A system for treating an eye includes a light source configured to provide photoactivating light that photoactivates a cross-linking agent applied to a cornea. The system includes one or more optical elements configured to receive the photoactivating light and produce a beam that defines a spot of the photoactivating light. The system includes a scanning system configured to receive the beam of the photoactivating light and to scan the spot of the photoactivating light along a first axis and a second axis to form a scan pattern on the cornea to generate cross-linking activity.