Children Need Sunglasses

By Katheryn Dabbs Schramm, FNAO, ABOC

Throughout life, environmental variables such as proximity to the equator, higher elevations, reflective ability of the ground surface and mid-day exposure, increase the risks of developing sun-related eye disease. Although the effects of sun damage may not become apparent until much later in life, the first decade of life, when the lens of the eye is most transparent, may represent the period of greatest exposure. And, at no other time in life are we as prone to the lasting effects of the sun’s rays, than in infancy. To understand the increased risk to infants and children, we must examine the changes in lens transparency that occur and the relationship of light to ocular damage.

CHANGES IN LENS TRANSPARENCY FROM BIRTH TO AGE 25 YEARS
At birth, the lens of the human eye is almost 95 percent transparent and remains quite clear for the first decade of life. As the crystalline lens gradually loses transparency and begins to yellow, the amount of UV penetrating the lens decreases. By age 25, less than 20 percent of UV rays reach the retina.

THE RISKS—LIGHT AND OCULAR DAMAGE
Light or electromagnetic radiation is categorized by wavelength. The optical spectrum includes ultraviolet, visible and infrared light.

• Ultraviolet (UV) light has a wavelength shorter than 400nm; some believe that wavelengths to 450nm are hazardous.
• Visible light wavelengths range from approximately 380nm to 760nm.
• Infrared (IR) light has wavelength longer than 760nm.
  

Ultraviolet—UV light is further subdivided into UVA, UVB and UVC. The shorter ultraviolet wavelengths are most harmful.

• UVA ranges from 320 to 400nm (as defined by ISO and SAA) and represents the longest UV wavelength with the highest energy. While single doses of UVA are less damaging, an accumulation has been associated with cataracts and long term changes to cell layers, especially in the skin around the eyes. The Queensland Institute for Medical Research reports that most damage from UVA occurs before age 30. The proceedings from the National Academy of Science states that compared to UVB, UVA rays cause a larger number of mutations in the deep layers of skin where tumors appear.
• UVB ranges from 290 to 320nm, cause sunburn and other burns to the lids and related structures and is thought to have carcinogenic effects on the skin. It also has been linked to cataracts and other retinal problems.
• UVC ranges from 200 to 290nm would be the most harmful, if it were not filtered out by the earth’s ozone.

The cornea absorbs ultraviolet light in the lower ranges. The crystalline lens of an adult eye absorbs ultraviolet light between 300 and 390nm. It is estimated that 50 to 80 percent of the lifetime exposure to ultraviolet occurs by the age of 18 years. Prior to age five, there are not enough chromophores (parts of a molecule responsible for its color) in the lens of a child. Because the lens of a child is so transparent, it does not filter the ultraviolet with the efficiency of the adult eye. As the eye matures, UVA is absorbed and converted, which turns the lens slightly yellow. After a lifetime of absorption, the lens may be significantly yellow and require removal (brunescent cataract).

Visible light—The length of the light wave striking the retina determines the colors that make up the visible spectrum. Blue and blue-violet light are the most damaging to the eye, especially when combined with UV or IR. While the cornea and crystalline lens absorb some of the ultraviolet, high percentages of blue light still pass through. UV and blue light cause cumulative damage to retinal and skin cells.

It is commonly accepted that intraocular lenses (IOLs) should incorporate UV protection, but the benefit of tinting the IOL to block blue light remains controversial. Lenses that block portions of the visible spectrum also affect color perception and diminish night vision. So, as more children receive IOLs, this becomes increasingly problematic. Adequate lighting is essential to proper visual development, yet that same light may increase the eventual likelihood of retinal damage.

Infrared—These longer wavelengths have been thought to be the least damaging as much of infrared light is absorbed by the cornea and lens, and does not reach the retina. However, there is a suggestion that damage to the eye may occur from a combination of IR and UV.

Polycarbonate and Trivex lenses are the most impact-resistant lenses available and are the only lenses recommended for children’s sunglasses. These lenses offer a natural UVA and UVB inhibitor and can be tinted to the desired density and color. In addition, these materials are available polarized and in photochromic. Polarized polycarbonate and Trivex lenses are an excellent choice for children. Water, sand and cement are significant sources of reflected glare and young children are frequently exposed to all three. Today’s polarized lenses block harmful ultraviolet light and can selectively attenuate harmful blue light. Since polarized lenses reduce reflected glare, and scatter (Rayleigh’s effect) children may suffer less discomfort and have reduced eyestrain.

Photochromic lenses have come a long way over the last several years. These lenses change more readily and the versions now available in poly-carbonate fade in about half the time of the plastic counterpart. Children seldom will switch from indoor glasses to sunglasses without parental assistance and/or insistence. Since photochromic lenses automatically adjust in proportion to the intensity of the light, they are an excellent choice for children at a time when they are most vulnerable.

