Monovision is an option for some people who are considering Lasik surgery; Monovision refers to the use of one eye for distance viewing and the other eye near vision. This procedure has been used with a good degree of success for over 20 years; the Lasik surgeon will ‘correct your strongest eye for distance vision and your weakest eye for near vision.
A major factor in the Lasik surgeon’s decision to recommend the Monovision option is your age. At approximately age 40 your eyes’ ability to change focus from far to near starts to deteriorate; this condition, the loss of focusing ability, is called presbyopia.
Performing Lasik on both eyes of a person over 40, to allow them excellent far vision in both eyes will, in most cases, mean that the patient with some degree of presbyopia will need reading glasses for clear close vision.
This procedure may seem, at first, like it will create a very blurry, confused vision problem that causes you to go through life with one eye open and one eye closed at all times but it’s not like that at all. The vision part of our brain tends to compensate for Monovision by ‘filtering out’ the image from the eye that is not in clear focus. In other words, if your left eye is your distance eye and your right eye is your near eye, when you are sitting reading a book, your brain will ignore the unfocused image from your left eye.
Two important things to remember are:
The ability to change focus only goes from far to near, i.e. if your eye is corrected for near vision it cannot change focus to clearly see distant objects where, conversely, if your eye is correct to see clearly at a distance it CAN, if presbyopia is not a factor, focus from far to near.
The brain adjusts to ignore the out-of-focus eye and should fully adjust to Monovision within 6-8 weeks.
Monovision considerations. Most Lasik surgeons will not recommend Monovision if you are under the age of 35 because, at that age your eye should still be able to shift focus and should be able to do that for a number of years. Another factor is that, by the time you might benefit from Monovision, there might be a much better treatment for presbyopia.
The most serious consideration when considering Monovision is the resulting loss of depth perception. Driving a car with one eye closed can cause severe anxiety until and unless you are accustomed to driving with just one eye — that is, in effect, the effect of Monovision. Your brain will be ignoring one eye or the other, as it is being trained to do.
What to do? It would appear that the best course of action for someone who is unsure about or scared of the Monovision option would be to get both eyes corrected for the best possible distance vision and then plan to use reading glasses for up-close work. If, however, you want to try Monovision to see if it works for you and then decide you don’t like it, there is a Lasik procedure that can enhance the near eye so that it matches the far eye which, again, leaves you with the reading glasses option.
Glasses in your future? If you do not have presbyopia now you probably will as you and your eyes get older; if you have it now it will get worse. Lasik distance vision correction in both eyes will not, except in a few cases, prevent the patient from ever wearing glasses. The benefit of having the Monovision procedure is that you are unlikely to have a need for glasses for up close work or reading as you get older.
The contact lens option. If you are not completely against contact lenses and want a non-surgical option, contact lenses can be prescribed for you by your optometrist that will allow you to try Monovision. Just like with the Lasik option, it will take some time to get your brain to adjust to Monovision and, additionally, you will need to adjust to using contacts if you have never tried them.
Results. A survey of Lasik patients with the Monovision correction has determined that approximately 85% of the patients liked Monovision enough to keep it for the long term. The other 15% were uncomfortable enough with the procedure or were unable to adjust to it and decided to give it up in favor of having the near eye adjusted to match the far eye.
Still another option. If you choose the Lasik Monovision option and find certain activities to be problematic, you can get a contact lens fitted into one eye (usually the near eye) to have it match the other eye.