PIE more favorable than Multifocal Contacts or Progressives

I can remember the day a young single woman in her forties told me why she hated her readers so much. She said her dates considered her to be in her thirties till her readers came up to check out the menu. Since then and after speaking with many youthful looking individuals, I realized that wearing readers is a true nuisance. As we stress on physical activity and good diets, we are able to keep our bodies younger for a longer amount of time but the eyes seem to be from a different world. People also hate to carry around the readers or hang them from their necks. If they forget them on a trip or the glasses break, it can affect the working day especially for a pilot.

What have the other options been for these people till now?

Let’s consider multifocal glasses termed bifocal, trifocal and progressives. Bifocals have two foci distance and near, trifocal has an additional for near while progressives have multiple foci. The first deficiency like of any eye wear is the limitation of peripheral visual field. This can vary from a nuisance of turning your head to see in periphery to difficulty performing critical tasks like driving. During rainfall or in foggy conditions these can create a real problem and you may as well forget about water activities.

Are progressives really safe? This might seem like a joke but there are people with progressives who get so tired adjusting their head and shoulders to see better that they develop neck and shoulder problems that can require physical rehabilitation. A few might even become susceptible to depression.

Contact lenses can be used to create monovision. We have discussed that elsewhere, so now we can restrict our discussion to multifocal contact lenses. These are soft contact lenses which have alternating rings for distance and near zones. In the center is a primary viewing zone. This is usually for distance (called a center-distance design), but in some model’s center-near designs also are available. These latter are more often used in non-dominant eyes and with large pupils.

The near add power, this can be low, mid or high power. They differ than PIE as they are refractive lenses and not diffractive lenses. Refractive PIE implants have been abandoned.

Why do multifocal contact lenses do not work? With each blink the lenses move. We know even a few microns movement of pie can affect vision. Now imagine constant movements with every blink, and a different amount of movement each time. That means a different version of the world every few seconds. Neuroadaptaion in such circumstances is very difficult.  Less than 30% of people can adapt. That may seem like a big number but remember very few people can tolerate contact lenses in that age group. Brain reacts to this by “Killing me slowly with your winks”.

Like any contact lenses, they are difficult to wear especially with dry eyes, hand tremors, small eyes and the like. There is always the chance of scratching or an eye infection.

PIE eliminates the movement aspect and is designed as a diffractive lens which continues to improve with time. Once implanted in sterile conditions, it is immune from infections. It does not cause dry eyes and works in even in amnesiacs who forget where they have placed their glasses or contact lenses.

About the Author Rajesh Khanna, MD

Los Angeles Lasik Surgeon Rajesh Khanna MD is a recognized pioneer in Presbyopic Implants for correction of aging eyes. He has popularized Cornea Cross Linking and Intacs forKeratoconus. He is an Expert Cataract, Pterygium Eye Surgeon, A Cornea Specialist he performs Laser Corneal Transplants, DMEK, DSEK and DALK. Rajesh Khanna MD is a well known medical writer. He has published the bestseller "The miracle of Pi in Eye".He is also a columnist for the newspaper Acorn. Dr.Khanna also hosts "Medical Magic". In his spare time he hikes with his family and German Shepard or does yoga. He also plays field hockey and loves swimming.

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