For what keratoconus is and how scleral lenses help, see the keratoconus condition page. This page gathers the numbers.
How common it is
Prevalence estimates for keratoconus vary more than tenfold. That’s not because the disease is changing so much as because studies count it in very different ways.
| Study | Population | How cases were found | Estimate |
|---|---|---|---|
| Olmsted County, Minnesota, 1935–1982 | US county residents | Clinical diagnosis in medical records | 54.5 per 100,000[3] |
| Worldwide meta-analysis, 29 studies | 7.2 million people in 15 countries | Varied by study | 1.38 per 1,000[2] |
| Netherlands nationwide registry | 4.4 million insured people | Insurance diagnosis codes, then modeled | 1 in 375 (265 per 100,000)[1] |
| Raine Study, Perth, Australia | 1,259 20-year-olds | Corneal imaging of every participant | 1.2%, or 1 in 84[4] |
Why the gap? Older studies relied on people who already had a diagnosis, which misses mild cases. The Dutch study counted diagnoses in a modern insurance database and estimated lifetime prevalence from yearly new cases, average age at diagnosis, and life expectancy; its figures were 5 to 10 times higher than earlier population studies.[1] The Raine Study scanned every participant’s cornea, so it picked up cases people may not have known about, and its authors describe its result as one of the highest reported in the world.[4] Treat any single number as a rough guide for its own population.
New cases. In the Dutch registry, about 1 in 7,500 people aged 10 to 40 were newly diagnosed each year (13.3 per 100,000).[1] In Olmsted County, the average yearly incidence across all ages was 2.0 per 100,000.[3]
Who gets it
Age. In the Dutch registry, the average age at diagnosis was 28.3.[1] In Olmsted County, incidence was highest in the younger age groups.[3]
Sex. In the Dutch registry, 60.6% of people diagnosed were male.[1] In the worldwide meta-analysis, studies that reported sex found 20.6 per 1,000 in men and 18.33 per 1,000 in women.[2] (Those sex-specific figures come from a smaller subset of studies than the overall 1.38 per 1,000, so they can’t be compared directly with it.) In Olmsted County, incidence didn’t differ significantly by sex.[3]
Risk factors. The worldwide meta-analysis found these associations, expressed as odds ratios (how much more likely people with the factor were to have keratoconus):[2]
| Factor | Odds ratio |
|---|---|
| Family history of keratoconus | 6.42 |
| Eye rubbing | 3.09 |
| Eczema | 2.95 |
| Asthma | 1.94 |
| Allergy | 1.42 |
An odds ratio shows an association, not proof of cause. In the CLEK study of 1,209 patients, 13.5% reported a family history of keratoconus and 53% reported a history of atopy (allergic conditions).[5]
One eye or both. At diagnosis in Olmsted County, keratoconus appeared in one eye in 41% of patients and both eyes in 59%.[3] The keratoconus page explains why specialists now consider it a two-eye disease even when one eye looks normal at first.
How often it gets worse
The CLEK study (Collaborative Longitudinal Evaluation of Keratoconus) followed more than 1,000 patients at 16 centers for eight years.[6]
- On average, corneal steepness increased slowly: an expected 1.44 to 1.60 diopters over eight years, depending on the measure.
- About a quarter of patients (24.8% on one measure, 24.1% on another) had at least one eye steepen by 3 diopters or more.
- Younger age and poorer vision at the start predicted faster change.[6]
CLEK patients were adults, about 39 years old on average at entry, and younger age predicted faster change.[6] In the KERALINK trial of 60 patients aged 10 to 16 with progressive keratoconus, the disease progressed during the 18-month trial in 43% of those given standard care, compared with 7% of those who had corneal cross-linking.[9]
Progression also affects lens wearers. In a study of 157 keratoconus eyes wearing scleral lenses, 14.6% lost some of their best lens-corrected vision during the study period, all because the keratoconus progressed.[14]
How often it leads to a transplant
Figures depend heavily on where patients were seen.
- CLEK study, 8 years. Of 1,065 patients with no transplant at the start, 12% had one in at least one eye: 9.3% in one eye and 2.5% in both. Younger age, steeper corneas, worse vision, scarring, and poorer contact lens comfort predicted a transplant.[7]
- Moorfields Eye Hospital, London, 1994. Among 2,723 patients managed by the hospital’s contact lens service, followed for an average of 4.5 years, 21.6% had been grafted by the end of the study. Specialist centers tend to see more advanced cases.[8]
- Olmsted County, Minnesota. The chance of going more than 20 years after diagnosis without a transplant was greater than 80%.[3]
Transplants are falling. In the Netherlands, about 25% fewer corneal transplants for keratoconus were performed in the three years after cross-linking was introduced than in the three years before (201 vs 269).[10]
In the US, the Eye Bank Association of America reported 1,967 transplants for keratoconus and other ectasias using US eye bank tissue in 2024, 4.0% of all US corneal transplants and the sixth most common reason for one. The EBAA describes a thirteen-year decline from a high of 8,071 in 2011 and relates it to cross-linking and improved rigid lens fitting.[11] Reports before 2017 combined tissue used in the US and abroad, so that long-term comparison is approximate. Of the 2024 keratoconus transplants, 91.2% were full-thickness and 8.8% partial-thickness (anterior lamellar).[11]
Lens use in keratoconus
- Rigid lenses are the mainstay. In the CLEK study, 65% of patients wore rigid gas-permeable contact lenses.[5]
- Scleral lenses are growing. At one US academic medical center, no keratoconus patients were using scleral lenses in 2010; by 2020, 22% were. Corneal rigid lenses were still the most common at 60%. Scleral lenses were prescribed for the most advanced disease.[13]
- They can stand in for surgery. At a Belgian university clinic, 40 of 51 eyes with severe keratoconus that were prescribed scleral lenses instead of being referred for a transplant were still wearing them after about two and a half years.[12]
For more on how scleral wearers fare, see scleral lens outcomes research and corneal transplants and scleral lenses.
Common questions
How common is keratoconus?
It depends on the study. A Dutch insurance database estimated about 1 in 375 people. A worldwide review put it at 1.38 per 1,000. An Australian imaging study of 20-year-olds found 1 in 84. Studies that scan corneas directly tend to find more cases than studies that count existing diagnoses.
At what age is keratoconus usually diagnosed?
In a Dutch nationwide registry, the average age at diagnosis was 28.3. Incidence was measured in people aged 10 to 40, the age range the researchers treated as relevant for new diagnoses.
Is keratoconus more common in men?
In the Dutch registry, 60.6% of people diagnosed were male. A worldwide review found slightly higher prevalence in men than women in studies that reported it, and an older Minnesota study found no significant difference by sex.
What are the chances I'll need a corneal transplant?
Most people with keratoconus don't need one. In the CLEK study, 12% had a transplant in at least one eye over eight years. Rates are higher in specialist hospital clinics that see more severe cases, and they have fallen since cross-linking became available.
How many corneal transplants are done for keratoconus in the US?
The Eye Bank Association of America reported 1,967 transplants for keratoconus and other ectasias using US eye bank tissue in the US in 2024, 4.0% of all transplants.