Astigmatism: Causes, Treatment And More

Astigmatism is a refractive error caused by an abnormally shaped cornea. It is one of the most common vision problems, affecting about 1 in 3 people in the United States.

Because of its prevalence, many patients wonder if astigmatism can be corrected — or if astigmatism can go away. Unfortunately, astigmatism can not be corrected on its own but there are many safe and reliable options available to help patients treat the condition.

Astigmatism is when the cornea of the eye is unevenly curved. This curvature alters the way light passes through and can cause blurry, fuzzy, or distorted vision.

To paint a more visual picture, a healthy eye has a round shape similar to a baseball. An eye with astigmatism has a curved shape that resembles a football. This makes it more difficult for light to pass through and causes vision problems at both close and long distances.

There are two common types of astigmatism: corneal and lenticular. Corneal astigmatism occurs because of an irregularity in the cornea. Lenticular astigmatism is the result of distortions in the lens.

Another way to differentiate types of astigmatism is regular vs. irregular. Regular (horizontal) astigmatism occurs when the eye is wider than it is tall. Irregular (vertical) astigmatism occurs when the eye is taller than it is wide.

Astigmatism occurs because of the abnormal shape of a patient's cornea or lens. The underlying cause of this abnormality is still unknown. Researchers know genetics play a factor in astigmatism. The condition is often present at birth and can develop later in life.

Keratoconus, a rare disease that causes corneas to thin or bulge out, can also cause astigmatism. The condition leads to cloudy vision and sensitivity to light. The origins of the disease are unknown but are likely hereditary.

Other circumstantial factors that can lead to astigmatism include:

• Eye injury

• Eye surgery

• Other eye diseases

• Chronic eye rubbing

The most common symptom of astigmatism is blurry vision. Patients may have trouble seeing fine details.

Other symptoms include:

• Eyestrain

• Seeing glare or halos around light

• Headaches

• Eye discomfort

• Squinting to improve vision
  

The presence of one or more of these symptoms doesn’t necessarily mean a patient has astigmatism. If you have symptoms, visit your eye doctor for a formal diagnosis.

An ophthalmologist diagnoses astigmatism through a comprehensive eye exam. During the exam, the doctor will conduct some tests to determine the diagnosis, including:

• Eye Chart: Used to test a patient's visual acuity.
  

• Refraction Test (Autorefractor): Measures how well a patient’s eyes work by shining a light and seeing how light enters and bends.
  

• Keratometry: A way for a doctor to measure the curvature of a patient’s eye. This is done by looking through an instrument called a Keratometer.

Astigmatism does not go away naturally. Mild forms may not require treatment, but astigmatism cannot be corrected on its own.

However, if astigmatism begins to affect a patient's vision, there are several treatment options available.

Astigmatism can be corrected with a variety of treatment options. The method will vary depending on the patient, and the severity of their symptoms.

Eye glasses: Prescription eyeglasses are the most common and least invasive treatment. Glasses provide lenses that compensate for astigmatism. The lens will help bend light and allow it to enter the eye properly.

Contact lenses: Prescription contact lenses are another common form of treatment. Eye doctors typically prescribe “toric lenses,” a special soft type of contact lenses.

Orthokeratology: Patients can also use a treatment called “orthokeratology.” In this treatment, patients wear a rigid lens at night to even out the curvature of the eye. Patients will wear the lenses less frequently as their eyes adjust to the shape.

Patients must be cautious with this treatment as it can lead to corneal ulcers and loss of vision. It is important to discuss this option with an ophthalmologist before initiating therapy.

During refractive surgery, a surgeon uses a laser to reshape the curvature of a patient’s cornea. This helps reduce refractive errors and may give patients with astigmatism freedom from glasses and contacts. The most common refractive surgeries used to treat astigmatism are:

LASIK: Laser-assisted in situ keratomileusis (LASIK) is the most common surgical treatment for astigmatism. During LASIK, a surgeon treats the condition by reshaping a patient’s cornea.

LASEK: In laser-assisted subepithelial keratectomy (LASEK), the surgeon adjusts the eye by making an incision in a thin part of the cornea called the epithelium. They then reshape the cornea and reposition the epithelium.

PRK: Photorefractive keratectomy (PRK) is a procedure similar to LASEK where the surgeon removes the epithelium to operate on the cornea. However, in PRK the doctor allows the tissue to grow back naturally and adjust to the eyes' new shape.

Refractive lens exchange (RLE): This refractive surgery is recommended for patients over 40 and is identical to cataract surgery. During the procedure, a surgeon will replace a patient’s natural lens with an artificial intraocular lens (IOL) which can help correct astigmatism.