Many contact lens (CL) wearers live with dry-eye, a condition marked by a scratchy, grainy sensation in the eyes that’s caused when the lenses deprive the cornea of oxygen and natural lubrication. To combat this effect, a team of scientists at the Terasaki Institute for Biomedical Innovation (TIBI) has developed a CL prototype that promotes tear flow when a person wearing the lens blinks their eye. Learn more about their invention here.*

Do you have CLIDE?

Contact lens-induced dry eye, or CLIDE, is experienced by 30%-50% of the world’s 140 million CL wearers. CLIDE arises when there isn’t enough tear flow getting from the lens’ outer surface to the eye surface beneath it. Consequently, excessive tear evaporation occurs, along with all the issues related to dry eye disease (DED).

If you’re part of this population, you may be familiar with current treatment options such as rewetting drops, lubricants, gels, or frequent lens replacement. There are also eyelid treatments, like warm compresses, as well as tear gland stimulation and punctal plugs (used to block the tear ducts and prevent drainage) for more severe cases. Unfortunately, these methods have drawbacks, including:

• Inconsistent effectiveness,
• Potential buildup of harmful levels of medications,
• Awkward or inconvenient application techniques that can affect compliance.

What the researchers did

According to the TIBI researchers, previous attempts at better lenses to avoid dry eye, such as graphene-coated lenses to promote moisture retention, are expensive, impractical, uncomfortable, and potentially unsafe.

In a study, published in the journal Small, the researchers tested their idea of a CL that promotes tear flow and addresses the thinning of the tear film that occurs between the CL and eye’s surface. 

• They hypothesized that a special array of microchannels would enable tear flow from the front of the lens to the natural tear film behind the lens. 
• To prove the concept, an eye blink simulator that mimics the pressure of natural eye blinking would assist flow of a microfluidic gel through the lens’ microchannels.

The CL prototype used for the experiment was cast from a special silicone polymer mixture that created high-quality, smooth microchannels. The lens was 30 times thinner than a normal lens. Special reservoirs were made at the ends of the channels for easier fluid inflow and outflow.

What they found

After multiple tests, the team found that microchannels with square cross-sections arranged in a unique circular pattern were most effective for fluid flow. 

• The study demonstrated proof-of-concept that the lens is able to channel tear flow from the lens surface to its underside to ward off dry eye.
• The team determined the tear flow was driven by an artificial blinking motion equal in pressure to that generated by natural eye blinking.

What it means

The team concluded, “This work demonstrates the feasibility of developing microfluidic CLs with the potential to help prevent or minimize CLIDE and discomfort by the enhanced transport of pre-lens tears to the post-lens ocular surface.” The next step is to test the lens in animal models and humans, they say.

Said TIBI’s Director and CEO Ali Khademhosseini, “The inventive methods that our team has employed bring a potential solution for millions of people. It is the hope that we may extend our efforts to bring this solution to fruition.”

*Terasaki Institute for Biomedical Innovation. (2023, January 31). Contact lenses to treat dry eye syndrome. MDLinx. https://www.mdlinx.com/news/contact-lenses-to-treat-dry-eye-syndrome/4uArTkaYLXomzYgG5YF0Jm