An activating system (110, 112) for initiating cross-linking in corneal tissue, comprising: a light source and one or more optical elements configured to activate cross-linking activity in a cornea treated with a cross-linking agent according to a three dimensional pattern; and a controller coupled to the light source and/or the one or more optical elements and configured to adjust wavelength, irradiance, dose, and/or on/off duty cycle, characterized in that: the light source and/or the and one or more optical elements are configured to deliver pulsed light illumination with different wavelength, irradiance, dose, and/or on/off duty cycle to different areas of the cornea leading to differing levels of corneal stiffening or corneal stiffening gradients, wherein one of the different areas includes an outer diameter of the cornea and another of the different areas includes a center of the cornea, and the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea are applied with different wavelength, irradiance, dose, and/or on/off duty cycle, and the controller is configured to adjust the wavelength, irradiance, the dose, and/or the on/off duty cycle to determine the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea. a light source and one or more optical elements configured to activate cross-linking activity in a cornea treated with a cross-linking agent according to a three dimensional pattern; and a controller coupled to the light source and/or the one or more optical elements and configured to adjust wavelength, irradiance, dose, and/or on/off duty cycle, characterized in that: the light source and/or the and one or more optical elements are configured to deliver pulsed light illumination with different wavelength, irradiance, dose, and/or on/off duty cycle to different areas of the cornea leading to differing levels of corneal stiffening or corneal stiffening gradients, wherein one of the different areas includes an outer diameter of the cornea and another of the different areas includes a center of the cornea, and the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea are applied with different wavelength, irradiance, dose, and/or on/off duty cycle, and the controller is configured to adjust the wavelength, irradiance, the dose, and/or the on/off duty cycle to determine the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea. the light source and/or the and one or more optical elements are configured to deliver pulsed light illumination with different wavelength, irradiance, dose, and/or on/off duty cycle to different areas of the cornea leading to differing levels of corneal stiffening or corneal stiffening gradients, wherein one of the different areas includes an outer diameter of the cornea and another of the different areas includes a center of the cornea, and the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea are applied with different wavelength, irradiance, dose, and/or on/off duty cycle, and the controller is configured to adjust the wavelength, irradiance, the dose, and/or the on/off duty cycle to determine the pulsed light illumination in the outer diameter of the cornea and the pulsed light illumination in the center of the cornea.