WHAT IS KERATOCONUS?
Keratoconus is a non-inflammatory, progressive eye condition which causes thinning of the cornea, the front surface of the eye. This causes the cornea to protrude forward, developing a irregular ‘cone’ like shape, which can lead to significant visual distortion.
Early in the course of the condition, visual changes can present as astigmatism. As the condition progresses, so does 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 will no longer help, 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, rigid gas permeable contact lenses or similar are required, as these provide a more ‘regular’ front surface to 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, and will tend to stabilise in the late 30’s. 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 the condition, however it will stabilise the condition and stop further progression.
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.
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 and more information can be found on this website:
CONTACT LENS OPTIONS FOR KERATOCONUS
In early stage of keratoconus, where the degree of irregularity is mild, spectacles may be appropriate. In these cases, soft contact lenses may be an option. As the keratoconus becomes more pronounced and the cornea becomes more distorted, these options may be inadequate for correcting vision.
Once keratoconus reaches this level – rigid gas permeable (RGP) contact lenses or similar are required. Traditionally, keratoconus has been managed with corneal RGP lenses, which are lenses which fit within the cornea, i.e. are smaller than the coloured part of the eye. These lenses not only correct the vision but also afford excellent health, however they can be prone to ejection and prone to foreign particles. They also have an adaptation period which some patients may struggle to get through. However, once patients have passed this adaptation period, they usually have few problems.
For patients that cannot tolerate corneal RGP lenses or for patients who work in windy, dusty environments or are very active, other lens options may be required. These include mini-scleral contact lenses and hybrid contact lenses.
Mini-scleral contact lenses are rigid lenses which extend over the cornea and onto the sclera (the white part of the eye). Hybrid contact lenses are lenses which incorporate a rigid gas permeable centre with a soft outer skirt. Both of these lenses afford greater stability and comfort as compared to corneal RGP lenses, and do not tend to attract foreign particles beneath the lenses.