Keratoconus is far more common in people with Down syndrome than in the general population, but nobody knows the true rate. The best evidence — a nationwide Norwegian registry of 4,342 people — found keratoconus in 5.5%, roughly 28 times the rate recorded in the same registry for everyone else. A review of 20 studies found reported rates anywhere from 0% to 71%, with the quality of evidence rated low throughout. No large screening study has ever been done in this group.
Every figure on this page was read in the original journal article cited, not in a press summary or another website’s citation. Where a number could not be traced to its source, we left it out. This page is a companion to our main reference, 57 Keratoconus Statistics for 2026, which covers prevalence, risk factors, progression, cross-linking and lens outcomes in the general population.
Why this matters. Keratoconus can be stopped with corneal cross-linking if it is caught early. It cannot be reversed once the cornea has scarred. In a group where the condition is an order of magnitude more common, and where communicating blurred vision may be harder, the case for looking rather than waiting for a complaint is strong.
What the evidence shows
01In Norway’s national registry, 5.5% of people with Down syndrome carried a keratoconus diagnosis.
This is the most reliable figure available, because it counted everyone in a mandatory national registry rather than patients who happened to attend a particular clinic. That removes the selection problem that distorts most estimates in this area — small hospital samples tend to over-count, because the people who turn up are the ones with symptoms.
02That is roughly 28 times the rate recorded for the general Norwegian population — and both numbers are floors.
This comparison is cleaner than most. The general-population figure comes from the same national registry, gathered by the same research group using the same method, so it is not the usual mismatch of a registry count set against a screening study. But both sides count only people who have actually been diagnosed. The real gap could be larger or smaller.
03Across 20 studies, reported rates ranged from 0% to 71%.
The problem that makes general keratoconus prevalence figures disagree by a factor of fifty is worse here. The studies differ in who they recruited, how many, at what age, and how they defined the disease — and the review’s authors rated the quality of evidence as low throughout. A figure quoted from this literature without its study design attached is close to meaningless.
04No large screening study has ever been carried out in this group.
This is the gap that matters. Every figure above comes from clinic records or registries, which count people already diagnosed. Scanning a large unselected population is the method that revised general keratoconus prevalence upward roughly tenfold — and it has never been applied here. Until it is, every number on this page should be read as a minimum.
05In one tomography-based cohort of 226 people aged 10 to 30, 12.4% had keratoconus.
Unlike the registry studies, this one actually imaged every participant rather than counting existing diagnoses — which is why it is worth reporting alongside them despite the much smaller sample. It sits well above the registry figure, as you would expect from a method that finds cases nobody had noticed.
What this means for families and clinicians
Two things follow from the evidence above, and one does not.
It follows that the rate is substantially elevated. Every study that looked, across every design, found more keratoconus in people with Down syndrome than in the general population. The size of the difference is uncertain; its direction is not.
It follows that current figures undercount. Registry studies count diagnoses. The one study here that imaged everyone found more than twice the registry rate. Whatever the true figure is, it is above 5.5%.
It does not follow that any single percentage should be quoted as the rate. A range of 0% to 71% across 20 studies is not a measurement — it is a description of how much the answer depends on how you ask. If you need one number for a patient leaflet, the Norwegian registry figure is the best-supported, and it should be given as a minimum with its method attached.
On screening. The authors of both studies above conclude that screening for keratoconus in people with Down syndrome should be considered, on the grounds that cross-linking can halt progression if the condition is found early. That is their recommendation, reported here as they made it. Whether and how to screen is a clinical decision for the treating practitioner.
How we verified this page
Each figure was read in the article cited. The two Norwegian studies and the review were read in full text; the tomography cohort was verified against the published abstract, which reports the figures used here. Arithmetic was reconciled rather than assumed: 238 of 4,342 is 5.4813%, matching the reported 5.5% and 5,481 per 100,000, and 28 of 226 is 12.389%, matching the reported 12.39%.
Where our arithmetic and an author’s wording differ, we say so on the page rather than silently picking one. The ratio of 5,481 to 192.1 is 28.5; the authors call it thirtyfold. Both appear above.
One figure was cut. A frequently cited study reporting keratoconus in 27.2% of 1,207 adults with Down syndrome appears in the review’s summary table, but we could not obtain the original paper, so it is not on this page. We would rather this page be shorter and right.
If you believe a figure here is wrong, we want to know.
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Every figure last checked against its source: 4 August 2026. Revision history: 4 August 2026 — first publication.
Specialty lenses for irregular corneas
Michigan Contact Lens is a specialty contact lens practice in Southfield, Michigan. We fit scleral lenses and other custom lenses for keratoconus and irregular corneas, including for patients who find standard lenses difficult to manage, and we see patients referred by optometrists and ophthalmologists across the state. If you are looking for a keratoconus specialist in Michigan, or you would like to discuss screening for a family member, our new patient information explains what a first visit involves.
To book or ask a question, contact us or call 248-545-2800.
