Autorefraction: what to expect

• Autorefraction is a widely used test for estimating the eye’s prescription, and gauging the amount of myopia (near-sightedness) or hyperopia (far-sightedness) and/or astigmatism present.
• Autorefractors have gained popularity in modern eye clinics, because the measurements are quick and simple to take, and the results are usually accurate and unbiased.
• While autorefraction results provide a helpful starting point, a more precise measurement is obtained through further vision tests with an optometrist or eye doctor

Autorefraction is a test measure a person’s refractive error (prescription), using an instrument called an autorefractor. Refractive errors refer to vision conditions such as myopia (near-sightedness), where light isn’t focused accurately within the eye, leading to blurred vision. It’s a quick, simple, and non-invasive procedure that helps eye care professionals understand how well the eyes can focus light.1 

There are major benefits to autorefraction. Compared to other methods, it greatly reduces the time required for your eye care professional to determine the prescription. On top of that, it is accurate, efficient, reliable, and doesn’t rely on a patient’s responses.

In the vast majority of eye clinics, autorefraction is often used to obtain a starting point for prescription measurement. These results are later refined through more detailed eye tests, like subjective refraction, before the lens prescription is finalized.

Autorefraction has multiple uses, including:

• Assessing myopia (near-sightedness), hyperopia (far-sightedness), and astigmatism
• Determining eyeglass prescription
• Determining contact lens prescription
• Assessing children
• Assessing patients who have difficulty communicating or cooperating

Autorefraction is a quick, safe, and comfortable procedure for patients of all ages.

While sitting in front of the autorefractor machine, you will be asked to focus on a small image inside the device, such as a hot air balloon or a house. During this process, the image may appear to move in and out of focus. The autorefractor analyses the light that reflects from the back of the eye (retina) and how well it is focused. It then calculates the lens power needed to focus the light correctly, which serves as a baseline for determining the lens prescription.

The test itself takes only a few seconds, and may be repeated a few times to ensure the results are accurate and reliable.

The readings from autorefraction provide an indication of a person’s distance prescription. In other words, the results can suggest the presence of myopia (near-sightedness), hyperopia (far-sightedness), and astigmatism – as well as the amount of vision correction needed for each. However, autorefraction does not provide a reading for reading prescriptions, as this is determined separately through dedicated near vision tests.

A typical autorefractor printout may include:

• S (Sphere): Indicates near-sightedness (if negative) or far-sightedness (if positive). The larger the number, the greater the amount of vision correction needed.
• C (Cylinder): Indicates the amount of astigmatism, and can be shown with either a negative sign (-) or positive sign (+) depending on the machine.
• A (Axis): Indicates the orientation of astigmatism.

Autorefraction is considered an accurate, reliable, and repeatable method for preliminary vision screening. Research shows that for the average person, autorefraction can achieve an accuracy of within 0.50 dioptres (2 steps) of the final result.2  However, autorefraction can be less reliable in children compared to adults, due to differences in focusing ability.3 

This is why autorefraction is often used as a starting point for testing. An accurate prescription is important to ensure clear and comfortable vision in glasses or contact lenses. To obtain more definitive results, your eye care practitioner may opt to fine tune the prescription through manual testing, sometimes coupled with the use of specialized eye drops (cycloplegia).

It is important to note that autorefraction does not replace a proper eye examination. The final glasses or contact lens prescription is usually determined after further testing carried out by eye care professional.