By Jeff Hopkins
Contact lens wearers want the same thing everyone else wants: to see clearly, keep their eyes healthy, be comfortable all day long. Since they were first introduced as far back as 1887, contact lenses have continually improved in all three key areas. But even today, roughly one in six U.S. contact lens wearers eventually abandons contact lenses, and a lack of comfort (also known as “awareness” of the lens on the eye) is considered to be one of the main culprits. Unity BioSync® with HydraMist® is a new premium daily disposable silicone hydrogel contact lens that, through the HydraMist Technology, brings a new level of comfort to contact lens wearers.
Two key elements of contact lens comfort are wettability and oxygen transmission. Inadequate oxygen transmission to the cornea can result in ocular surface inflammation, corneal swelling and infection, among other issues. These eye health issues reduce comfort and wearing time and may also have long term effects . Silicone hydrogel lenses are far more permeable than conventional contact lenses, allowing them to deliver more oxygen to the cornea.
However, silicone is a hydrophobic material – water droplets tend to bead up on the lens, rather than spreading out to provide a consistently moist surface. The combination of silicone and hydrogel reduce this hydrophobic effect; however, exposed areas of silicone can maintain the hydrophobic properties.
The ideal contact lens mimics the condition of the eye. Since the lens sits on the eye’s surface, it must be compatible with the eye’s physiology and chemistry – this is key both to maintaining comfort through a long day of wear and keeping the eye healthy.
HydraMist is a 90% water polymer that is permanently bonded to the lens and mimics the eye’s tear film. Based on a polymer widely used in ocular lubricants, it has several benefits that contribute to improved lens comfort and eye health:
Improved surface wettability. Maintaining consistent wetness across the lens surface reduces eye dryness and allows for longer comfortable wearing time.
Increased lubricity. Lubricity (“slipperiness”) affects how the lens moves on the eye and reduces friction as the eyelid moves over the lens during blinking. Since people blink an average of 14,000 times per day, any friction during blinking can decrease comfort, reduce wearing time, and contribute to contact lens-related red eye and other issues.
Reduced protein and lipid deposition on the lens. Improved wettability reduces deposits of lipid and denatured protein from tears. Lipid deposits can increase hydrophobicity on the lens surface, reduce clarity by making the lenses foggy, and reduce tear film stability. Proteins in the eye have natural antibacterial properties, but in contact with the lens, these properties tend to diminish. This can induce an inflammatory response in the eye, causing irritation.
Before launching Unity BioSync with HydraMist, VSP contracted with an independent testing consultant to conduct a multicenter masked, randomized crossover clinical trial. Seventy subjects compared Unity BioSync with HydraMist with three other daily disposable soft contact lenses. Unity BioSync performed well against the comparative lenses that were worn during the study period. Subjects rated Unity BioSync 9 out of 10 for overall vision, 9 out of 10 for initial comfort, and 8 out of 10 for overall comfort.
Available in Two Base Curves
A well-fit contact lens should provide full corneal coverage, good centration, and low lens lag during blinking. Many daily soft contact lenses are only available in one base curve and may not provide this ideal fit for all wearers. Recognizing this, VSP offers Unity BioSync with HydraMist in 8.8 and 8.5 base curves. Generally speaking, the 8.8mm base curve is recommended for corneas with an average K-reading of less than 42.00D. It is also recommended as the first choice for average K’s between 42.00D and 45.00D; the 8.5mm should be used if it does not provide the ideal fit. For average K’s above 45.00D, the 8.5mm curve is the recommended option . The eyecare practitioner’s expertise will determine the ideal base curve for each patient.
The Bottom Line
The contact lens that performs best is the lens that the wearer notices least. By allowing the eyes to breathe and maintain a normal moist tear film throughout a long day of wear, Unity BioSync with HydraMist virtually eliminates eye irritations that can cause wearers to remove their contacts in the course of the day or abandon contacts altogether. The only thing they will notice is their outstanding vision.
Learn more about how the two base curve options and design technology behind Unity BioSync contact lenses satisfy the criteria for successful contact lens wear with our CE, Unity BioSync Contact Lenses with HydraMist: Two Base Curves for Fit and Comfort, in this issue. This course is free, courtesy of an educational grant from VSP.