Monovision
Monovision is the practice of seeing
with different visual acuities in the right and left eyes.
Because the brain is separated into right and left
hemispheres, it is entirely possible to exercise independent
acuities (focus) for each eye and achieve a normal vision
practice. This
is most often applied to a person who has
presbyopia, the
inability to focus on near objects after being corrected for
distance. This
occurs over time when a nearsighted person is constantly
focusing on near objects with their corrective lenses
(glasses or contacts).
The natural lens of the eye is being overworked,
thinning itself for distance then fattening to a convex
shape for near.
This constant cycle produces hysteresis in the natural lens,
causing it to stiffen and lose its ability to change shape.
Although unfortunate to lose binocular acuity, this
can be overcome with the practice of monovision.
Ways for nearsighted people to avoid
presbyopia is by slipping their distance glasses off when
reading, or if using contacts, wear them for only a minimal
time of up to eight hours. If doing extended close-up
work, it's a good idea to take contacts out for that
period, and then put them back in later.