What happens if keratoconus is left alone? Why age matters for monitoring

If you or your child has just been told you have keratoconus, one of the first questions is usually: "What happens if we just watch it?" It is a fair question. Not every cornea changes at the same speed, and not everyone needs treatment straight away. A large review published in 2026 pulls together decades of research on keratoconus that was left untreated, and it gives a clearer picture of who tends to change faster and why regular, careful monitoring matters.

A quick note before we start: this article is based on the published abstract of the review. We were not able to read the full paper, so we have only used the numbers the authors report in their abstract.

What the researchers did

This was a systematic review and meta-analysis. In plain words, the team searched four large medical databases (PubMed, Embase, Web of Science and Scopus) up to 25 September 2025 for every study that followed untreated keratoconus eyes for at least six months and measured how the cornea changed over time. They then combined the results statistically.

• Studies found: 92 studies, covering 30,342 untreated keratoconus eyes.
• Studies pooled in the main analysis: 47.
• Follow-up: results were grouped into less than 12 months, 12 months, and more than 12 months.
• Comparator: there was no treatment group. The "comparison" is each eye with itself over time.
• Masking: the abstract does not describe whether measurements in the original studies were masked.

The authors used "random-effects" models, which assume the true amount of change differs somewhat from study to study, and they used meta-regression to look for factors that predicted faster change.

What they found

Keratoconus tended to steepen over time

The main measure was Kmax, the steepest point on the corneal map. On average, Kmax increased by:

• 0.28 D at less than 12 months
• 0.62 D at 12 months
• 1.21 D at more than 12 months

All three changes were statistically significant (P < .05). Other measures, including average curvature (Kmean), steep and flat keratometry, and the thinnest point of the cornea, also showed significant worsening beyond 12 months.

A P-value is a way of asking, "If there were really no change, how surprising would these results be?" A P-value under .05 means the result would be fairly unlikely by chance alone. It does not tell you how big or how important a change is for any one person.

Younger age and a steeper cornea predicted faster change

This is the part that matters most for families. The meta-regression found that younger age and a higher starting Kmean were linked with greater Kmax progression. In the analyses that used Pentacam tomography:

• each 1 D increase in baseline Kmean predicted a 0.54 D increase in Kmax at 12 months (P < .001)
• each 10-year increase in age reduced Kmax progression by 1.46 D (P < .001)

The authors also suggest that, compared with Kmax, starting Kmean may be a more reproducible predictor of later progression, and that tracking several measures together may help sort out who is at higher risk.

What this means for you

The overall message is that untreated keratoconus, on average, tends to keep changing, and the pace is often quicker in younger people. That is one reason we pay close attention to teenagers and young adults, which we cover in more detail in our article on early detection of keratoconus in teenagers.

It does not mean every eye will worsen, or that everyone needs treatment tomorrow. Averages hide a lot of variation. What it does support is a careful, measured approach:

• Sequential corneal maps. A single scan is a snapshot. Repeating tomography on the same device over time lets your optometrist see whether the shape and thickness of the cornea are genuinely changing.
• Looking at more than one number. Because Kmean and other measures add information, a good review looks at the whole map, not just the steepest point.
• Timely referral. If progression is documented, the next step may be a referral to an ophthalmologist to discuss corneal cross-linking, a treatment that aims to slow further steepening. Cross-linking is performed by an ophthalmologist, but the decision about when to refer is usually based on the records your optometrist has built up.

At Rose Optometry in Hamilton, our optometrists, including Jagrut Lallu and Jacqueline Rowe, focus on keratoconus care: diagnosis, documenting change with repeat corneal tomography, referring at the right moment, and fitting specialty lenses such as scleral lenses for clearer, more comfortable vision. You can read more about our keratoconus service.

What the studies can't tell us

• Abstract only. We have not seen the full paper, including the quality of the individual studies, how much they disagreed with each other, or details of the subgroup results.
• Observational data. These were studies of untreated eyes followed over time. They describe what tended to happen, not what will happen to a particular person.
• Study-level patterns. Meta-regression links average age and average Kmean in each study with average progression. Patterns across groups do not always hold for individuals in the same way.
• Different devices and definitions. Some figures come only from Pentacam-based analyses, and measurements from different machines are not always interchangeable.
• Not all studies were pooled. Only 47 of the 92 studies were suitable for the meta-analysis.
• Masking and selection. The abstract does not say whether measurements were masked, or how the people studied were chosen, which could affect the results.

The take-home message

Keratoconus that is left alone tends, on average, to change over time, and younger people and those with steeper corneas may change faster. The practical answer is not to panic, but to monitor properly with repeat corneal maps, look at the whole picture, and refer for an ophthalmologist's opinion if progression is confirmed. If you would like your corneas mapped and tracked, you can book a keratoconus assessment with our optometrists in Hamilton.

References

• Tsai TH, Hsu JH, Tsai CL, et al. Natural History and Progression of Untreated Keratoconus: An Updated Systematic Review and Meta-Analysis. Current Eye Research. 2026;51(8):881-899. PMID 41978273. https://doi.org/10.1080/02713683.2026.2651259