What is Monovision?
The answer to 'what is monovision', for those people already requiring bifocals, most of whom are over the age of 45, will generally be to use reading glasses. Usually drugstore readers will suffice. But some people won’t see the advantage of trading distance glasses for reading glasses.
A technique which I have been using for over 30 years is called Monovision. Initially I created monovision for presbyopic patients with contact lenses. I then advanced to performing monovision cataract surgery and most recently with refractive surgery.
In monovision one eye (usually the dominant eye) is corrected for distance vision and the other eye (the non-dominant eye) is corrected for near vision.
In contact lens monovision, the contact lens on the dominant eye corrects your distance vision and the contact lens on the non-dominant eye corrects your near vision. Although the lens for distance vision is usually worn on the dominant eye, about one in three people can successfully be corrected the other way around.
In order for the human brain to adapt to monovision it is critical to keep both eyes open for all vision functions. Any time one eye is closed the brain’s adaptation process will be slowed down and if closing one eye becomes a habit the person runs the risk that adaptation to monovision will fail. If you succumb to the temptation to close one eye, the eye that is corrected for distance vision will be slightly blurred up close and the eye that is corrected for near vision will be slightly blurred when looking at distant objects. But with both eyes open, the typical result is clear and comfortable vision at all distances. Most people adjust well to monovision, and eventually don't even notice which eye is their "distance eye" and which is their "near eye." It makes a great deal of sense to perform a brief, in-office, contact lens trial to be sure that there are no side effects, such as dizziness or vertigo. In very rare patients those symptoms will occur and thus may preclude performing monovision laser vision correction. In those cases a longer trial encompassing a couple of days to a couple of weeks during which time the patient can experience monovision during all normal activities in order to decide whether (s)he would choose monovision as a permanent solution.
With monovision rare people will find that it reduces the clarity of their distance vision, making distant objects appear slightly blurred. Others may find that it does not provide adequate near vision to give them the freedom from reading glasses they were hoping for. Still others may notice a decrease in depth perception. Therefore monovision is not a good idea for pilots, long-distance truck drivers or professional athletes.
The term "monovision" is somewhat misleading because the two eyes are always working together as a team to see clearly at all distances. A more meaningful term would be "omnivision"; however the former word has been in such general use for so many years, it would be difficult to adopt a new term.
The concept of monovision can also be created in surgery for presbyopia. Monovision correction can be accomplished with LASIK, Epi-LASIK and PRK and in my practice I do so very frequently.
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