necessarily supplement this layer of their tears.
Next-generation contact lenses
Lenses of the future may take further advantage of the wetting agents already in use. The uptick in dry eye awareness and management may indicate that materials will continue to be investigated that cooperate with the human body to replicate our natural tears. Since everyone’s tear composition is unique, materials that closely mimic natural tear properties may better support long-term comfort.
Further, the properties by which the above agents work can also be expanded upon. As we mentioned, PVA can be released from commercially available lenses when they’re worn during the day. Many corporations have already begun incorporating or investigating ways that medications may be integrated into lenses.9
Moreover, a patient who can wear their contact lenses and receive their glaucoma or allergy medication drops simultaneously may be a game-changer for certain people.
Conclusion
As we discussed, there are already a multitude of wetting agents available in contact lenses, contact solutions, and eye drops.
Understanding what these components are, how they interact with one another, how they affect our patients, and who can benefit most from the various options will allow us to better care for our patients and keep their comfort front of mind.
When patients stay comfortable in their lenses, they’re far more likely to continue wearing them, and that’s a win for both them and their providers.
