Menu
This is mainly related to how old the patients were when they first underwent cross-linking. In simple terms, the younger the patient is at the first cross-linking, the higher the likelihood that they will need a second treatment after 7−8 years.
The cornea is completely rebuilt every 7−8 years – a fact that has only recently come to light. What this means is that no original cross-links are left after this time. If the patients were still very young at the time of the first cross-linking, they are still young enough after 7−8 years for keratoconus to re-emerge.
The following video explains the connections.
Background
Fifteen years into the clinical application of corneal cross-linking, we are collecting a growing number of long-term results from patients of all age groups, including children and adolescents. The question is whether or not it will become necessary to retreat some of these patients because the cross-linking effect might fade over time.
What is the turnover rate of collagen in the cornea?
We know nowadays that the collagen turnover rate is 6 to 7 years. In other words, after this timespan, the original stiffening effect of the CXL procedure has worn off, and the only factor protecting the cornea is the natural stiffening related to the patient’s age.
Young people more at risk
The turnover rate of collagen explains why patients who were extremely young at the age of the CXL procedure (i.e. 11 years old) are at a greater risk once the CXL effect has worn off 6 to 7 years later: they will be only 17 to 18 years old, so still at an age where the disease can be very active. In contrast, a patient who is 28 years at the time of the first CXL procedure, will be 35 years once the CXL effect has worn off: an age at which typically the progression of keratoconus will slow down anyway.
Keep young patients in close follow-up
This is why young patients should have annual following-ups and be retreated as soon as first signs of reactivation of keratoconus occur.
