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Accommodation
(the ability of
the eye to focus at various distances)
The normal lens inside the human eye has
the ability to change shape, and hence its power. This allows
it to focus light on the retina whether the light is coming from
far away (the lens becomes thin), or from a near object (the
lens becomes thick)
illustration from Answers.com
To focus on a near object,
like when reading a book or seeing something closely, the lens
inside the eye increases its curvature, so that the power of the
eye is increased and the image comes to a good focus on the
retina or the sensitive film in the back of our eyes. This
process is called accommodation, and is strongest in early
life. However, the lens’s ability to accommodate declines with
time because of a natural loss of its elasticity. Presbyopia is
the result of these changes and is noticed when we reach our
40’s and 50’s. This is why reading glasses become necessary –
they provide the extra focusing power required to see near.
In recent years, we started
to have several options for correcting this focusing difficulty
by laser treatment or by the implantation of a
multifocal lenses
inside the eye after removing the naturally occurring lens. This
is an excellent alternative for people who have
cataract and
need it to be removed. After removing the opaque lens
(cataract), we now have the option of implanting an artificial
multifocal lens (several excellent options are available in
recent years), and thus restoring the ability of focusing the
eye on far, intermediate and near objects.
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