Presbyopia

The lens, behind the iris, is normally adjusted by little muscles, which make it more curved or more flat, depending on how far away the object is that we’re looking at. But with age, the lens becomes more stiff and harder to adjust; and the little muscles become a bit weaker. So when we look at the print in our book, our lenses can’t adjust properly, and stay set for looking at the tree at the back fence, and the print appears blurry. That’s where bi-focals, whether glasses or contact lenses, are useful, because they correct for close-up vision while correcting differently for far vision, or not correcting it at all. Disadvantages of glasses
· They’re so easily misplaced
· They have to be modified periodically as we age and our vision changes
· If you work in a job where you change focus often, such as teaching, sales, performing arts or public speaking, glasses can be very inconvenient and annoying

One eye on the horizon

The idea of monovision is to correct one eye for the distance vision and the other for close-up vision. In cases where distance vision needs no correcting, just the near-vision eye would be corrected.

Eye doctors started doing this with contact lenses. They made one lens to correct distance vision and the other to correct near vision. When LASIK surgery came along in the late 1990s, some people chose to have one eye corrected for distance and the other for close-up work. This means that the two eyes don’t work together any more. As you can imagine, this takes some getting used to, but it can be done.

An upside down world

A related experiment was done in the late nineteenth century by George Stratton. He wore special glasses which turned everything upside down, so that he saw the floor where the ceiling would normally be, and vice versa, and all objects correspondingly upside down. He found that it only took about 3 days to adjust, so that things looked normal again. In other words, things didn’t look upside down, but looked just as they normally do. Then he took the glasses off and found everything looked upside down again. So again it took him a few days to re-learn and restore his normal vision.

Our brains can learn

With monovision, one eye is the distance eye and the other is the reading eye. We can learn to automatically use just one eye, the appropriate one for what is being focused on. The adjustment period is several weeks. Most people who have it done are pleased with the result. Now they can see near and far without any contacts or glasses. It’s a good idea to try monovision with contact lenses first, to see how well you can adjust to it, and many people do this. Disadvantages of monovision
· A slight loss of depth of perception
· A slight loss of peripheral vision
· If you need to see extra clearly at certain times, such as for night driving or long sessions with reading or computer work, you might want some reading glasses for those occasions, but will not need them for routine tasks

Advantages of monovision
· You’ll need no glasses or contact lenses most of the time, perhaps ever
· You can legally drive without any vision correction
· The cost is lower than that of LASIK or other laser procedures
· It can be undone

If you have it done and decide you don’t like it, you can have it undone, and your “near” eye corrected for distance. Then your 2 eyes will be working together again but you’ll need to wear reading glasses.

If you wear bifocals or reading glasses, you might like to consider the option of dispensing with them and instead, using your brain’s adaptive power to learn monovision. Some LASIK centers give little information about monovision. Some take time with you to explain how it works and answer your questions.

If you have it done and then change your mind about it, some will follow up with you and correct your near eye for distance vision at no charge, so that you can revert to using your reading glasses.

www.levinsoneyeclinic.com For more information about presbyopia correction with monovision, feel free to contact a LASIK surgeon in your area, such as Dr. Levinson of Denver, Colorado.