Refractive error is a very common eye disorder that makes it hard to see clearly.

Refractive error occurs when light passing through the eye does not focus correctly on the retina at the back of the eye. This creates blurred vision.

The most common forms of refractive error are:

• Short sightedness (myopia), which makes objects in the distance look blurry.
• Long sightedness (hypermetropia), which makes close up objects look blurry.
• Astigmatism, which results in blurred or distorted vision either close up or in the distance.
• Presbyopia, which occurs with age and makes it hard to see objects up close.

Refractive error causes half of all vision problems in Australia.

Between 200,000 and 300,000 Australians are not seeing as clearly as they should be because of under-corrected refractive error. For example, wearing glasses with an out of date prescription.

Refractive error typically starts during childhood, when the eyes are still developing. The exception is presbyopia, which is more common in people aged 40 years and over.

Refractive error is caused by:

• too much or too little growth in the length of the eyeball
• problems with the shape of the cornea, or
• ageing of the lens.

Both genetic and environmental factors contribute to refractive error.

Anyone can develop refractive error. But you’re at higher risk if you have family members who wear glasses or contact lenses.

The most common symptom is blurry vision. Other symptoms include:

• Double vision
• Hazy vision
• Seeing a glare or halo around bright lights
• Squinting
• Headaches
• Sore or tired eyes
• Trouble focusing when reading or looking at a computer.

Even if you don’t have these symptoms, it’s important to get your eye checked regularly. This is to make sure your vision is as clear as possible.

If you already wear glasses or contact lenses and have these symptoms, you may need a new prescription.

Your eye healthcare provider will check for refractive error as part of a routine eye test. They will ask you to read letters that are up close and far away. They will also perform a procedure to measure the refraction of your eyes. An eye test takes around 30 minutes.

Prescription glasses or contact lenses can treat vision problems caused by refractive error.

Laser eye surgery can also correct refractive error. Your eye healthcare provider can advise if surgery may be an option for you.

Refractive error is not completely preventable. But you can reduce your risk by avoiding long hours of close up activities, like staring at a computer screen.

Increasing the time spent outdoors may reduce the risk of short sightedness in children.

Our researchers are involved in a number of studies that strive to advance our understanding of myopia, one of the most common types of refractive error.

Professor Mingguang He, a Principal Investigator at CERA, is a world-renowned expert in the prevention and treatment of myopia. His study on myopia in China showed that spending more time playing outside could protect children from short-sightedness as they grow up. He also works on innovative treatments to slow down myopia progression in children.

Our Clinical Genetics Unit is also doing research to find the genes responsible for common eye diseases, including myopia.