All about Keratoconus

By Yasmin Tawndgee, Optometrist, Specsavers Manukau.

Image description: Close up of an eye, illustrating the typical steep, or cone-shaped cornea in keratoconus.

What is keratoconus?

Keratoconus is a condition that affects the cornea, the clear front surface of the eye. The cornea plays an important role in helping us see clearly, by focusing light onto the retina (the light-sensitive layer at the back of the eye).

In keratoconus, the cornea gradually becomes thinner and begins to bulge outwards into a cone shape. This change prevents light from being focused properly, resulting in blurred and distorted vision. The condition often begins in early teenage years and may continue into adulthood. It can affect one eye or both.

Early signs of keratoconus may include blurred vision, even with glasses. Other symptoms may include increased sensitivity to bright lights and glare. In more advanced cases, the cornea can become very thin and irregularly shaped, which may lead to scarring and more severe vision loss.

How is it caused?

The exact cause of keratoconus is not fully understood, but is believed to involve a combination of genetic and environmental factors. People with a family history, such as a parent or sibling with keratoconus, have a higher risk of developing the condition. Eye allergies may also play a role and frequent eye rubbing is known to worsen the condition.¹

Keratoconus affects both males and females, although it appears to be more common in males in New Zealand. It is also seen at higher rates in Māori and Pasifika communities.²

What can we do?

If you are experiencing blurred vision, especially with a family history of keratoconus, it is important to have your eyes checked. If suspected, there are several ways optometrists can diagnose, monitor and manage keratoconus.

Improving vision with glasses or contact lenses

In the early stages of keratoconus, glasses or soft contact lenses may be enough to correct your vision. However, as the condition progresses, these options become less effective.

In more advanced cases, rigid gas permeable (RGP) contact lenses are recommended. These are specialised hard contact lenses that fit over the cornea. They correct the irregular shape and create a smooth surface, which provides clearer vision compared to glasses or soft contact lenses.

In New Zealand, the Ministry of Health offers a subsidy for people with reduced vision due to keratoconus, which can help cover the cost of RGPs. Ask your optometrist for more information on this.

Ongoing management and treatment options

If keratoconus is suspected, further testing – such as detailed scans of the cornea – can confirm the diagnosis and determine how advanced the condition is. Regular eye examinations are important to monitor for any progression over time.

In many cases, keratoconus can be managed by updating glasses or contact lenses as needed. If eye allergies are present, your optometrist may prescribe antihistamine eye drops to help reduce itching and minimise eye rubbing.

If the condition is found to be progressing, a procedure called corneal cross-linking may be recommended. This is a surgical treatment involving the use of riboflavin (vitamin B2) eye drops and ultraviolet (UV) light. The aim of this procedure is to strengthen the cornea and help prevent further progression. Corneal cross-linking is a highly effective procedure, shown to slow or stop progression in a majority of cases.³

In more advanced situations where contact lenses are no longer effective or corneal scarring significantly affects vision, a corneal transplant (graft) using donor tissue may be required.

Conclusion

With early detection and the right management, most people with keratoconus are able to maintain good vision and continue with their normal daily activities. Regular eye examinations are key to monitoring the condition and ensuring the best possible outcomes.

If you have keratoconus and are finding everyday tasks more difficult, talk to your optometrist or eye doctor about how they can help. In some more advanced cases, you may be eligible for support from Blind Low Vision NZ. Talk to your eye specialist about a referral or contact Blind Low Vision NZ at 0800 24 33 33.

About the author

Yasmin Tawndgee is an optometrist based in Auckland, New Zealand. She currently practices at Specsavers Manukau and holds a Bachelor of Optometry from the University of Auckland and a Bachelor of Biomedical Sciences (Honours) from the University of Otago.

References

1. Singh, R.B., Koh, S., Sharma, N. et al. Keratoconus. Nat Rev Dis Primers 10, 81 (2024). https://doi.org/10.1038/s41572-024-00565-3.

2. Gokul, A., Ziaei, M., Mathan, J. J., Han, J. V., Misra, S. L., Patel, D. V., & McGhee, C. N. J. (2022). The Aotearoa Research Into Keratoconus Study: Geographic Distribution, Demographics, and Clinical Characteristics of Keratoconus in New Zealand. Cornea, 41(1), 16–22. https://doi.org/10.1097/ICO.0000000000002672.

3. https://www.aao.org/eye-health/treatments/corneal-cross-linking-2.