Is Ortho-K Suitable for Astigmatism?

Astigmatism is a very common vision condition caused by an irregular curvature of the cornea or lens. I

nstead of being perfectly round like a basketball, the cornea is shaped more like a rugby ball, which bends light unevenly and results in blurred or distorted vision at all distances.

For many people, astigmatism is mild and easily corrected with glasses or contact lenses. In other cases, higher levels of astigmatism can cause more noticeable symptoms such as eyestrain, headaches, or difficulty focusing.

Orthokeratology (Ortho-K) is a treatment that uses specially designed rigid contact lenses worn overnight to temporarily reshape the cornea. During the day, vision can be clear without glasses or contact lenses.

While Ortho-K is often discussed in relation to myopia (short-sightedness), it can also be prescribed in certain cases of astigmatism. But how effective is it, and who might be suitable?

Understanding Astigmatism and Prescriptions

When an optometrist diagnoses astigmatism, two numbers in your prescription are particularly relevant:

• Cylinder (CYL) – the amount of astigmatism, measured in dioptres.
• Axis – the orientation of the irregular curve, measured in degrees.

These values help determine not only the type of glasses or lenses required but also whether Ortho-K is a realistic option.

How Ortho-K Works for Astigmatism

Standard Ortho-K lenses are designed to correct myopia by gently flattening the central cornea. However, because astigmatism involves irregular curvature in more than one direction, fitting Ortho-K for astigmatism is more complex.

• Mild to moderate astigmatism – In some cases, standard Ortho-K lenses can provide acceptable correction if the irregularity is not too high.
• Moderate astigmatism – Specially designed “toric Ortho-K” lenses may be considered. These lenses are customised to address differences in curvature between the two meridians of the cornea.
• High astigmatism – Current evidence suggests Ortho-K is less effective when astigmatism is high. Glasses, soft toric contact lenses, or other options may be more suitable in these cases.

It’s important to understand that outcomes can vary. Some people with astigmatism may achieve clear, stable vision with Ortho-K, while others may not experience the same level of correction.

Evidence and Limitations

Research shows that Ortho-K can be effective in reducing myopia progression in children, and there is also evidence supporting its use in mild to moderate astigmatism. However, results are more variable compared to myopia-only cases.

Studies suggest that Ortho-K can correct up to about -1.75 dioptres of astigmatism effectively. Beyond this level, the ability to provide clear and consistent vision decreases. Even when correction is possible, it often requires highly customised lens designs and close follow-up to achieve and maintain good outcomes.

Who Might Be Considered for Ortho-K With Astigmatism?

An optometrist may discuss Ortho-K as an option for astigmatism if:

• The degree of astigmatism is within a range where Ortho-K can reliably correct vision.
• The corneal shape and health allow for safe lens fitting (assessed with detailed corneal topography).
• The patient or parent is motivated to follow the daily lens care routine required.
• The individual is looking for a non-surgical, reversible option for clear vision during the day.

The Assessment Process

To determine whether Ortho-K is suitable for astigmatism, an optometrist will carry out a comprehensive examination, which usually includes:

• Refraction testing – to measure the prescription accurately.
• Corneal topography – detailed mapping of the cornea to assess curvature and irregularities.
• Ocular health check – to ensure the eyes are healthy and can safely tolerate contact lens wear.
• Discussion of goals and lifestyle – to evaluate whether Ortho-K is the right fit for the individual’s needs.

If Ortho-K is not likely to provide good results, other options, such as glasses or soft toric contact lenses, may be recommended instead.

A Balanced Approach

Ortho-K can offer clear daytime vision without glasses and, in some cases, can successfully address mild to moderate astigmatism. However, it is not suitable for everyone, and outcomes for higher astigmatism are more limited. The decision always comes down to a careful assessment of prescription, corneal shape, and lifestyle factors.

If you’re interested in finding out whether Ortho-K may be appropriate for astigmatism in your situation, book an appointment at Optometrist Parramatta. Our team will carry out a detailed examination, explain your options clearly, and help guide you toward the best solution for your vision and eye health.