Vision
is a complex experience involving sharp acuity for near and distance,
color vision and perception, motion detection, flicker
fusion, contrast awareness,
depth perception, peripheral vision and many other phenomena. The
system requires a well functioning eye, a connection with the visual
cortex of the brain and the training and experience
to understand what you a connection
with the visual cortex of the brain and the training and experience to
understand what you have seen. It also requires a feedback nerve loop that
continuously
tracks any objects that you are interested in. Following
are a few examples:
Snellen
Visual Acuity - "20/20" vision
refers to the size of a letter projected
onto a chart that a person with "average" or "normal" vision
can see at 20 feet. Someone with 20/40 vision
needs to go to 20 feet to see what the "normal" person
can see at 40 feet and the person with 20/200
vision needs to go to 20 feet to see what
the "normal" person can see at
200 feet. The same information is often documented
in meters (6/6 =20/20 ) or even numerically
as 1.0 . Most states require 20/40 vision
or better in at least one eye to get a driver's
license without a restriction for glasses
or contact lenses.
Monocular
Vision - When you get to be 40 + you
often lose your ability to read (presbyopia)
up close. At Natural Vision (tm) we can use
this to your advantage by correcting one eye
for near and the other for distance. One of
the best ways to define monovision, in the
context of contemplating refractive surgery,
is that you can aim to have each eye corrected
to a natural focus at any distance you choose. As
a rule, we don't suggest monovision if you
are under the age of 35 for two reasons. The
first being that it will be a number of years
before there will be any benefit from it and
second being that it is very possible that
there will be a better (or at least as good)
surgical way to help correct the effects of
presbyopia by the time it is a problem for
you. We also would most likely recommend against
it at any age for people who may need to see
better than average for certain tasks. Some
examples of this type of person might include
airline pilots, race car drivers, someone who
drives for a living (especially at night),
and avid tennis or baseball players (especially
for playing at night). In our experience, most
people over the age of 40 to 45 who try monovision
and take a few months to become accustomed
to it, like it and find it very useful.