Sep
2005

Lens Choices



The evolving challenges of vision correction for the first wave of Baby Boomers…and beyond
By By Vicki B. Masliah

For many Baby Boomers, one of the first signs they are “maturing” is receiving an AARP membership card. While some may ignore this symbolic milestone because it runs counter to their youthful self image, it’s harder to deny the inevitable changes in vision that are a natural part of aging.

With the oldest Boomers now entering their 60’s, eyecare professionals should be prepared to cater to the visual health and comfort of the growing senior population. When talking with aging Baby Boomers and seniors, it’s important for ECPs to help them understand how the proper lenses, frames and even lighting can enhance vision and improve their quality of life.
The most common complaint among seniors is probably the loss of accommodation caused by the onset of presbyopia. Explaining how a progressive lens can help the patient focus at near, intermediate and far distances is often sufficient to convince a patient to give progressives a try. The fact that progressives eliminate segment lines is a benefit that speaks for itself. For patients who are still not sold on PALs, the inconvenience of switching between two pairs of glasses for distance and near should be emphasized.

Aphakic patients can also benefit from progressive lenses. Although implants have eliminated the limitations these patients once suffered with lenticular lenses, they no longer have any accommodative ability. Progressive lenses return that lost ability. They also eliminate the image displacement caused by conventional lined multifocal segments.

Because so many seniors use computers regularly, near variable focus lenses are an ideal second pair for the presbyopic patient. Explain that the intermediate zone in a progressive lens is not adequate for wearers working at that focal length for extended periods of time. Also point out the monitor has less contrast than a printed page and its positioning does not fall within the functioning of conventional multifocals.

In addition to wearing near variable focus lenses for computer use, the lenses are perfect for doing crafts and hobbies, so many of which are performed within close focal lengths.

Although visual comfort is a priority for seniors, physical comfort is equally important. In particular, weight is a concern when selecting frames and lenses. The skin around the nose and the eyes becomes thinner and more fragile. There is less cushioning for the glasses. Heavier frames and lenses will pull at the skin, causing discomfort and irritation.

Lightweight lenses made of polycarbonate, high-index plastic or Trivex are excellent choices for seniors, especially in more extreme prescriptions. However, weight reduction is often better addressed by frame selection. Lightweight materials such as titanium as well as rimless styles combined with smaller sizes are the answer.

“The greater part of my customer base is geriatric patients,” says Paul Losseff of Holiday Opticians in Toms River, N.J. “I have found that comfort is the most important factor for them. Not only do we fit them with lightweight lenses and frames, but we are also very careful in our adjustments. We teach them to come in as soon as their frame needs adjusting, to avoid any unnecessary irritation.”
Lenses featuring aspheric designs also combine comfort with cosmetics. As prescriptions increase, the necessity for steeper base curves increases, and so does the thick bulbous appearance of the lenses. Practitioners often request flatter than appropriate bases to improve the look. Unfortunately, this causes reduced clarity in the periphery. Optical asphericity is the answer to this dilemma. The front curves for plus lenses flatten as they move toward the edge. Aspheric curves for minus powers steepen, slightly, toward the edge. Cylinder and spherical variations are introduced on the lens surface to compensate for the perceived power error. With a +5.00 sphere, best-form suggested base curve is 10.00 diopters, through which foveal and peripheral vision is equally comfortable. When a 6.50 base curve is selected, the patient will see sharply through the center of the lens. The periphery, with the eye rotated 30 degrees, is perceived as +5.50 sphere and .75 cylinder. When asphericity in introduced to the 6.50 base, the peripheral vision returns.

It should be noted flatter base curves do not thin out a lens. They are more attractive because they prevent the lens from protruding out of the frame front. Any very slight amount of weight difference in aspheric lenses results from a small amount of mass reduction of the lens material. The additional benefit of optically aspheric lenses is the more natural appearance of the eye. There is less magnification in plus lenses and less minification in minus lenses.
Beyond the lenses themselves, there are several lens treatments that further enhance the performance of lenses for the aging eye.

For example, the mature patient will become aware of a decrease in night vision. This is compounded by the fact that even white lenses will absorb or reflect about 8 percent of the light and a car windshield absorbs up to 20 percent of the available light. Some older patients will request a tint to help with the discomfort felt from oncoming headlights. However, this would be counterproductive because these patients need more light, not less. The answer is an anti-reflective coating to maximize available light, since the annoyances from headlights are largely the result of the reflections they cause.

Another reason for recommending AR is to counter the glare caused by the bright lights seniors often use for reading or close work. Also, the best lens designs for aging patients, high-index and flattened curve products, utilize curves that cast exaggerated reflections. These reflections can be significantly reduced with the application of an AR coating, enhancing the overall comfort of the lenses. Cosmetically, the loss of reflection will make for less squinting and, again, less wrinkles. The coated lenses allow the patient’s eyes to be clearly seen, adding to the total expression on their face.

There are differing opinions among dispensers about whether or not older patients should wear cosmetically tinted lenses. Light tints, compatible with the frame, create a focus on the glasses that attracts attention away from the patient’s “aging areas.” However, some believe soft colors mask wrinkles. Another school of thought is that as much light as possible should be allowed through the lens and no tint at all be used. Others say tints work counter to cosmetics because they tend to cast shadows, making wrinkles and under-eye circles appear even darker. A properly fit frame that intersects the bags or circles does a better job of disguising them.

The compromise between the opinions is a blush tint. The lens is dyed a pale tint, no more than 5 to 8 percent in density. Then an AR coating is applied. The amount of light transmission eliminated by the tint is allowed to pass through the lens by the AR coating. This makes the lens as effective as an uncoated white lens.
What practitioners do agree upon is that if the lens materials are not inherently UV absorptive, they should be given a UV treatment for the sake of protection.
Sunglasses are also essential for seniors. A good quality sunlens will absorb potentially damaging UV radiation and polarized lenses eliminate glaring and at times, blinding sunlight, an important safety factor. Sunglasses also protect the eyes and the skin around the eyes from the damaging and aging rays of the sun. Of course, less squinting means less wrinkles, a key selling point for age-conscious Boomers.

A gradient sunlens tint can also be useful for older drivers because it allows more light to be used to see the dashboard. With any sunglass, a back-surface anti-reflective coating should be applied to reduce distracting backside reflections.

As a result of an array of pathologies, the mature patient may develop light sensitivity or photophobia. Among the more common causes are developing cataracts, aphakia, macular degeneration, glaucoma and diabetic retinopathy. Even some medications cause photophobia and may increase sensitivity to glare, which in turn may reduce sharp vision and depth perception.

A beneficial treatment for light sensitivity of this sort is specialized photochromic glass or custom-dyed plastic lenses that absorb irritating light while allowing enough light to pass through for functioning vision. The colors are designed to eliminate blue light and short wavelength visible light. They enhance contrast and ease the adjustment from one visual environment to another. Different densities of absorption are appropriate for different pathologies and desired comfort. Again, in all cases anti-reflective back surface treatments should be applied.

The possibilities are virtually limitless for enhancing senior patients’ vision and comfort, while helping them maintain their youthful attitude and look. Now is the time for ECPs to customize their practice to become specialists in adult eyewear.

LT

Vicki B. Masliah is director of professional education for Hirsch Optical, an independent wholesale laboratory in Farmingdale, N.Y.

 

|