Modern Contact Lens Materials and Modalities

In today’s competitive and consumer-based market, there is a vast selection of contact lenses to choose from. Monthly or daily disposables, hydrogel or silicon hydrogel, continuous vs daily wear – these can all be very confusing and difficult to understand.

When it comes to replacing your prescription soft lenses, most are approved for either one month or one day of wear and then be thrown out. One lens is approved for bi-weekly replacement (Acuvue Oasys). Monthly or bi-weekly replacement lenses are to be thrown away 30 or 14 days, respectively, after opening the package. Once the package is opened, the lens is susceptible to material degradation and microbial contamination. When the lenses are not being worn, they must be stored properly in a solution that is approved to store soft contact lenses. There are hydrogen peroxide based solutions as well as multi-purpose solutions for wetting, cleaning, and storing.

Daily disposable lenses are surging in popularity in North America, and for good reason. This lens modality offers the most convenient, comfortable and hygienic contact lens experience. Daily disposable lenses do not require solutions for wetting, cleaning, or storing, which saves time and money for patients. Contact lens dryness and discomfort is the leading cause for patients to stop wearing their lenses – most daily disposables easily outperform their monthly disposable counterparts in these categories simply due to being a fresh lens, which wets much more easily.

Lens materials have evolved greatly since contact lenses first started being worn. From uncomfortable rigid materials that didn’t provide the cornea any oxygen, to soft and wettable materials that allow the cornea sufficient oxygen even when sleeping, the science of contact lenses has really exploded in the last couple decades. The first soft contact lenses were made of a material known as hydrogel, which is still used in some lenses today but less and less frequently. Many of these lenses are permeable enough to oxygen that the cornea receives enough during waking hours, but none of these are approved for wearing while sleeping.

Silicone hydrogel lenses are similar to their predecessors but with the major advantage of high oxygen permeability. Many contact lens complications contributed to low oxygen availability to the cornea are fortunately becoming much less common. Some silicon hydrogel-based contact lenses are even approved for sleeping with them still on the eye (known as continuous or extended wear). However, sleeping with contact lenses, even ones approved for continuous wear, is much riskier as the chance of infection is much higher, though still overall quite low.

Contact lens material overhauls don’t end with just increased oxygen permeability. The monthly disposable lens Air Optix has incorporated a molecule called Hydraglyde into the contact lens material itself to help improve dryness and discomfort. Dailies Total One is a daily disposable lens that has a “water gradient” which transitions from approximately 99% water content on the front & back surfaces of the lens (which is great for comfort) to 33% in the center (which is great for oxygen transmission).

Some companies have aggressively marketed contact lenses to the consumer via television and online advertisements, but the marketing can be deceiving. For example, we’ll compare two different daily disposable contact lenses that are frequently being advertised presently: Dailies Total One and Hubble. Hubble Contacts use an old hydrogel material called methafilcon A as a daily disposable lens. The material itself was used in a contact lens by CooperVision which has discontinued its production in order to further expand their line of contact lenses with improved comfort, performance, and safety. Hubble markets the lenses as affordable and convenient, but when shipping, subscription is taken into account, the price is very similar to far superior lenses such as Dailies Total One with applicable rebates and offers. As always, talk with your optometrist about the latest technologies, and how you can experience the safest, most comfortable contact lens experience possible given your specific needs…and don’t fall prey to deceptive marketing strategies!