A system for treatment of corneal tissue includes one or more light sources that generate excitation light delivered to corneal tissue treated with a cross-linking agent. The excitation light causes the cross-linking agent to fluoresce by emitting an emission light at a plurality of emission wavelengths. The system includes an image capture system that captures image(s) of the corneal tissue. The image(s) indicate at least two of the emission wavelengths. The system includes a controller that receives the image(s). The controller: identifies each of the at least two emission wavelengths in the image(s); determines, from the image(s), respective characteristics associated separately with each of the at least two emission wavelengths; and provides information relating to cross-linking activity generated by the cross-linking agent in the corneal tissue based on the respective characteristics associated with each of the at least two emission wavelengths.