Astigmatism

Symptoms: 
  • Distortion or blurring of images at all distances
  • Headache and fatigue
  • Squinting and eye discomfort or irritation

The symptoms described above may not necessarily mean that you have astigmatism. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam

Tests to diagnose: 

Astigmatism is diagnosed by an optometrist (a licensed healthcare professional who diagnoses vision problems and eye diseases), or an ophthalmologist (a medical eye doctor who provides medical and surgical treatment of vision problems and eye diseases), through a comprehensive eye examination. Tests optometrists and ophthalmologists may use during your eye examination to diagnose astigmatism include:

Visual Acuity Assessment Test (VAT)

During a VAT, your optometrist or ophthalmologist will have you read letters from a chart at a specific distance to determine how well you can see the letters.

Refractor Test

A refractor test is performed using a machine called an optical refractor. The machine has multiple corrective glass lenses (like eyeglass lenses) of different strengths. Your optometrist or ophthalmologist will ask you to read a chart while looking through different strength lenses on the optical refractor, until he finds a lens that appropriately corrects your vision.

Keratometry

During a keratometry examination, your optometrist or ophthalmologist will look at your eye through a keratoscope machine to detect and measure the curvature of your cornea.

Treatment: 

There are three ways to treat astigmatism: glasses, contact lenses, and surgery.

Glasses and contact lenses for people with astigmatism have an extra component called a toric lens. This bends light to counterbalance the effects of astigmatism. These lenses are usually a bit more expensive.

Toric contact lenses may be slightly heavier on one side. This side slips to the bottom of the eye, ensuring that the right part of the lens is over the right part of the eye. Some people have found these lenses less comfortable than normal lenses. But contact lens technology is improving all the time, so if you found toric lenses uncomfortable in the past, you might not if you try them now.

Surgery treats astigmatism by reshaping the surface of the eye. For people who are also nearsighted, the surgery can correct both the nearsightedness and astigmatism at the same time.

There are a few basic types of operations, which are usually done in an eye clinic:

Laser-assisted in situ keratomileusis (LASIK)
Laser-assisted subepithelial keratomileusis (LASEK)
Photorefractive keratectomy (PRK or PK)
Radial keratotomy (RK)

With LASIK, the doctor makes a small cut into the top layer of the cornea, then folds back this layer like a flap. A laser is then used to mould the inner tissue of the cornea underneath into a better shape. The flap is then replaced.

PRK is done with a computer-guided laser. A computer-controlled laser removes the epithelium (the very top protective layer over the cornea in the front of the eye), then reshapes the cornea by ablating (destroying) tissue in the periphery or outer part. The result is a cornea that is shaped to refract (bend) light correctly.

LASEK is a variation of LASIK and PRK. With LASEK, the flap created in the cornea is thinner, and the laser moulds the outer layer of the cornea (the epithelium).

RK is not used as often now that PRK and LASIK are available. It may sometimes be used for people with severe astigmatism and is performed by a surgeon or a special machine. Based on the results of an eye test, an ophthalmologist makes precise cuts with a tiny diamond blade in a spoke formation around the cornea. These cuts cause the tissue to relax, flattening the cornea into the desired spherical shape. RK, though cheaper than laser surgeries, is just as effective and safe at treating astigmatism. People with myopia, however, tend to have better vision after PRK. There is also some risk that RK may lead to farsightedness later on.

Surgery can only be performed on uninfected healthy eyes. It's not suitable for children and teenagers, whose vision is still changing.

Eye operations don't always produce the desired results. Study results vary, but most people who have laser surgery have improved vision. It is important to realize, however, that some people do not notice any improvement in their vision, and a few end up with poorer vision.

Laser surgery can reduce the quality of your best corrected vision (the absolute best you could see with the right lenses). It can also impair night vision. In addition, the eye can change again after the operation. Sometimes, it heals from surgery into much the same shape it had before, producing only temporary improvement. Because eye doctors like to err on the side of caution, they may under-correct vision, and you may need follow-up procedures.

Finally, although laser surgery has been around for over 15 years, we still don't know the long-term consequences. Most people are still seeing fine 10 years after PK, but we don't know how they'll be seeing 30 years later. While there's no reason to believe they'll have problems, we can't be absolutely sure. It is important to discuss potential complications thoroughly with an eye doctor before opting for laser surgery.