Lens Colors—Absorptive lenses are classified by two variables: the lens color and the lens transmission or density. For example, a G-15 lens is gray-green in color and has a visual transmission of 15 percent. There are only two colors of lenses suggested for general pediatric use, gray and brown.

The lens-of-choice for most children is gray-gray or gray-green with an absorptive value of 70 percent. The gray color of the lens provides even color transmission throughout the visual spectrum for more natural color rendition, and in polycarbonate and Trivex, offers excellent absorption of UV radiation. The 70 percent density recommendation is sufficient to offer adequate protection without significantly reducing acuity.

Because of its effect on blue light, brown lenses also are beneficial. As more research documents the damaging effects of blue light, the need for a brown lens becomes increasingly evident. Children at higher risk for macular degeneration may also benefit from a golden-brown, melanin lens. An absorptive value of 70 percent is also recommended for all brown lenses used on children.

Although gray and brown lenses are considered “all-purpose” lens colors, other colors may be used for special situations. For example, a medium density vermillion (cranberry color) lens is ideal for early morning snow play. This lens color increases depth perception by filtering haze and reducing glare.

Not all lens colors are appropriate for pediatric application. While gradient tints and fad colors such as pink, blue and yellow may look cute and offer some UV filtering benefit, they often reduce acuity and affect color rendition. Gray-blue lenses and green lenses are also discouraged for the same reasons. The addition of blue to a gray lens increases lens density (darkness) to an unacceptable level. A green lens will filter some blue light, but the lens has to be darkened significantly to offer comparable visual transmission to gray or brown lenses. Gradient lenses do not offer sufficient protection from reflective ground surfaces to be considered for use on children.

While polarized lenses are beneficial under most conditions, they may not be appropriate for young children first learning to snow ski. While adult downhill racers use polarized goggles, children may need some glare and contrast for safe surface discrimination. While playing in the snow, it is most important to reduce UVA and UVB while reducing glare, since about 80 percent of the UV hitting the snow is reflected.

SPECIAL EDGING CONSIDERATIONS FOR HIGHER POWER

The use of polycarbonate or Trivex lenses is not the only safety consideration when fitting children with prescription sunwear. While these lenses may protect the eye from injury, children can be injured when the frame and/or lenses are driven into the face. While accidents are inevitable, the damage can be lessened with the use of appropriate edging techniques.

Any portion of the lens that exceeds the interior eyewire of the frame poses a potential safely hazard. For plus lenses, this usually will be the upper nasal area of the glasses. Since aspheric plus lenses provide flatter curves, they are easier to edge and often produce a safer, more attractive, and more comfortable sunglass. However, even non-aspheric plus lenses should be surfaced for minimum thickness.

Surfacing a plus lens is more costly than using a stock lens; but, when dealing with the smaller eye sizes required for children, it is essential. Cutting a lens for 40 eye frame out of a 70mm blank, will create a much thicker edge and a heavier lens than acceptable. When ordering lenses from a surface lab, the desired thickness must be carefully considered and always specified. The suggested minimum edge thickness for a plus lens is 1.3mm and should not exceed 2.0mm.

Split bevels are also effective in reducing the amount of lens exceeding the interior eyewire. Reasonable splitting of the bevel is helpful in preventing or reducing injury.

Special care must also be taken with the edges of both plus and minus polycarbonate and Trivex lenses. Instead of the standard hide-a-bevel, the edges must be rolled on all higher powers.

Fitting characteristics and consideration, by age There are certain ages with similar social and physical characteristics: The infant/toddler, pre-school aged child and school aged child. Although the social issues of older children differ greatly, the physical requirements are essentially the same. Of primary concern within each aged group is the fit of the bridge. The burden of fit is always the bridge.

Infant/Toddler—A baby’s bridge has very little depth and can appear almost flat. Yet, this tiny structure must support the weight of the glasses. To do so comfortably, the bridge of the sunglass must conform exactly to the shape of the child’s nose. From infancy to aged three, the depth of the child’s bridge will increase to approximately 14mm and continue to increase as the child matures. The primary change is to the slope from the crest to the cheek.

The correct bridge will distribute the weight of the glasses evenly over the sides and top of the child’s nose while avoiding contact with the supra orbital bone and not resting heavily on the cheeks. Yet, the sunglass must be of sufficient size to limit UV exposure through the upper eyewire or from the sides. While the eye should center vertically in the frame, it should be large enough through the “A” measurement to allow approximately one years growth. When fitting an infant or toddler with sunglasses, prescription or non-prescription, the frame color will be traditional—blue for boys, pink for girls. Possible exceptions are unisex colored frames of tortoise, red or black, which can be quite striking on these young faces.

