Can cross-linking be repeated?

Another question we are asked again and again is can you repeat cross-linking? The answer to this is, in principle, “yes”. However, one has to analyze exactly why the operation has to be repeated:

  • In a classic epi-off CXL, in 3% to 7% of cases, the therapy does not respond. Here it is possible to repeat cross-linking after six months.
  • If the cornea deteriorates after epi-on CXL, cross-linking can also be repeated after six months.
  • If other factors have been added, such as pregnancy or thyroid disease, a case-by-case decision must be taken.

Even if the effect of cross-linking diminishes after a few years, the therapy can be repeated. Our group has made important contributions in recent years to understand what causes repeated cross-linking.


In a lab study, we were able to show that repeated cross-linking within a week does not improve corneal biomechanics. However, we know that in reality there are often months and sometimes years between the first cross-linking and the repeat procedure.


We published the case of a patient who we treated with CXL on both sides. One eye remained stable for years – we performed only regular check-ups. The other eye’s ectasia progressed, so we repeated the CXL. What happened? The twice-treated eye displayed a further marked improvement. In other words, the effects of the two treatments were additive.

First CXL
Second CXL




The ELZA Institute