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Posts tagged ‘no-line bifocals’

The Unavoidable Facts About Bifocals, Part 2

Treating Presbyopia (Eye condition which necessitates bifocals) with Contact Lenses: 

For years contact lens wearers considered the onset of presbyopia to be the time to make the forced switch fromcontacts to eyeglasses. Many are finding that this need not be the case. While contact lens manufacturers scramble to be the first to perfect and market a functional bifocal contact lens, the public has not embraced them in huge numbers. Meanwhile, more and more contact lens wearers are finding that they can treat their presbyopia with Monovision contacts.

Monovision doesn’t denote any special type of contact lens, but rather a special type of contact lens fitting. With monovision, the doctor fits you with a contact lens to correct one eye for distance vision while fitting your other eye with a contact lens for near vision. While this arrangement may sound unorthodox, monovision has been proven to be effective. Erie, Pennsylvania Optometrist James Piersol estimates, “Over eighty percent of my presbyopic patients who try monovision are ultimately successful with it. It normally takes one or two fittings to get the power balanced  properly, but once you do, the patient rarely can tell that each eye is performing a separate function.” Monovision is actually not as far-fetched as it sounds. Dr. Piersol explains, “The brain is always receiving two separate images from your eyes. It normally takes the two similar images and fuses them into one three-dimensional image. With monovision, the brain receives two very different images, one clear only at distance the other clear only at near. Since it can not fuse them into one picture the brain simply chooses between the two images based on the immediate task at hand, much like a director choosing between two camera angles”.

Skeptical? Try this experiment. Take a paper towel tube and with both eyes open look at your television screen. Now alternately close your right eye and then your left. The image from your dominant eye (the right for most people) will hardly move at all while the image from your non-dominant eye will jump noticeably. This is because as you sit there watching TV your brain is “choosing” the image from the dominant eye. If you were being fit for monovision the dominant eye would be fit for distance and the non-dominant eye would be fit for reading.

While monovision contacts do offer a proven and cost effective treatment for presbyopia, they also have a down side. Since your brain would be receiving only one image for distance and only one image for near, there is a resulting reduction in depth perception. This can be a critical problem for some people’s occupational requirements.

Treating Presbyopia with Surgery:

One reason for the growth in monovision contact lens fits is the rising interest in corrective eye surgery. While the public continues to warm to the idea of LASIK and other surgical procedures to correct distance vision, a medical correction is now emerging for near vision. It is called conductive keratoplasty, or CK. CK is a non-invasive procedure where radio waves are used to reshape the cornea in order to improve focus at near. The procedure is quick, relatively painless and a bit pricey. Because CK is done on only one eye the final result is very much like monovision without the contact lenses. That being the case, most people prefer to test their tolerance for monovision with contact lenses before moving on to the permanence and expense of CK.  Since presbyopia advances with age anyone considering CK needs to understand that additional procedures may be required every 3 to 5 years to keep up with their increasing presbyopia.

In the first 200 years after Ben Franklin invented the bifocal there were virtually no changes. Your father’s bifocals were very much like your great-great grandfather’s bifocals. By contrast, in the past 5 years over 176 differentProgressive Addition Lenses (PALs) have hit the market.  Each one is somehow superior to those that came before. The technology is improving exponentially.  Before too many years pass we’ll see doctors inject soft polymer plastic into the eye’s lens sac and thereby restore the lens’s flexibility. At that point it will be bye-bye bifocals.

To learn more about proper eye care, eye wear and Shawnee Optical, please visit our website at  www.shawneeoptical.com.  

The Unavoidable Facts About Bifocals, Part 1

On the list of unavoidable suffering, well behind death but only slightly ahead of  taxes, you’ll find bifocals.  For most of us, bifocals serve as a warning shot that middle age is hot on our heels. It’s a rite of passage that 95% of Americans over the age of 45 have experienced and in the next few years nearly 78 million baby boomers will join the Bifocal Club.

The eye condition is called presbyopia. The word is Greek for “old man’s eyes” but the roots of the condition actually start much earlier than the name implies. As teens, our eyes stop growing, but the lens in the eye continues to generate new cells. As a result, the lens gets progressively denser as time goes by. This increased density results in a stiffening of the lens. By the time we reach our mid forties the lens is so stiff that it can no longer make the transition from distance vision to near. Many of us will try to put off the inevitable by holding the newspaper further away or pushing the computer screen a little further back. Eventually, however, we find ourselves at the eye doctor’s office holding our first bifocal prescription.

Treating Presbyopia with Eyeglasses

Like our grandfathers, grandmothers, fathers and mothers, most of us will fight their emerging presbyopia with eyeglasses. Unlike our parents and grandparents however, many of us want nothing to do with unattractive bifocal lines. This cosmetic concern has made no-line bifocals, more accurately known as progressive addition lenses (PALs), the new clear-cut lenses of choice, but there’s more to PALs than just a pretty face.

“What consumers want,” notes Carol Norbeck, spokeswoman for the Vision Council of America, “is to see as if they never got old. That’s a tall order but progressive lenses are coming closer and closer to that goal”. Our parents’ traditional lined bifocals had two distinct prescription zones. You were either looking through the distance portion or through the reading segment, and when you passed from one zone to the other the image would suddenly change in size.  This is called image “pop”.  Functional? Yes, but it didn’t feel anything like normal vision. Today’s progressive lenses, by contrast, offer a gradual transition from distance to near prescription. The lens provides clear vision at  distance, near and points in-between with no image pop.

    In  PALs introduced in the 1980’s and 1990’s, the trade-off for the lineless design was a pair of  bothersome blur zones on either side of the transition corridor. Today, these older designs are called “hard progressives”. More recent lens designs, called “soft progressives” utilize advanced mathematical formulas and computer graphing to create a much more subtle visual transition from distance prescription to reading prescription. The blur zones have been greatly reduced and pushed to the periphery of the lens where they are safely out of the normal field of vision. The result is vision that feels very natural.

Shawnee Optical Consumer TipIn today’s optical marketplace hard PALs often sell along side the newer soft designs at surprisingly similar prices. Make sure you are being fit with a soft progressive lens. If your optician doesn’t know the difference find another optician.

To learn more about proper eye care, eye wear and Shawnee Optical, please visit our website at www.shawneeoptical.com.

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