|Essilor Junior lenses feature Airwear polycarbonate with the benefit of impact resistance.|
Practitioners should be aware of the available lens features that can stand up to children’s special needs.
While it’s tempting to treat kids as a miniature version of adults when it comes to eyewear, the fact is that kids have unique needs. This means eyecare professionals (ECPs) should approach dispensing to children in distinctive ways.
The two prime characteristics of lens materials for children are clarity and impact resistance. Children are busy and sometimes unpredictable in their activities so it’s important to protect their eyes, even if they’re not thinking about it. Since children’s vision is still developing, it’s critical they have clear, crisp optics. Another consideration is weight. Most children have small, flat bridges that are not fully developed. When this is combined with a higher diopter prescription, wearing glasses can be annoying and uncomfortable. Of course the prescription’s power is another factor, but that one is not a variable; it is established during the eye examination.
Polycarbonate. Lenses made of polycarbonate pass the ANSI Z87.1 industrial safety eyewear impact standards, which make them ideal for
|Transitions lenses give children visual comfort outside with dark lenses and clear lenses when indoors.|
kids. Compared to CR-39® material, polycarbonate lenses are lighter in weight with a specific gravity of 1.22 g/cm³. Wearers of lower prescription lenses will likely not sense the visual effect of a 29 to 31 Abbe value as much as a child wearing a higher plus or minus Rx. This should be taken into consideration when evaluating prescriptions and making lens material recommendations. While polycarbonate lenses are available from many suppliers, Essilor of America, Inc. offers Essilor Junior™ lenses. This product is a way to provide Airwear® polycarbonate lenses with an anti-reflective (AR) treatment and give the wearer the benefits of impact resistance, light weight, and reflection-free vision.
Trivex. Introduced to the market in 2002 by PPG Industries, Inc., Trivex® lens material has gained popularity in the industry due to its high impact resistance, even surpassing the ANSI Z87.1 High Velocity Lens Impact Test. Trivex material has a refractive index of 1.53 compared to a
|KEY LENS TERMS
ANSI Z87.1 Standard: A test for impact resistance that involves dropping a 1-in. diameter steel ball from 50 in. above a lens and the lens surviving the impact. (There is also a high velocity test where a .25-in. pellet is fired at the lens at 150FPS.)
Abbe Value: A higher Abbe value means the spectrum of light waves passing through a lens are dispersed to a lower degree; a lower Abbe value indicates higher amounts of dispersion, which can result in the patient seeing fringes of color around objects, thereby reducing clarity.
Specific Gravity: A value that represents the relative density of an object to an equal volume of water—the lower a material’s specific gravity, the lighter and more comfortable the resulting lens will be for a given prescription and diameter.
refractive index of 1.58 for polycarbonate. This means Trivex lens material may be slightly thicker than its polycarbonate counterparts ground to the same prescription, but it has a specific gravity of 1.11g/cm³. In addition, Trivex material has an Abbe value of 43 to 45. It’s also resistant to most commonly encountered home and office chemicals, which provides an added level of lens protection. For more information on Trivex lens material, see “Trivex Goes Mainstream.”
NXT. Did you ever think that windshield material used for military helicopters would ever become an optical lens material? PPG’s NXT® lens material came from that very beginning and offers impact resistance that exceeds the ANSI Z87.1 standards. Offered in plano and Rx sun lenses, NXT has an Abbe value of 43 to 45 and a specific gravity of 1.11g/cm³, the same as Trivex material.
UV Protection. The physiological nature of a child’s eye is such that it does not have the capacity to filter UV rays in the same way an adult’s eye does. These rays in the electromagnetic spectrum are not visible and range between 100nm and 400nm. Children also spend an extraordinary amount of time outside playing and exploring. ECPs have a responsibility to educate parents about the importance of protecting their children’s eyes with the same vigilance they have in protecting their skin from the sun. If ECPs are recommending materials like polycarbonate, Trivex, and NXT, UV protection is built into these materials so the patients’ eyes are automatically protected.
Photochromic Lenses. During the summer months, children are in and out of the house all day long. They also spend time outside at recess then return to the schoolroom. These varying light conditions present a unique challenge in giving the child visual comfort outside with dark lenses and clear lenses when they return to an indoor environment. Offered by many suppliers, Transitions® lenses come in a variety of lens materials, including all the impact-resistant lens materials mentioned.
|Carl Zeiss Vision’s PureCoat AR is ideal for children who spend a lot of time using computers, video games, and other electronic devices.|
Because of this, photochromic lenses are the perfect solution for children.
AR Treatment. An AR treatment eliminates lens surface reflections and enhanced contrast, which improves visual acuity for the patient. This is important when working in low light situations and for night vision. Children also spend a lot of time on computers, both at school and at home, as well as playing with video games and other handheld electronic devices. These activities can create eyestrain and fatigue. Lenses with a premium AR treatment substantially reduce lens reflections under these conditions, making the wearer more comfortable. Some examples of AR treatments for children include the Carl Zeiss VisionInc.’s PureCoat™, Essilor’s Crizal Sapphire™, HOYA VISION CARE, North America’s HOYA SUPER HiVision™ EX3, and Shamir Insight, Inc.’s Glacier Plus™.
Children participate in myriad outdoor activities so having good quality prescription sunwear makes perfect sense. Parents who invest in sunwear for their children will find their kids will not only be more comfortable when participating in their favorite activities, but may also perform better because they can see better and are more visually comfortable.
Polarized lenses shouldn’t be thought of as an “adult only” option. For the family who skis together or boats together, the parents have probably been aware of the benefits of polarized lenses for years, but may not know that polarized lenses are also an option for their children. Polarization reduces the blinding glare that can occur when light bounces off shiny reflective surfaces such as water, snow, grass, and asphalt. Many labs can create prescription polarized lenses using products like Xperio® by Essilor and NuPolar® by Younger Optics.
Asking questions about your pediatric patients’ activities, such as time spent on a gaming system or computer, and time spent outdoors can help you make appropriate recommendations. Educating parents about the benefits of appropriate lens materials and treatments can ensure everyone is happy with the purchase.
Joy L. Gibb is the owner of Eyes Of Joy Mobile Optical Service in Woods Cross, UT.
WHERE TO FIND IT
Carl Zeiss Vision Inc.
800-358-8258 • zeiss.com/lenses
Essilor of America, Inc.
800-542-5668 • essilorusa.com
HOYA VISION CARE, North America
877-528-1939 • hoyavision.com
PPG Industries, Inc.
800-323-2487 • ppgtrivex.com
Shamir Insight, Inc.
877-514-8330 • shamirlens.com
Transitions Optical, Inc.
800-848-1506 • transitions.com
800-366-5367 • youngeroptics.com