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Toric Contact Lenses for
Astigmatism
Toric contact lenses are
made from the same materials
as regular ("spherical")
contact lenses, so they can
be either soft or RGP. The
difference is in the design
of the lens.
Toric lenses have two powers
in them, created with
curvatures at different
angles (one for astigmatism,
the other for either myopia
or hyperopia). There's also
a mechanism to keep the
contact lens relatively
stable on the eye when you
blink or look around. To
provide crisp vision, toric
contact lenses cannot rotate
on your eye.
matism, between zero and
1.00 diopter (either +1.00
or -1.00), you may be able
to wear a regular spherical
RGP or even a spherical soft
lens.
How can you see well if
there is no power for
astigmatism? With RGPs, the
lenses' rigidity can help
mask a need for an
astigmatic correction,
because your cornea will to
some degree conform to the
shape of the lens. With soft
contact lenses, some eye
care professionals choose to
fit you with a higher
powered spherical soft lens
to mask a small astigmatic
correction. The results of
this technique vary from one
patient to the next, which
is why the fitting process
may take some trial and
error by both the doctor and
the patient.
Also, some lenses are
available that may reduce
the spherical aberration of
your eye (that exists along
with the myopia or
hyperopia, and astigmatism).
This type of lens may help
some people who have
astigmatism to see better
without the necessity of a
toric lens.
Spherical lenses have the
same power all around the
lens, so it doesn't matter
if the lens rotates on your
eye. Toric lenses have two
different powers in the
lens, so they must remain in
position for best visual
acuity. Some toric lenses
are heavier (ballasted) at
the bottom to keep from
rotating.
A small percentage of
patients will find that they
prefer RGPs over soft
contacts. Because rigid
lenses retain their shape on
the cornea better than soft
lenses, they tend to provide
crisper vision to people who
have astigmatism. This
degree of difference in
crispness is not noticeable
for most contact lens
wearers, but if you're
particularly fussy about
your vision, you may
appreciate it.
Many brands of soft toric
lenses are available today,
so your eyecare practitioner
can choose the brand with
the best characteristics for
your particular eyes. Torics
are available as frequent
replacement, disposable and
even daily disposable
lenses. Toric silicone
hydrogel lenses for 30-day
wear are also available.
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