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Advances in Eyeglass Lenses
Perhaps
another reason for the
enduring popularity of
eyeglasses can be found in
new lens designs, which help
eyes to see better or appear
more attractive even when
stronger prescriptions are
needed. Because these new
types of lenses are thinner,
the old days of thick, Coke
bottle style glasses have
virtually disappeared.
Among the most popular types
of lenses prescribed today
are:
Aspheric lenses, which are
not perfectly rounded on the
surface, recently have been
designed as a way to correct
for small distortions in
vision that can be
associated with more
traditional lenses. These
types of designs also make
lenses thinner and lighter.
High index materials also
are associated with thinner,
lighter lenses, because of
the more efficient way this
special plastic refracts
light to help you achieve
focus. Because less plastic
is needed with high index
materials, lens thickness is
reduced.
Wavefront technology lenses
are fabricated based on very
precise measurements of the
way light travels through
your eye, which helps
sharpen visual clarity.
Polycarbonate is a type of
shatter-resistant plastic,
considered a major advance
over earlier plastics used
in lens fabrication.
Polycarbonate lenses also
are lighter and thinner than
basic plastic lenses,
because they have a higher
index. Because polycarbonate
lenses are tough and
scratch-resistant, they are
highly recommended for
children and active adults.
Photochromic lenses have
chemical coatings or special
internal changes allowing
them to quickly darken in
bright conditions, and
quickly return to normal in
ordinary indoor lighting or
at night.
Polarized lenses diminish
glare from flat, reflective
surfaces (like water) and
also reduce eye fatigue.
Anti-reflective coatings are
among the most popular
add-ons for lenses. They can
dramatically improve the
look and comfort of your
glasses by minimizing
reflected light that might
otherwise appear on the
lens, which also has the
added benefit of reducing
glare and thus easing eye
fatigue.
Other lens coatings include
scratch-resistant,
ultraviolet treatment, and
mirror coatings.
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