A Closer Look at UV-Blocking Contact Lenses
UV - BLOCKING CONTACT LENSES
A Closer Look at UV-Blocking Contact Lenses
Clinicians discuss the different levels of UV protection, the need to create demand for UV-blocking lenses and how to identify the best candidates.
Dr. Cohen: Because doctors commonly prescribe eyeglasses that have built-in ultraviolet (UV) light protection, one would think they'd do the same when it comes to contact lenses. Why is this not the case?
Dr. Nichols: Most ophthalmic and optical materials used for eyeglasses offer significant protection against UV radiation. CR39 has a cut-off at 350 nanometers, completely protecting against UVB and, to some extent, UVA rays.1 Polycarbonate completely protects the patient from all UV radiation, regardless of whether a tint is used. Contact lenses are different. Some offer little to no UV-radiation protection, while others provide adequate additional protection as a supplement/compliment to sunglasses. Contact lenses that offer protection are labeled as Class 1 and Class 2. The different classes indicate the level of UV protection. However, only three lenses are Class 1 (ACUVUE® OASYS™, ACUVUE® ADVANCE™ and ACUVUE® ADVANCE™ for ASTIGMATISM), and only a handful of others are Class 2. Class 1 lenses block 96% of UVA rays and 100% of UVB rays. Class 2 lenses block 70% of UVA and 95% of UVB radiation.
|"Some [contact lenses] offer little to no UV-radiation protection, while others provide adequate additional protection as a supplement/compliment to sunglasses."|
— Jason J. Nichols, OD, MPH, PhD
Class 2 is better than not having any UV protection. However, I think it's important to use the Class 1 materials whenever possible.
Dr. Bergmanson: Although the three Class 1 contact lenses block up to 90% of UVA rays, we'd like to see an improvement. The ideal contact lens would mimic the crystalline lens absorption curve. We applaud those manufacturers who are improving their products. However, we haven't arrived quite yet with the ideal lens. Evidence shows that short wavelength blue light can harm the photoreceptors in the retina,2,3 and this could be the source of radiation that causes age-related macular degeneration (AMD), but we don't have that evidence yet. However, some intraocular lens manufacturers now are marketing implants that block blue light. Down the road, we may see this filter developed for contact lenses, particularly if we establish that blue light is a risk factor for AMD.
Dr. Nichols: Most styles of sunglasses don't prevent all UV rays from reaching the eyes because direct and reflected sun light can shine through the sides, top and bottom of eyeglasses. This is known as the Peripheral Light Focusing Effect (PLF).4 Studies have shown that UV-blocking contact lenses can also help block the peripheral light that sunglasses can't block.4,5
UV rays can enter from the side, top and bottom of sunglasses, known as the peripheral light focusing effect. These peripheral rays may be more dangerous than those entering from the front. UV-blocking contact lenses block these peripheral rays.
Dr. Bergmanson: Our team in Houston was the first to show that soft contact lenses, when combined with UV-blocking sunglasses and other protective headwear, can help protect against harmful UV radiation that would otherwise pass through the cornea and into the eye because they cover the limbus and palisades of Vogt. Contact lenses protect the vital stem cells of the cornea that reside in this region. Wrap around sunglasses come close to offering the same level of protection against UV rays that penetrate the corneal region tangentially and temporally.
Dr. Newsome: In light of that research, we need to prescribe UV-blocking contact lenses, sunglasses and spectacle lenses, as well as a wide-brimmed hat, 1 inch or more in front of the eye.
ARE ALL CONTACT LENSES CREATED EQUAL?
Dr. Cohen: In the past, many patients believed, and some still believe, that all sunglasses are equally effective. However, we know this isn't the case in terms of quality and protection. The same principle applies to contact lenses.
Similarly, most patients believe all contact lenses are the same. Yet, we know their UV-blocking capabilities are different as we mentioned. To date, of all the contact lenses on the market, ACUVUE® OASYS™, ACUVUE® ADVANCE™ and ACUVUE® ADVANCE™ for ASTIGMATISM are the only lenses that have received the American Optometric Association's and the World Council of Optometry's Seal of Acceptance for UV-absorbing contact lenses*. Do certain lenses do a better job than others?
Dr. Nichols: We don't have guidelines from the American National Standards Institute (ANSI) for contact lenses, as we do for ophthalmic lenses. However, the FDA has guidelines that mirror the ANSI standards, allowing us to label contact lenses as "UV-blocking."
Contact lenses that offer protection against UV rays are labeled as Class 1 and Class 2. Class 1 lenses block 96% of UVA and 100% of UVB rays. Class 2 lenses block 70% of UVA and 95% of UVB rays.
