By Dr. Adel Barbara, ophthalmologist and corneal and refractive surgeon
Keratoconus causes the cornea to become progressively thinner and more irregular. In adults, a diagnosis does not automatically mean that corneal cross-linking must be performed immediately; the central question is whether the condition is stable or continuing to progress. The recommendation is different for children and young people under 18: because of their high risk of progression, cross-linking is recommended at diagnosis, once the diagnosis has been confirmed and suitability for treatment has been assessed.
What is the purpose of monitoring?
Monitoring is not the absence of treatment. Its purpose is to identify genuine corneal change at the right time, before further meaningful loss of vision occurs.
Follow-up may include:
- Visual-acuity and refraction testing.
- Corneal topography or tomography.
- Measurement of corneal thickness.
- Assessment of the anterior and posterior corneal surfaces.
- Careful comparison with previous examinations.
A single examination provides a snapshot, but it usually cannot establish whether keratoconus is progressing. Reliable progression assessment requires good-quality measurements obtained over time under comparable conditions.
Patients should also follow their doctor’s instructions about discontinuing contact-lens wear before corneal imaging, because lenses can temporarily alter corneal shape and affect the results.
When may monitoring be sufficient?
In patients aged 18 or older, continued observation may be considered when:
- Corneal maps remain stable compared with earlier examinations.
- There is no meaningful change in corneal thickness or shape.
- There is no otherwise unexplained decline in visual acuity.
- The spectacle or contact-lens prescription is not changing rapidly.
- The patient can return for reliable, regular follow-up.
Age is important, but it is not the only criterion. In children and young people under 18, keratoconus tends to progress more rapidly and aggressively. Therefore, after confirming the diagnosis and assessing suitability, cross-linking is recommended at diagnosis without waiting for progression to be demonstrated. Progression can also occur later in life, so stability should not be assumed from age alone.
How is progression identified?
No single measurement is appropriate for every patient. The ophthalmologist considers several findings together, including:
- Change in anterior corneal curvature.
- Change in the posterior corneal surface.
- Corneal thinning or a change in the thickness profile.
- Increasing astigmatism or refractive change.
- Reduced best-corrected visual acuity.
- A consistent pattern across repeat examinations.
A small change in one number does not always indicate true progression. Scan quality, dry eye, contact-lens wear and differences between imaging devices can influence the results. The decision must be based on the complete clinical picture.
When is corneal cross-linking considered?
In patients aged 18 or older, cross-linking is considered primarily when there is evidence that keratoconus is progressing. Children and young people under 18 have a higher risk of progression; cross-linking is therefore recommended at diagnosis, once the diagnosis has been confirmed and medical suitability assessed, without waiting for progression to be documented on repeat examinations.
The procedure uses riboflavin and UVA light to create additional bonds within corneal collagen and increase biomechanical strength.
Its principal purpose is to stabilize the cornea and reduce the risk of further progression. Cross-linking is not laser vision correction and does not guarantee better vision. Some patients may experience a degree of corneal flattening or visual improvement, but that is not the treatment’s primary objective.
Stopping progression and improving vision are different goals
Two separate questions must be considered:
- Does the disease need to be stabilized?
- What is the best way to improve functional vision?
Cross-linking is primarily intended to stabilize the cornea. Glasses and specialist contact lenses can improve vision, but they do not stop disease progression.
For selected patients, additional visual-rehabilitation options may include scleral lenses, intracorneal ring segments or CAIRS. These approaches are not appropriate for every eye and may sometimes be planned in stages together with cross-linking.
When should an examination not be delayed?
Earlier recognition of progression provides an opportunity to intervene before the cornea becomes more irregular or thinner and before further meaningful loss of visual quality occurs.
An assessment is particularly important when there are:
- Frequent prescription changes.
- Increasing astigmatism.
- Blurred or distorted vision.
- Halos or glare at night.
- Vision that is not adequately corrected with glasses.
- An abnormal corneal map.
- A family history of keratoconus.
- Significant eye rubbing or chronic ocular allergy.
In summary
In patients aged 18 or older, not every diagnosis of keratoconus requires immediate intervention, but every diagnosis deserves structured assessment and follow-up. For children and young people under 18, the high risk of progression supports cross-linking at diagnosis, once the diagnosis has been confirmed and suitability assessed. In adults, the choice between monitoring and cross-linking considers age, clinical examination, visual quality and consistent change in corneal structure.
For adults, the aim is to avoid unnecessary treatment while also not missing progression at a time when the cornea and vision can still be protected.
Professional sources
- American Academy of Ophthalmology — Corneal Ectasia Preferred Practice Pattern
- Global Consensus on Keratoconus and Ectatic Diseases
- EyeWiki — Corneal Cross-Linking
- National Eye Institute — Corneal Conditions
This article provides general information and does not replace an examination or individualized medical advice.