Purpose: To assess the epithelial-stromal healing process after corneal phototherapy with riboflavin and UV-A of corneal ulcers, which were resistant to medical therapy, by means of Anterior Segment Optical Coherence Tomography (OCT; iVue optovue).Procedure: 14 dogs (14 eyes), with corneal ulcer involving at least 1/3 of the stroma and not responding to medical therapy for at least 30 days, were included in this study. The corneal phototherapy consisted in the instillation of 0.1% riboflavin ophthalmic so lution on to the cornea for 20 minutes, followed by UV-A irradiation at 30 mW/cm2 for 3 minutes. Subjects underwent a complete ophthalmological examination on the day of treatment, after 7 days and then at an interval between 7 and 20 days until the resolution of the ulcer for a follow-up period up to 3 months. At each follow-up examination, the stromal and epithelial thickness of both the ulcerated area and the surrounding healthy areas were measured with OCT in order to evaluate the epithelial-stromal healing process.Results: Healing of the ulcerative corneal lesion was achieved in 12.5 ± 4 days after corneal phototherapy in all cases. The OCT assessment of corneal lesions was valuable to assess objectively the course of the healing process. Conclusions:OCT assessment provided useful information on corneal wound healing process after corneal phototherapy. The treatment has proven to be a safe and valid therapeutic option for chronic corneal ulcers no responders to medical therapy.