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Narrow-Angle Glaucoma
Acute
narrow-angle glaucoma occurs
suddenly, when the colored
portion of your eye (iris)
is pushed or pulled forward.
This causes blockage of the
filtration angle of the eye,
where the trabecular
meshwork allows outflow of
fluids.
When internal eye structures
are blocked in this way,
your eye's internal pressure
(intraocular pressure) may
spike and possibly damage
the optic nerve that
transmits images from the
eye to the brain.
Acute angle-closure
(closed-angle or narrow
angle) glaucoma produces
symptoms such as eye pain,
headaches, halos around
lights, dilated pupils,
vision loss, red eyes,
nausea and vomiting.
These signs may last for
hours or until the IOP is
reduced. With each narrow
angle glaucoma attack, part
of your peripheral field of
vision may be lost.
Acute angle-closure glaucoma
is a medical emergency. If
the high pressure is not
reduced within hours, it can
damage vision permanently.
Anyone who experiences these
symptoms should contact an
ophthalmologist immediately
or go to a hospital
emergency room.
Some chronic forms of
narrow-angle glaucoma,
however, can progress very
slowly to cause eye damage
without any obvious symptoms
or pain in early stages.
Causes of Narrow-Angle
Glaucoma
Causes of the abnormal
positioning of the iris in
narrow-angle glaucoma
include:
-
Pupillary block.
Eye fluids known as the
aqueous humor are
produced in the ciliary
body, which is located
behind the iris.
Normally, the aqueous
flows easily through the
pupil into the front or
anterior chamber of the
eye. But if the back of
the iris adheres to the
lens inside the eye,
this pupillary channel
becomes blocked. Then
fluid backs up behind
the iris, pushing the
iris forward until it
closes the drainage
angle in the anterior
chamber.
-
Iris plateau. In
this condition, the iris
is attached to the
ciliary body too close
to the trabecular
meshwork, where drainage
occurs. When the pupil
dilates, the peripheral
iris tissue bunches up
in the filtration angle
and can cover up the
drainage meshwork,
causing IOP to rise
quickly. This type of
narrow-angle glaucoma
attack can occur in
conditions when the
pupil dilates in dim
lighting or when eye
drops are used to
intentionally enlarge
the pupil during an eye
exam.
-
Hyperopia. People
who are farsighted are
more likely to have
shallow anterior
chambers and narrow
angles, increasing their
risk for angle-closure
glaucoma from pupil
dilation or aging
changes in the eye.
-
Tumors, eye
disease and other
causes. A tumor
behind the iris,
swelling associated with
inflammation of the
ciliary body
(intermediate uveitis)
and alteration of the
shape of the eye after
retinal detachment
surgery can also cause
angle-closure glaucoma.
Risk Factors for
Narrow-Angle Glaucoma
In addition to hyperopia,
risk factors for acute
angle-closure glaucoma
include:
-
Age. As we grow older,
the lens inside our eyes
gets larger, increasing
the risk for pupil
block. Also, the
anterior chamber tends
to become increasingly
shallow, and the
drainage angle may
narrow as we age.
-
Race. Asians and
Eskimos, who have
anatomically narrower
anterior chamber angles
than whites, have a
higher incidence of
angle-closure glaucoma.
-
Sex. Among Caucasians,
angle-closure glaucoma
occurs three times more
frequently in women than
in men. Among
African-Americans, men
and women appear to be
affected equally.
Treatment of Narrow-Angle
Glaucoma
The goal of treatment is to
reduce intraocular pressure
as soon as possible. This
can be done with systemic
medications taken orally or
sometimes given
intravenously. Topical
glaucoma eye drops are also
often used to treat
narrow-angle glaucoma.
Frequently, laser and/or
nonlaser glaucoma surgery
may be required to reduce
the IOP.
Remember that acute
angle-closure glaucoma may
be triggered by anything
dilating the pupil,
resulting in the iris
blocking the angles. Dim
lighting, eye drops
administered by your eye
care practitioner during an
eye examination, or certain
medications such as
antihistamine/decongestant
drops or cold medications
may cause an acute
angle-closure glaucoma
attack.
In acute forms of glaucoma,
optic nerve damage and
vision loss will occur
within hours if the angles
of the interior eye
structure are not opened to
drain fluid and lower IOP
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