A CXL expert, John Kanellopoulos developed the Athens protocol for keratoconus and ectasia, which combines laser normalization of the irregular cornea with cross-linking. He also introduced higher fluency cross-linking and prophylactic cross-linking with LASIK, a precursor to LASIK Xtra, and demonstrated how CXL helps in infectious keratitis, corneal melts and pseudophakic keratopathy.