Contact Lens Case Reports
Contact Lens Dryness and Discomfort with SiHy Lenses
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
Contact lens surface properties (i.e., the frictional properties of the material, wettability, and deposition characteristics) are crucial to long-term contact lens comfort. Modern silicone hydrogel (SiHy) lenses incorporate wetting agents (on the surface or within the polymer matrix) to help improve the lens interaction with the tear film, ocular surface, and eyelids. But is this sufficient for all of our patients?
At the 2015 Global Specialty Lens Symposium, we presented a poster titled “Hydra-PEG: A Solution to Contact Lens Discomfort?” that described a new surface treatment for contact lenses (Caroline et al, 2015). Hydra-PEG (Ocular Dynamics, LLC) is a 90%-water polyethylene glycol (PEG) polymer that can be permanently bonded to the surfaces of both soft and GP lenses. The coating encapsulates the core contact lens with a mucin-like hydrophilic shell to help improve surface wettability and deposit resistance (Figure 1).
Figure 1. Hydra-PEG is a surface polymer that creates a mucin-like hydrophilic surface to contact lenses.
The poster describes 24 habitual soft lens wearers selected for their self-reported symptoms of lens dryness and discomfort. The subjects were fitted with two different pairs of the same SiHy lens. One pair was treated with Hydra-PEG, and the other was left untreated. The lenses were worn daily for seven consecutive days and disinfected at night with a hydrogen peroxide system. The subjects rated their lens wearing comfort (1 = poor to 10 = excellent) at three time intervals: after morning lens application, midday, and at the end of the day (Figure 2).
Figure 2. In this study, the Hydra-PEG treated lenses showed, on average, a 2.8 differential in end-of-day comfort.
Additionally, a topographer was used to visualize the tear breakup over the surface of the lenses (Figure 3). The top images show the surface quality of an untreated SiHy 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.
Figure 3. The surface quality following eight hours of lens wear at 0, 5, and 10 seconds after a blink for untreated (top) and treated (bottom) lenses.
These data appear to indicate that the Hydra-PEG surface polymer has the potential to dramatically improve contact lens wearing comfort in individuals experiencing symptoms of lens dryness and discomfort with current SiHy lenses. CLS
For references, please visit www.clspectrum.com/references and click on document #234.
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant for Contamac. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.