Monovision correction is a technique devised to help people who lose the ability to read when they hit the forties. It essentially means making or keeping one eye for distance and setting the other eye for near. If a person has 20/20 for distance in both eyes, than the dominant eye is left alone whereas the non dominant eye is allowed to become the reading eye. If both the eyes are nearsighted than the non dominant eye is undercorrected to leave residual power for reading. If both eyes were farsighted the non dominant eye is overcorrected to achieve ability to read. We can determine dominance by asking a patient to look faraway object through a hole and bring it to his/her eye quickly. That eye is the dominant eye. You can also figure about your dominant eye by recollecting the eye you use through peepholes, for shooting, for the viewfinders in old fashioned cameras. A word of caution. Some people may prefer to have their nondominant eye made the distance eye. Hence it behooves the eye doctor to check all options to ensure a person is given the best chance to feel comfortable.
How does one achieve Mono-vision?
Monovision cannot be achieved by simple glasses. A person cannot adapt to glasses If the difference in the power of glasses of two eyes is more than 1.5 Dioptres. The contrast in image size is too much for the brain to fuse.Thats where contact lens proved to be a boon in the last century. Optometrists fitted contact lenses in their eye centers. As patient aged from 45 to 50 and than to 55 and beyond they adjusted the prescriptions to allow for reading. This gradual but frequent change allowed the brain to adapt to progressive differences in image sizes generated from the two eyes. Cataract Surgery could also create the same situation though more suddenly. Many cataract surgeons offered the option of monovision after cataract surgery. This yielded to minimono/blend vision with accommodative crystalens. Today monovision can be achieved more permanently by lasik eye surgery. Of course you should not do lasik if you are suffering from cataracts in your eyes.
Some people may have natural difference in the power of their eyes. One eye may be 20/20 other may be nearsighted. This gives them a natural monovision ability.
Is monovision Lasik right for me?
If you have already done monovision with contact lenses than it is easy to predict that you will be happy with lasik monovision. If you have not,the best way to determine that would be to have a lasik eye surgeon test and advise you. Because if it does not work out he should be willing to reverse the monovision free of charge. Yes lasik can be reversed. In our practice we do a simulated exam including walking with the patient, having them sit in their car. Sometimes we imitate post op result with trial contact lenses and let patients do a trial run for a few days. WIth these techniques are rate of reversal of mono vision lasik has been close to zero.
Advantages of Monovision.
1. Freedom from glasses
Disadvantages of monovision.
1. Loss of binocularity or depth of perception.
2. Intermediate zone like smart phone, laptops could be difficult
Disadvantages of mono vision with contact lenses.
1. Contact lenses have to be shown in various studies to be at least seven time more dangerous than Lasik eye surgery.
2. Contact lenses cause foreign body sensation, irritation and dry eyes.
3. People with dry eyes may not be able to tolerate them.
4. Patients with tremors, joint problems or fear may find it difficult to insert and remove them.
For people above 50 desiring a permanent solution which retains depth of perception we offer Pi in Eye.
I have had mono vision Lasik but not happy with it
Experienced lasik eye surgeons can reverse this by lasik or superlasik. Pi in eye may even be a better option.