High Tech Meets Eyewear

emPower frames in charging station

by Marcia Dettloff, OD on February 25, 2011

If you follow tech news you’ve probably heard about some newfangled lenses that change power with the touch of a button.  They are aimed at the over 40 crowd that has lost their ability to change focus from distance to near, promising clear vision throughout the lens at all distances.  Although the power changing technology is impressive, I’m not convinced these lenses are ready for prime time…yet.

The Superfocus lens (formerly called Trufocals) is a combination of two lenses with a variable amount of liquid between them.  Moving a slider on the frame’s bridge changes the volume of liquid, adjusting the focus of the lens anywhere from distance to near.  Since the power is uniform throughout the lens, there are no visible lines or channels to look through and no need to tilt your head back when working at a computer or trying to read price tags on a grocery shelf.  However, in order to maintain clear vision, the power will have to be manually adjusted every time you look at a different distance.

Extra front lenses are available in either photochromic or a fixed tint (but no Polaroid) to swap out for outdoor use and they even have a special shuttle case to help you manage the lenses.

The Superfocus also suffers cosmetically. The double lens design makes them thick and, at least with the current technology, the lenses are round and are only available in two frame styles. You may turn heads when wearing a Superfocus frame but probably not because you’re looking “hot” in your new glasses.

The Superfocus system retails for about $800.  It  might be for you if you can’t tolerate progressive lenses or lined multifocal lenses, hate swapping back and forth between reading glasses and distance lenses and you can live with the geek chic look -OR- if you just think technology is neat.   But contrary to the marketing hype, don’t expect your vision to be like it was in your 30s.

The emPower lens by Pixel Optics shows more promise.  It got a lot of buzz when it was previewed at the Consumer Electronics Show in Vegas in January and the NY Times recently ran an article about it.  The lens design starts with a progressive lens with low reading power and adds a liquid crystal segment in the reading area of the lens that boosts the reading power by .75 diopters when a current is applied to the lens.  The lens is manually activated by touching the temple or it can be set to automatically boost the power when the head is tilted down.   By activating the extra near power only when needed,  there is less peripheral distortion when walking, driving or doing distance activities and a wider reading area than you would get in a standard progressive.

When released in April or May, the lenses will be available in 36 frames styles by Aspex and are estimated to retail for $1000-$1200.  The frame comes with a recharging station for the battery that must be recharged every 2-3 days.  While the frame/lens styles are definitely more stylish than the round Superfocus lenses, it appears that the lenses are taller than styles that are currently in vogue.  I suspect a deeper lens is necessary to have room for the full reading segment of the lens.  I’m all for frames with a larger reading area but, so far, fashion has trumped function for most of my patients.

Here’s the manufacturer’s video demo comparing the emPower lens to a regular progressive lens.  I would point out a few things to consider when looking at the demo.  The amount of distortion is greatly exaggerated by holding the lens away from the camera (eye).  Making the blue reading zone smaller on the left, also exaggerates the difference in distortion between the two lenses.  Also note the wider blue line to delineate the reading zone on the emPower lens.  I can’t be sure but I suspect that is to hide the transition area of the reading segment.  When the power boost is activated there will be a border like you have in a round bifocal segment with some “jump” of the image as it crosses into the reading zone. If look carefully you can see the image of the letters jump down a little as they enter the activated reading zone on the emPower lens while there is a smooth transition in the progressive lens.  That may or may not bother a patient but it appears to me that they are trying to camouflage that effect in the demo.

They also mention that the demo is against a “leading progressive” but don’t give the brand.  There is a huge difference in the amount and location of distortion between various lens designs and “leading” lenses are often the least expensive and have more distortion. For example, they say their comparison lens has “2.15 D of unwanted astigmatism.” A progressive lens that I frequently prescribe has 1.70 D of unwanted astigmatism and the new custom digital progressive lens designs should have even less.

While the emPower lenses do have less peripheral distortion and blur, the base lens is a progressive lens so there will be still be some blur when looking down and off to the sides.  But peripheral blur is not as big a deal as many people think. Your peripheral vision isn’t clear anyway.  It is designed to catch your attention so you can turn your head and look right at something to see it clearly. Try reading the digital clock on your microwave oven when you’re looking just a couple of inches to the right or left of it.  You can’t make it out because you only have “20/20” vision when you’re looking directly at something.  Most patients will quickly learn to turn their head to keep their central vision looking through the clear portion of the lens.

Blurring of the floor or steps is another complaint that emPower is supposed to address but, once again, most people adapt to this.  Unless you’re walking on an irregular surface, you typically look ahead, not down at your feet, when walking or taking the stairs.  The problem is that depth perception changes with any new prescription.  Patients may be tentative when walking around with new glasses so they look down at their feet for reassurance and now the floor is blurry!  After walking around in the new lenses, your depth perception adjusts and you stop looking at your feet.

The biggest shortcoming I see with the emPower lens is that it doesn’t address the most common complaint of people with higher reading prescriptions: the need to tilt your head back to see the computer screen or price tags on grocery shelves or even talking to someone 3-4 feet away. Those that work at computers all day long would still be better served by a dedicated pair of glasses designed for the computer.  If they can put the power boost in the distance portion of the lens, the design would be much more beneficial.

On paper, the emPower lens offers some optical advantages to people with high add powers, especially if they have trouble adapting to standard progressive lenses.  It’s hard to say how much of an improvement it offers over the new digitally customized progressive lens designs.  Pixel Optics will have a booth at the SECO conference that I am attending next week and, unfortunately, I am old enough to benefit from this lens!  Hopefully I will be able to demo the lens and report back on my impression of it in action.

At this point the emPower has technology worth watching but, for the premium price, I’m waiting for them to get the kinks worked out and prove that the technology and materials hold up under real world use.


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