A cataract is when the normally clear
crystalline lens within the eye becomes cloudy. Cataracts
are normally associated with aging, but may occur at birth
or be caused by illness or trauma to the eyes. Cataracts are the
leading cause of correctible blindness in the world,
affecting millions each year.
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No symptoms
Cataracts normally form very slowly,
so their effects may not be noticed. It is very possible
that someone with a cataract believes that vision is
fine, or vision difficulties are just "old age", but the
vision limitation is actually caused by a cataract. Many
who have had cataract surgery are surprised about how
much their vision had been affected by the cataract.
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Frequent Prescription Changes
As the cataract forms and progress
it can change the shape of the natural crystalline lens
and thereby change focal power. This can lead to
frequent changes in eyeglass and contact lens
prescription and moving astigmatism.
In an attempt to regain vision lost
by cataracts, patients sometimes try stronger and
stronger glasses, however glasses do not resolve the
vision limitations of a cataract.
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Vision 20/40
or worse with glasses
A common sign of cataracts is the
inability to correct vision with glasses
to 20/40 or better. There are other maladies that can
present this same symptom, but the vast majority of
seniors who are no longer able to see enough to pass a
driver's license test have cataracts.
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Unclear
vision near and far
As the natural crystalline lens
within the eye becomes cloudy from a cataract, light
that would normally pass through the lens may be blocked
or scattered rather than focused when reaching the
retina. This light blocking or scattering of light
affects vision quality whether the light is focused for
near objects or distant objects. There are other
maladies that can present this same symptom, but many
seniors who have poor vision at distance and near even
with glasses, reading glasses, and/or bifocals will have
cataracts.
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Poor night vision, halos, starbursts
As the natural crystalline lens
within the eye becomes cloudy from a cataract, light
that would normally pass through the lens may be blocked
or scattered rather than focused when reaching the
retina. This light scatter can present as halos or
starbursts around light sources at night.
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Hazy vision
As the natural crystalline lens
within the eye becomes cloudy from a cataract, light
that would normally pass through the lens and reach the
retina to be seen is blocked or altered. This can
present as hazy vision. Because cataracts may affect
only a portion of a person's field of vision, there may
be a hazy spot, while the remaining field of vision is
clearer.
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Glare
As the natural crystalline lens
within the eye becomes cloudy from a cataract, light
that would normally pass through the lens may be scattered rather than focused when reaching the
retina. This light scatter can present as glare, causing a
white-out appearance.
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Ghost images, double, or multiple images
Cataracts tend to start small and
then grow within the natural crystalline lens of the
eye. As the cataract grows, it can change the shape of
the lens. This shape change may be irregular. An
irregular shaped lens can cause multiple images or a
faint ghost image next to the main image. Ghosting may
decrease as the cataract progresses and becomes more
universal to the lens.
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Better near vision,
worse distance vision
As cataracts progress, they change
the shape of the natural crystalline lens. This change
in shape can make a person's vision more myopic
(nearsighted, shortsighted). Being myopic means that you
can see near objects better than distant objects. This
is sometimes called second sight.
As
cataracts make a person more myopic, reading glasses
become less necessary, however distance vision becomes
worse and distance glasses may be required for certain
activities, such as driving.
