As a procedure that involves placing the ICL into the limited internal space of the eye, the main risks are to the surrounding structures during the surgery as well as post-surgery.
Firstly, the clear, natural lens of the eye may develop a cataract due to the ICL surgery, although this risk seems to be lowered with the new ICL design (EVO Visian ICL with KS port).
Secondly, there is also a risk of the eye developing glaucoma, either temporarily after the surgery, or gradually in the long term.
These risks are small but are important enough to warrant yearly reviews for post-ICL eyes, to prevent possibly irreversible loss of vision such as from glaucoma.
Other risks such as loss of vision from cornea cell loss, internal infection (called endophthalmitis) or retina tear and detachment are all exceedingly rare, but owing to their potential severity, need to be carefully thought through.