Eye health: Astigmatism and your eyes

What is astigmatism?

Astigmatism is a common eye condition that's easily corrected by glasses, contact lenses or surgery.

Astigmatism is characterised by an irregular curvature of the cornea. This type of disorder is also known as a refractive error. Astigmatism occurs in nearly everybody to some degree. For significant curvature, correction is required.

A person's eye is naturally spherical in shape. Under normal circumstances, when light enters the eye, it refracts evenly, creating a clear view of the object. However, the eye of a person with astigmatism is shaped more like a rugby ball or the back of a spoon. For this person, when light enters the eye it is refracted more in one direction than the other, allowing only part of the object to be in focus at one time. Objects at certain distances can then appear blurred.

What causes astigmatism?

Astigmatism can be hereditary and is often present at birth. It can also result from previous eye surgery, trauma to the eye and certain congenital conditions.

What are the symptoms of astigmatism?

People with undetected astigmatism often experience headaches, fatigue, eyestrain and blurring of vision that is not necessarily associated with obvious far/short-sightedness. While these symptoms may not necessarily be the result of astigmatism, you should see an optician for an eye test if you are experiencing one or more symptoms.

How are astigmatisms diagnosed?

Your optician can diagnose astigmatism by a thorough eye examination. Astigmatism may occur with other refractive errors such as myopia (nearsightedness) and hyperopia (farsightedness). Unfortunately, astigmatism often goes undetected in school-age children.

Because astigmatisms may increase slowly, you should visit your optician for an eye test once a year. Opticians are trained specifically to determine and improve visual acuity with the prescription of glasses or contact lenses. Ophthalmologists are doctors who can provide total eye care, from examinations and vision correction to the diagnosis and treatment of disease through to medication and surgery.

How are astigmatisms treated?

Almost all degrees of astigmatism can be corrected with properly prescribed glasses or contact lenses. For a person with only a slight degree of astigmatism, corrective lenses may not be needed at all, as long as other conditions such as nearsightedness or farsightedness are not present. If the astigmatism is moderate to high, however, corrective lenses are probably needed.

• Corrective lenses (glasses or contact lenses). For astigmatism, special corrective lenses called toric lenses are prescribed. Toric lenses have greater light bending power in one direction than the other. After performing various tests, your optician will determine the ideal toric lens prescription for your astigmatism.
• Refractive surgery. Another method for correcting astigmatism is by changing the shape of the cornea through refractive or laser eye surgery performed by an ophthalmologist. While there is more than one type of refractive surgery, specific treatments are recommended on an individual basis.

Refractive surgery requires healthy eyes that are free from retinal problems, corneal scars and any eye disease. As technology progresses, it is becoming more and more important that you explore all options and possibilities before deciding which refractive surgery and treatment is right for you.