Preschool, three years through six years—Children in this age-group can be quite independent and want to make all the decisions—decisions based solely on color. Availability will limit choices, but only appropriate colors should be shown.

The correct bridge fit will still be the primary fitting concern. As with infants and toddlers, the bridge shape must be one that will distribute the weight evenly over the sides and top of the child’s nose. The child’s nose will have more depth than that of an infant, which will help the sunglass stay off the child’s cheeks. The frame should be sized to allow at least one years growth and be at least as wide as the widest part of the face.

School age, seven years through nine years—By school age, children’s opinions are beginning to be based more on their peers and far less on their parents. Frame color takes on a different role with this age group. Colors that were once in demand now may be firmly rejected. While a seven year old may want a pink sunglass, she may refuse to wear it by age eight. Whenever possible, non-gender-specific colors should be shown to insure wearing compliance for the longest time. As the child matures, it becomes increasing important to conform to their peers and older children. Brand name recognition and their influence are escalating for this age group.

Tweens, 10 years through 14 years—This is where the fun begins. Tweens generally have fully developed facial features, fully developed visual systems and fully developed attitudes and opinions. These children want to wear what older teens are wearing. Today’s tweens want brand names and their parents have more expendable income than any previous generation. They are more open to frame colors based on individual coloring, like cool colors for youth with blue undertones and warm colors for those with golden undertones. However, only popular colors are considered.

From the age of 10 years on, the shape of the child’s nose takes on far greater cosmetic importance. In the younger age groups, the primary concern is finding a sunglass frame that fits the child’s bridge correctly. But, for tweens, it is the appearance of the frame’s bridge that may determine whether or not the child uses the sunglass.

If the bridge of the frame is too high, the child’s nose will appear too long. If the bridge of the frame is quite low, the child’s nose will appear too short. If the bridge of the frame is wide, the nose will look too wide.

In addition to the appearance of the nose, the child’s brow-line and facial shape take on greater importance. Cosmetically, the sunglass frame should balance the child’s face. Approximately one-third of the face should be visible above the upper eyewire, the sunglass frame should cover one-third of the face and one-third of the child’s face should be visible below the sunglass.

The sunglass frame should be as wide as the widest part of the face. If the sunglass is too narrow through the “A” measurement, it will look too small, not offer adequate sun protection and the face will appear too full. A sunglass frame that is too wide may be uncomfortable, make a narrow face appear narrower and overwhelm small features.

Since the lenses of a sunglass are dark, the relationship of the sunglass frame to the shape of the brow is less critical than in conventional eye-wear. However, the upper eyewire must offer sufficient coverage to block uncomfortable glare and harmful sunrays, while maintaining the approximate 1/3, 1/3, 1/3 proportions.

Getting the word out—Eyecare professionals need to become advocates armed with knowledge. At the very least, babies less than six months of age should not be in the sun. Older babies should wear hats, use strollers with canopies, and whenever possible, wear sunglasses. Children who wear corrective lenses should have Rx sunglasses, clip-on sunglasses or photochromic lenses. Those children spending long periods at the beach, on the water or playing in the snow, should have sunglasses specifically designed for those activities.

Recommending from the chair—No advertising can compare in effectiveness to a recommendation from the doctor and all ECPs need to be sunwear advocates. When eyecare professionals recognize the need for sunglasses and pass that information on to the parent, more often than not, the parent follows through.

Currently in Australia, schools require hats, sunscreen and sunglasses for children playing outdoors. Started in 1981, Australia’s most recognizable health campaign is “Slip-Slop-Slap,” which recommends the use of sunglasses, protective clothing and sunscreen before going out in the sun. The original slogan of Slip on a shirt, Slop on sunscreen and Slap on a hat was extended in later years to include “Wrap—on some sunnies [sunglasses].”

In the dispensary—The dispensary should advocate sunglasses by having printed information available for the parent and small sunglasses on display. When browsing the sunglasses selection, few adults can resist picking up a tiny sunglass and asking, “Do children really wear these?” Products well placed within the dispensary indicate the office and staff are prepared to care for children.

Overcome objections—Non-prescription sunglasses remain an inexpensive commodity and when the need for sun protection is recognized, few parents can resist paying the price for prescription sun protection. The additional cost of photochromic lenses is justified by the added convenience. Clip-on sunglasses are inexpensive and may be the only reasonable option available to a parent on a limited budget or for rapidly changing prescriptions.

While any sunglass may be lost, broken or outgrown far too soon, the cost of replacement is minor when compared to costly cataract surgery or the priceless human retina. As Bill Sardi of Eye Communications once said, “Only two retinas are issued per newborn and they have to last a lifetime.”