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Backroom Ops websiteWhat keratoconus is, who is at risk, how it is diagnosed, and what the evidence says about cross-linking, specialty contact lenses and corneal transplants.
Every clinical statement in this guide is referenced to a peer-reviewed paper whose full text was checked. Last reviewed October 2026.
Keratoconus is an eye condition in which the cornea, the clear window at the front of the eye, becomes thinner and gradually bulges forward.[1] It usually affects both eyes, but often one eye more than the other.[1]
People with keratoconus often notice blurred or distorted vision, or find that their glasses prescription keeps changing. These symptoms have other causes too, so an eye examination is the way to find out what is going on.
Keratoconus is usually diagnosed in the teenage years and tends to keep getting worse until about the thirties.[2] It can also start before puberty, and getting worse after the age of 40 is not unusual.[1]
Estimates of how common it is vary widely, from fewer than 1 to as many as 40 people in every 1,000, depending on the population studied and how keratoconus is measured.[1] One widely quoted global figure is about 1.38 people per 1,000.[2]
The strongest known risk factors are eye rubbing and having a family member with keratoconus, and allergic conditions are also linked.[1] In one review, eye rubbing was linked to about five times the odds of keratoconus, a family history to nearly seven times the odds, and allergic conditions to about twice the odds.[1]
Eye rubbing is a risk factor you can change, so specialists advise against it.[1] Getting itchy, allergic eyes treated matters too, because itch can lead to rubbing.[1]
Children and teenagers need particular attention. Keratoconus is often more advanced when it is first found in children than in adults, and it tends to progress faster.[3] People who are younger, have allergies, rub their eyes, or have Down syndrome need closer monitoring for progression.[1]
Keratoconus is found with a corneal scan (corneal topography or tomography), a painless test that maps the shape of the cornea. A clinical guideline suggests a corneal scan for people with reduced vision who also have a family history of keratoconus or an allergic condition, to help detect it early.[1]
Whether keratoconus is getting worse is judged by combining clinical measurements with repeat scans over time.[1] That is why regular follow-up visits are so important after a diagnosis.
Corneal cross-linking (CXL) is a treatment for keratoconus that is getting worse. A clinical guideline suggests CXL for children and adults with progressive keratoconus, because it may halt or slow progression and, in some cases, may improve the shape of the cornea and vision.[1] The guideline rated the certainty of this evidence as low.[1]
In a small placebo-controlled trial of 29 patients, treated corneas flattened slightly on average (by 0.35 dioptres a year), while on average untreated corneas slowly steepened (by 0.11 dioptres a year).[4] Not every untreated eye got worse.[4] All treated eyes developed a temporary haze in the cornea, which had mostly cleared by three years.[4]
There are two main types of cross-linking. Standard 'epithelium-off' CXL flattens the cornea more, while 'epithelium-on' CXL has a lower risk of some side effects, such as lasting cloudiness of the cornea, but a smaller flattening effect.[1] Your eye specialist should explain the possible side effects before treatment.[1] Cross-linking is carried out by an ophthalmologist (eye surgeon), and your optometrist can refer you if it is needed.
In early keratoconus, glasses or soft contact lenses can work well. As the condition progresses, rigid gas permeable (RGP) or scleral contact lenses are often needed for the best vision.[5]
Scleral lenses are larger lenses that vault over the cornea and rest on a reservoir of tear fluid, so the fit does not depend on the shape of the cornea.[6] They can give excellent vision and significantly improve quality of life, particularly for people who cannot tolerate other types of lens.[5] Fitting specialty lenses can take several visits, so allow time to get them right.
One of the most widely used rigid contact lenses for keratoconus was designed in New Zealand. Hamilton optometrist Paul Rose, who started his practice in Hamilton in 1969, worked for more than a decade on a lens design and fitting system for keratoconus, going through 12 prototypes.[7] The result was the Rose K lens, which is now available in more than 90 countries.[8] In 2017 Paul Rose was made a Companion of the New Zealand Order of Merit for services to ophthalmology and optometry.[7][9] Rose Optometry in Frankton, Hamilton, describes itself as the home of the Rose K lens, which Paul Rose designed in the Waikato.[10]
The design has been tested against other lenses. In a randomised trial of 60 eyes with keratoconus, Rose K lenses improved vision as much as another rigid lens design (Soper), but were more comfortable, gave better contrast, and needed fewer trial lenses to fit: an average of 2, compared with 3.4.[11] The trial followed patients for three months, so it does not tell us about long-term wear.[11]
There is a government contact lens subsidy for people whose vision is reduced by keratoconus, and it can help cover the cost of rigid contact lenses.[12] Your optometrist or ophthalmologist claims it on your behalf: they must hold an agreement with Health New Zealand | Te Whatu Ora, and the subsidy pays towards supplying the lenses. If you only have an eye examination and no lenses are fitted, you pay for the examination yourself (checked October 2026).[13]
The subsidy does not cover everything. Expect to pay your optometrist additional fees for the fitting, on top of what the subsidy covers. Before anything is ordered, ask whether you qualify for the subsidy and ask for a written quote for the fitting appointments and the lenses.
In the past, it has been reported that more than 1 in 5 people with keratoconus eventually needed a corneal transplant.[3] This is a historical figure and not a current New Zealand rate. Today, the aim of regular monitoring and, where needed, cross-linking is to pick up progression early and stabilise the cornea.
A corneal transplant is reserved for advanced keratoconus with severe thinning or scarring of the cornea.[6] When a transplant is needed for the most advanced stage, a clinical guideline suggests a partial-thickness graft (called DALK) rather than a full-thickness graft, because full-thickness grafts had more rejection, raised eye pressure and cataract; this evidence was rated very low certainty.[1]
If your optometrist suspects keratoconus, a typical assessment includes:
Your optometrist will explain the results and how often you should be seen again. If there are signs that keratoconus is getting worse, you may be referred to an ophthalmologist to discuss cross-linking. It helps to bring your current glasses and any previous scan results or reports to each visit.
Useful questions to ask include: Is my keratoconus stable or getting worse? How will we tell if it changes? Which type of lens would give me the best vision? When should I come back?
Book an eye examination if:
Seek help the same day if you have a painful red eye, a sudden drop in vision, or pain and redness while wearing contact lenses.
Use our directory of New Zealand optometrists to find a practice near you. When you call, ask whether the practice has corneal scanning (topography or tomography) and fits specialty contact lenses such as RGP or scleral lenses.
This guide is general information and does not replace an eye examination.
Yes. Cross-linking may halt or slow keratoconus that is getting worse, and specialty contact lenses such as scleral lenses can give excellent vision.
Yes. Eye rubbing is one of the strongest known risk factors for keratoconus, so specialists advise avoiding it and treating itchy, allergic eyes.
A transplant is reserved for advanced keratoconus with severe thinning or scarring. Regular monitoring helps your eye care team pick up any change early.
It is worth asking. A family history is a strong risk factor, and keratoconus is often more advanced when first found in children and tends to progress faster.
Yes. A government contact lens subsidy can help cover the cost of rigid lenses for people whose vision is reduced by keratoconus. Your optometrist claims it, and you should expect to pay additional fees for the fitting on top of the subsidy, so ask for a written quote (checked October 2026).
Yes. Hamilton optometrist Paul Rose spent more than a decade developing the Rose K lens for keratoconus, and it is now available in more than 90 countries.
Compare the 93 practices in this guide by the same published criteria.
This is not a practice listing or a ranking.
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