What is astigmatism and is it dangerous?

Photo by Maria Carrasco on Unsplash

You’ve heard of people being short-sighted or long-sighted, but what about when someone has blurry vision at all distances? This type of refractive error is known as astigmatism.

Astigmatism isn’t dangerous – it simply means that the front surface of a person’s eye (the cornea) has a curvature shaped more like a rugby ball than a soccer ball. Light enters the eye through the cornea and bends (refracts) to focus on the light-sensitive tissue at the back of the eye (the retina). From there, a signal is sent to the brain, which then processes the image that we see. Normally the cornea’s curvature allows light entering the eye to focus at one point on the retina and this creates a clear, crisp image. When the cornea is shaped more like a rugby ball, light entering the eye focuses at two places on the retina and this leads to blurred vision.

How do I know if I have astigmatism?

The main symptom of astigmatism is blurry vision at all distances and it’s quite common to also experience eye strain and/or headaches. Most people with astigmatism have it from a young age, but it’s not uncommon to develop astigmatism later in life. Have your eyes assessed by an optometrist if you notice any of these symptoms.

Astigmatism can be diagnosed following a series of tests performed by your optometrist. To determine the clarity of your vision, you’ll be asked to read letters from a wall chart (known as a visual acuity test). Next, you’ll look through a series of lenses to determine the focusing power of your eyes. Your optometrist will then use a piece of equipment called a keratometer to measure the curvature of the front surface of your cornea.

Almost everyone will have some degree of astigmatism – it’s unlikely to have a perfectly smooth and round corneal surface – but for the majority of people, minor surface irregularities do not cause noticeable vision impairment.

When astigmatism does lead to blurred vision, your optometrist will prescribe glasses or contact lenses to correct the refractive error and restore clear vision.

Are glasses and contacts the only way to correct astigmatism?

Many people don’t realise there are vision correction procedures that can permanently correct astigmatism. Sophisticated technology that generates detailed 3D mapping of the eye’s surface (called corneal topography) allows us to correct an individual’s astigmatic error with high precision, restoring clear vision.

Laser eye surgery permanently reshapes the corneal surface using a cool-temperature laser, so that light entering the eye will focus at one point on the retina. For people who meet the eligibility criteria, laser eye surgery is considered a very safe elective surgical procedure. To be eligible for laser eye surgery, you need to be aged between 18 and 55, have had a stable glasses prescription for at least 12 months, have good general eye health and not be pregnant or breastfeeding. You can find out more about laser eye surgery here.

Implantable collamer lenses (ICL) are like glasses or contacts in that they change how light bends and focuses in your eye. The difference is that the tiny, flexible lens is inserted inside your eye via a small sutureless incision during a quick surgical procedure. The lens is custom-made for your eyes and can be replaced or removed if necessary – there are no permanent changes to your eye.

Intraocular lenses (IOLs) are used to replace the eye’s natural lens during cataract surgery or refractive lens exchange. In addition to correcting presbyopia (age-related long-sightedness), premium IOLs can be designed to correct your astigmatism and give you clear vision at all distances, removing the need for glasses for reading or any other activities. This particular type of IOL is known as a toric lens. Individuals who have non-toric IOLs (and therefore still need glasses to correct their astigmatism) can have a secondary procedure such as laser eye surgery or have their IOL replaced with a premium lens to eliminate their need for glasses. IOLs are generally reserved for people aged over 50 because a younger person’s natural lens is superior to the currently available artificial lenses.

Which vision correction option is right for me?

This depends on a number of factors such as your age, the health of your eyes and your lifestyle needs and preferences. Glasses or contacts are the best choice for some people, while for others a permanent solution that offers clear vision can open up a world of possibilities.

The best thing to do is to book a consultation with an optometrist or an ophthalmologist who specialises in vision correction (e.g. refractive surgery and cataract surgery). Following a comprehensive assessment and a detailed discussion about your options, you’ll be able to make an informed decision about the solution that’s right for you.

 

Occasionally we publish posts from industry partners; in this case Vision Eye Institute. Dr Patrick Versace is a highly experienced refractive and cataract surgeon who specialises in laser eye surgery and cataract surgery. He has expertise in presbyopia correction, corneal inlays and multifocal intraocular lenses. Dr Versace practises at Vision Eye Institute Bondi Junction and Vision Eye Institute Hurstville.

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