The Science Behind Tangible Hydra-PEG

March 15, 2018

The Problem

More than 45 million Americans wear contact lenses, and more than half report dry eyes and discomfort. In fact, up to 20% of contact lens patients drop out each year, and dryness is the most common culprit. Many of these patients frequently experience dry eyes, without suffering from clinical “dry eye disease.”


One of the biggest reasons for discomfort is a non-wetting lens. Inadequate wettability decreases comfort, diminishes visual clarity and affects a patient’s overall lens wearing experience.


In addition, most people don’t realize that the surface of a contact lens is actually rough and covered with microscopic ridges and valleys, which the human eye can’t see, but can feel.


When the eyelid doesn’t glide smoothly over the lens, this creates irritation, excessive blinking and red eyes. The problem goes beyond comfort, becoming an inconvenience when patients must carry artificial tears or wetting drops and clean their lenses multiple times a day in an attempt to improve their comfort.

The problem is magnified for the 3 million patients who wear custom contact lenses, who represent approximately 10% of all contact lens patients. Most custom contact lens materials are inherently hydrophobic and repel water. As the eye itself has high water content, a hydrophobic lens can cause significant discomfort. Introducing any contact lens to the eye disrupts the lipid layer, increasing the tear evaporation rate and reducing the overall thickness of the tear film. Contributing to further discomfort, some patients may produce excessive lipids in their tear film, which may deposit onto the lens and create a foggy, hydrophobic surface that feels rough in the eye.

Our solution…Tangible Hydra-PEG!


After talking with countless eye care practitioners and their patients and hearing that discomfort and dry eyes were their number-one complaint, we decided to focus on creating a more comfortable lens wearing experience.


Rather than add water to lens material as many other eye care companies were doing, we took a novel approach and created a contact lens coating designed to mimic the eye’s environment and respect how the eye naturally keeps itself wet and comfortable.

See how wet Tangible Hydra-PEG makes lenses

We based our coating on polyethylene glycol, known as PEG, a substance used in ocular lubricants for decades. PEG is known to improve lens surface wettability, which improves tear breakup time, increases lubricity (the smooth feeling of the eye) and reduces deposits on the lens. The proprietary Tangible Hydra-PEG coating is a 90% water, PEG-based formulation incorporating two different polymers.


The coating is designed to fill the microscopic pits on contact lenses and build up into a smooth, wet layer that is permanently bonded to the surface of the lens. This effectively shields the tear film from the hydrophobic lens material so that the only thing exposed to the ocular surface is a hydrophilic, very wettable and smooth surface that closely matches the natural environment of the eye.

The top images show the surface quality of an untreated silicone hydrogel lens following eight hours of lens wear at 0, 5, and 10 seconds after a blink. The images below show the same patient with a Hydra-PEG treated lens following eight hours of lens wear. 

Tangible Hydra-PEG should not be confused with plasma treatment. Plasma treatment is an older process that can temporarily increase the wettability of a lens surface by cleaning it; however, the underlying lens material is unchanged and the effect wears off as soon as the patient handles the lenses with their fingers. Tangible Hydra-PEG, on the other hand, wraps the lens in a layer of protective and durable polymer gel that is highly wettable and designed to continue to provide benefit over time.


Early patient experiences with Tangible Hydra-PEG coated lenses show clear benefits:

  • Patients preferred Tangible Hydra-PEG coated lenses to their usual lenses 14-1.

  • More than 4x more patients felt the coated lenses improved their end of day comfort when compared to uncoated lenses.

  • Coated lenses were rated as approximately 3x more wettable than uncoated lenses.

  • Almost 3x more patients reported an improvement in lens fogging using coated lenses as compared to uncoated lenses.


See how Tangible Hydra-PEG repels deposits

How Tangible Hydra-PEG is applied to contact lenses


Today, Tangible Hydra-PEG is available for custom contact lenses, including corneal, scleral and hybrid lens designs. Eye care professionals prescribe and order the lenses to be coated with Tangible Hydra-PEG through their laboratory. In the lab, the lens undergoes the Tangible Hydra-PEG application process once it has been lathe-cut to specification. 


Here’s the process:


  • Lathe Cut Lens – Labs first lathe the lens per parameters specific to the patient, just as they normally would.  Tangible Hydra-PEG does not affect the lens design or fit for the patient.

  • Activation - The lens surface is cleaned and activated so it will covalently bind to the Tangible Hydra-PEG polymers.

  • Extraction/Hydration - The lenses are then soaked in the Tangible Hydra-PEG polymers, permanently bonding them to the activated lens surface.

  • Completion – The resulting lens is completely encapsulated with the Tangible Hydra-PEG polymers, resulting in a surface with optimal wettability, lubricity, tear film stability and deposit resistance.


How to get Tangible Hydra-PEG


Eye care professionals: Most labs that make custom contact lenses offer Tangible Hydra-PEG, so it is easy for you to request it for your patients. Simply ask your lab for coated lenses. The coating does not affect lens DK, design or fitting requirements.


Patients: If you wear custom contact lenses and could benefit from more comfort, convenience or longer wear time, ask your doctor about ordering a pair coated with Tangible Hydra-PEG.



Care tips


Research shows that 40-90% of contact lens wearers do not properly follow care instructions. However, contact lenses coated in Tangible Hydra-PEG require special care to maintain their long-lasting benefit, so it is important to strictly follow the care instructions. Please review Care Tips here



What’s next?


There is a great deal of science behind Tangible Hydra-PEG, and we look forward to introducing additional products to our family throughout the year.  New offerings will include a special cleaning solution for Tangible Hydra-PEG coated lenses and a monthly conditioner to refresh the coating, both designed to optimize durability of the coating. In addition, we plan to partner with other eye care companies to introduce Tangible Hydra-PEG coated disposable lenses, which will expand the benefits of the coating to a much larger group of contact lens wearers.