Monovision is a fairly common medical technique ophthalmologists use to correct the effects of presbyopia. Presbyopia is a fairly naturally occurring phenomenon that comes with age, specifically the gradual loss of the eye's ability to change focus for close-up tasks like reading. The most common accepted theory about presbyopia (and thus the possible need for monovision with Lasik or other means) is that the aging eye starts to lose elasticity in its crystalline lens, or possibly changes in the curvature of the lens.

Monovision and Lasik

What the eye professional will do is to correct the vision of the presbyopic patient by adjusting one eye for near viewing and one for distance viewing. This used to be done primarily with contact lenses; the doctor would fit one eye with a lens to correct the near vision, and the other eye with a different prescription to correct the far vision.

The idea is the same with Lasik - one eye is operated on to correct the farsightedness, and one the nearsightedness. In other words, the goal is to operate for vision worse than 20/20.

The problem with this is that because each eye is corrected for different distances, the two eyes cannot work in tandem anymore, resulting in poor quality of vision and a depth perception decrease. Brightness helps this resulting monovision by shrinking the iris. However, it's worse and more noticeable in environments with low light and in instances when very sharp vision is required, such as reading small print for long periods of time or night driving.

Also, there is the possibility that - because it's not always clear how slow or fast the muscles of each eye will grow or change with age - Lasik surgery for other eye symptoms could result in the inadvertent result of monovision.

Considerations for Those With Monovision

If you are considering monovision through Lasik surgery, it is really important to talk to two or three well-regarded ophthalmologists to have a thorough check up. One needs to know how much his or her presbyopia might or might not increase in the future, and whether his or her eye(s) can tolerate a second or third procedure to correct any problems later.

Often times patients are unsure whether they would prefer to have their eyes surgically corrected so they have to work in tandem (thus monovision) or just have both eyes corrected to see equally. There are costs and benefits with both; it really depends on your doctor's assessment of your eyes and your personal habits.