keratoconus

What is keratoconus?

Keratoconus is a progressive eye condition which causes thinning to the cornea (the front surface of the eye), resulting in the cornea protruding forward into an irregular “cone-like” shape, which can lead to significant visual distortion. Keratoconus is diagnosed by corneal tomography/topography, which maps out the shape of the cornea.

Early in the course of the condition, visual changes can present as astigmatism. As the condition progresses, so does the irregularity, and patients may experience visual symptoms such as multiple images, streaking of lights, and light sensitivity.

Early cases of keratoconus may not require any management, or may be managed simply with spectacles. As the condition progresses, spectacles may be of little assistance, as the reduction in vision is not due to the prescription of the eye – but rather the “shape” of the eye being distorted. In these cases, corneal rigid lenses or scleral lenses are required, as these create a more “regular” front surface for the eye.

The prevalence of keratoconus in Australia is approximately 1 in 2000 people. Keratoconus tends to manifest in early adolescence, and can continue to progress, but will tend to stabilise in the mid-late 30s. If there is evidence of progression, a surgical technique known as corneal cross-linking (CXL) can be performed by a corneal specialist. CXL does not fix or cure the condition, rather the aim is to stabilise the condition and prevent further progression. Whilst we do not perform CXL here, we work closely with local corneal specialists who we can refer to for CXL.

In cases where the keratoconus is so advanced it cannot be managed with contact lenses, corneal grafting may be required. In this procedure, the diseased cornea is removed and replaced with a healthy, donor cornea. This is reserved for cases where all other options have been exhausted. Fortunately, patients will not go blind from keratoconus.

How is keratoconus diagnosed?

Keratoconus is a multifactorial, bilateral disease, but is also asymmetrical. Keratoconus results in “irregular” astigmatism, and in the early stages can be misdiagnosed as “regular” astigmatism. The presentation varies between individuals, as the less advanced or unaffected eye may go undiagnosed for years. Symptoms include blurry vision, haloes and shadows, particuarly in the evening.

Keratoconus is best detected through instruments that can measure the shape of the cornea. Instruments that are capable of measuring the corneal surface include corneal topography, corneal tomography and anterior-segment optical coherence tomography. These can measure the characteristic changes seen in keratoconus.

At Eyetech Optometrists, we utilise corneal topography, corneal tomography and anterior-segment optical coherence tomography to analyse the cornea and monitor for changes. Corneal topography is a non-invasive technique to measure the the front surface of the cornea. The ‘cooler’ colours (blues to greens) indicate areas that are flatter, whereas the ‘warmer’ colours, (oranges to red) indicate areas that are more curved, or where the ‘cone’ is.

Keratoconus can also be detected via slit lamp biomicroscopy. This is basically a microscope that we direct at the eye to view it in high magnification. Characteristic signs include thinning and forward protrusion of the cornea, more prominent corneal nerves, Fleischer’s iron line around the cone and Vogt’s limbal lines (corneal stress lines from the stretching).

Our Optometrists manage keratoconus and work closely with local corneal specialists should surgery be required. If you have further queries, please do not hesitate to book in for an appointment.

Keratoconus Australia is a support network for patients suffering from keratoconus. You can find more information about keratoconus on their website.

Contact lenses for keratoconus

In the early stages of keratoconus, when corneal irregularity is mild, vision may be adequately corrected with spectacles. Soft contact lenses can also be a suitable option at this stage. However, as the condition progresses and the cornea becomes increasingly distorted, these options often fail to provide sufficient visual correction. In such cases, rigid gas permeable (RGP) lenses—or other specialty lens designs—are typically required to achieve clearer, more stable vision.

Traditionally, keratoconus has been managed with corneal rigid gas permeable (RGP) lenses. These smaller lenses rest on the cornea—the clear, central part of the eye—and provide both excellent vision correction and a strong safety profile. However, they can sometimes be unstable, may dislodge more easily, and are susceptible to foreign particles becoming trapped beneath the lens. Additionally, they require a period of adaptation, which some patients may find challenging. That said, most individuals who persevere through the initial adjustment typically achieve long-term comfort and success.

For those who are unable to tolerate corneal RGP lenses—or who have occupations or lifestyles involving dusty, windy environments or high physical activity—alternative lens options may be more suitable. These include scleral contact lenses and hybrid contact lenses.

Scleral lenses are larger rigid lenses that vault over the cornea and rest on the sclera (the white part of the eye), while hybrid lenses combine a rigid gas permeable centre with a soft peripheral skirt. Both lens types offer enhanced stability, improved comfort, and are less likely to attract debris beneath the lens. They are also typically more comfortable from the outset, with a shorter adaptation period than corneal RGPs.

At Eyetech Optometrists, we fit all types of contact lenses and are committed to finding the solution that best suits your eyes, lifestyle, and comfort. Book a consultation with us to explore your options in detail.