Systems and methods for treatments of an eye with a photosensitizer

A method for treating corneal damage associated with a pathogen infection in an eye, comprising:

• identifying an eye infected by a pathogen;
• applying an eye drop formulation to an area of the eye infected by the pathogen, the formulation including:
• a photosensitizer;
• one or more non-ionic permeability enhancers;
• and
• at least one additive selected from the group consisting of iron, copper, manganese, chromium, vanadium, aluminum, cobalt, mercury, cadmium, nickel, arsenic, 2,3-butanedione, and folic acid;
• and
• delivering a dose of illumination having a fluence rate ranging from about 15 mW/cm2 to about 45 mW/cm2 in combination with pulsed oxygen to the area of the eye thereby photoactivating the photosensitizer and cross-linking corneal tissue at a depth that does not damage endothelium.