Monovision is a form of vision correction treatment for presbyopia. One eye is fully corrected for distance vision, while the other is under-corrected. This will leave the under-corrected eye with a mildly myopic prescription (nearsighted) for near vision. This vision procedure can be done with either LASIK or PRK laser eye surgery.
The distance vision in this under-corrected eye is blurrier, but the near vision is sharper. This small amount of myopia allows a patient with presbyopia (over 40 years old) to see clearly up close, and therefore can avoid or reduce the need for reading glasses.
This situation is a compromise. It does not eliminate presbyopia, but improves it. Distance vision is not perfect, but good. Near vision is not perfect, but good enough to function. Monovision will allow someone with presbyopia to read a label, tell the time on his or her watch, shave in the mirror, or read a menu in the restaurant. Very fine detailed near tasks will still require reading glasses, as well as prolonged near tasks, such as reading a book for several hours.
Eventually with age, almost everybody will still require reading glasses for up close tasks. It may take two to three weeks for the brain to adjust to monovision. Some people love it; others cannot tolerate the imbalance between the two eyes.
Disadvantages of Monovision
- Decreased depth perception, particularly for sports.
- Reading very fine print or reading for long periods of time will still require reading glasses.
- Driving long distances at night may be more difficult. (This can be overcome by wearing corrective glasses while driving.)