What Is Astigmatism?
Astigmatism is a common vision problem caused by an error in the
shape of the cornea. With astigmatism, the lens of the eye or the cornea, which
is the front surface of the eye, has an irregular curve. This can change the
way light passes, or refracts, to your retina. This causes blurry, fuzzy, or
distorted vision. Farsightedness and nearsightedness are two other types of problems
with the way light passes to your retina. Farsightedness is called hyperopia. Nearsightedness
is called myopia.
What Are the Types of Astigmatism?
The two main types of astigmatism are corneal and lenticular. A
corneal astigmatism happens when your cornea is misshapen. A lenticular
astigmatism happens when your lens is misshapen.
What Causes Astigmatism?
It’s not known what causes astigmatism, but genetics is a big
factor. It’s often present at birth, but it may develop later in life. It may
also occur as a result of an injury to the eye or after eye surgery.
Astigmatism often occurs with nearsightedness or farsightedness.
Who Is at Risk for Astigmatism?
Astigmatism can occur in children and adults. Your risk of
developing astigmatism may be higher if you have any of the following:
- a family history of astigmatism or other eye
disorders, such as a degeneration of the cornea called keratoconus
- scarring or thinning of your cornea
- excessive nearsightedness, which creates blurry
vision at a distance
- excessive farsightedness, which creates blurry
- a history of certain types of eye surgery, such
as cataract surgery (surgical removal of a clouded lens)
What Are the Symptoms of Astigmatism?
The symptoms of astigmatism may differ in each person. Some
people don’t have any symptoms at all. The symptoms of astigmatism include:
- blurry, distorted, or fuzzy vision at all
distances (close-up and far away)
- difficulty seeing at night
- eye irritation
See a doctor if you have symptoms of astigmatism. Some symptoms
may also be due to other health or vision problems.
How Is Astigmatism Diagnosed?
An optometrist or ophthalmologist diagnoses astigmatism through a
comprehensive eye examination. An optometrist is a doctor who diagnoses vision
problems and eye diseases. An ophthalmologist is a doctor who provides medical
and surgical treatment of vision problems and eye diseases. There are several
tests optometrists and ophthalmologists may use during your eye examination to
Visual Acuity Assessment Test
During a visual acuity assessment test, your doctor will ask you
to read letters from a chart at a specific distance to determine how well you
can see the letters.
A refraction test uses a machine called an optical refractor. The
machine has multiple corrective glass lenses of different strengths. Your doctor
will ask you to read a chart while looking through lenses that are different
strengths on the optical refractor. They’ll eventually find a lens that
appropriately corrects your vision.
Keratometry is a way for your doctor to measure the curvature of
your cornea. They will do this by looking at your eye through a keratometer.
What Are the Treatments for Astigmatism?
Mild cases of astigmatism may not require treatment. Your doctor may
treat astigmatism that causes vision problems by using one of the following
Corrective eyeglasses and contact lenses prescribed by a doctor
are the most common and least invasive treatments for astigmatism.
Orthokeratology (Ortho-K) is a treatment that uses rigid contact
lenses to temporarily correct the irregular curvature of your cornea. You’ll
wear rigid contact lenses for limited periods of time. You may wear them during
sleep and then remove them during the day. Some people have clear vision during
the day without corrective lenses when undergoing Ortho-K. The benefits of
Ortho-K are only present when using it. Your vision will return to its previous
state after stopping Ortho-K.
Your doctor may recommend refractive surgery if you have a severe
case. This type of surgery involves using lasers or small knives to reshape
your cornea. This will permanently correct your astigmatism. The three common
surgeries for astigmatism are laser in situ keratomileusis (LASIK),
photorefractive keratectomy (PRK), and radial keratotomy (RK). All surgeries
carry some risks. Talk to your doctor about the risks and benefits before
getting surgery for astigmatism.
What Are the Complications Associated with
A lazy eye can occur if astigmatism in one eye isn’t corrected.
Lazy eye is also called amblyopia.
What Is the Long-Term Outlook?
Corrective lenses or surgery can usually restore your vision to
normal. There’s no known way to prevent astigmatism from developing.