Dr. Bergmanson: James E. Walsh, PhD, and I have published research to validate this recommendation.5 We showed that existing UV-blocking contact lenses reduce the eye's exposure to UV radiation to safe levels. (This study was done before the introduction of the two most recent silicone hydrogel UV-blocking lenses, which have improved UV-filtering properties.)6
Although the UV-blocking contact lenses discussed in the study didn't filter UV as efficiently as some sunglasses, they're still worth recommending to patients.
Dr. Cohen: How have you incorporated UV-blocking contact lenses into your practice?
Dr. Newsome: Based on my patients' needs and data, UV-blocking lenses are my lenses of choice unless patients request other options. If patients request a different lens, I inform them that the lenses don't offer added protection from UV rays.
Dr. Cohen: One of the obstacles the contact lens industry faces is that doctors don't ask for lenses with UV-blocking features, which suggests there's little demand for them. How much of the responsibility belongs to industry, and how much rests with practitioners?
Dr. Newsome: Industry needs to play a role, no doubt, but practitioners have the primary responsibility of creating demand by educating their patients.
Dr. Nichols: I advocate the use of a UV-blocking contact lens for patients and students whom I teach. In some cases, though, prescribing a lens with UV protection can be a challenge because we are still left with limited options. This is where industry must provide a wider variety of lenses.
Dr. Cohen: Some clinicians suggest identifying only at-risk individuals so we can identify potential candidates for UV-blocking contact lenses. Dr. Nichols, you've supported taking a global approach to determining candidates, rather than focusing on only certain eye and pigmentation issues. Is that a radical view or one we should encourage all of our colleagues to embrace, just as we would encourage them to prescribe UV-blocking sun wear for all patients?
Dr. Nichols: I believe we should prescribe UV-blocking contact lenses for the entire population, unless the patient is spending his or her entire life indoors. My younger patients are especially at risk because the ophthalmic UV-filtering capabilities of their crystalline lenses are less efficacious at a young age. And they don't necessarily make appropriate health decisions.
For older patients, I recommend UV-blocking contact lenses because of:
■ Aphakia or an intraocular lens
■ Diseased corneas
■ Post refractive surgery care needs
■ Occupational risks, such as construction work
■ Nonsolar exposures, such as welding.
Dr. Cohen: That covers just about everyone. And that doesn't sound like such a radical concept to me. CLS
|* ACUVUE® Brand Contact Lenses help protect against transmission of harmful UV radiation to the cornea and into the eye. WARNING: UV-absorbing contact lenses are NOT substitutes for protective UV-absorbing eyewear, such as UV-absorbing goggles or sunglasses because they do not completely cover the eye and surrounding area. You should continue to use UV-absorbing eyewear as directed. NOTE: Long-term exposure to UV radiation is one of the risk factors associated with cataracts. Exposure is based on a number of factors, such as environmental conditions (altitude, geography, cloud cover) and personal factors (extent and nature of outdoor activities). UV-blocking contact lenses help provide protection against harmful UV radiation. However, clinical studies have not been done to demonstrate that wearing UV-blocking contact lenses reduces the risk of developing cataracts or other disorders. Consult your eyecare practitioner for more information.|
- Pitts DG, Klein RN. Environmental Vision: Interactions of the Eye, Vision and the Environment. Stoneham, Mass. Butterworth-Heinemann; 1993:274.
- Ham WT, Mueller HA, Ruffolo JJ, et al. Action spectrum for retinal injury from near-ultraviolet radiation in the aphakic monkey. Am J Ophthalmol. 1982;93:299-306.
- Ham WT, Ruffolo JJ, Mueller HA, et al. Histologic analysis of photochemical lesions produced in rhesus retina by short wave-length light. Invest Ophthalmol Vis Sci. 1978;17:1029-1035.
- Kwok LS, Kuznetsov VA, Ho A, et al. Prevention of the adverse photic effects of peripheral light-focusing using UV-blocking contact lenses. Invest Ophthalmol Vis Sci. 2003;44:1501-1507.
- Walsh, JE, Bergmanson JP, Wallace D, et al. Quantification of the ultraviolet radiation (UVR) field in the human eye in vivo using novel instrumentation and the potential benefits of UVR blocking hydrogel contact lens. Br J Ophthalmol. 2001;85:1080-1085.
- Walsh JE, Koehler LV, Fleming DP, Bergmanson JP. Novel method for determining hydrogel and silicone hydrogel contact lens transmission curves and their spatially specific ultraviolet radiation protection factors. Eye Contact Lens. 2007;33:58-64.
Contact Lens Spectrum, Issue: November 2007