Photodynamic therapy (PDT) is a minimally invasive technique utilized for the treatment of several ophthalmic conditions across species. In horses, ophthalmic indications have so far included neoplasia of the adnexa and ocular surface, Descemet’s membrane detachment, and immune-mediated keratitis (IMMK). PDT has the potential to serve as a therapeutic intervention for these and additional corneal diseases in horses, however safety and impact of treatment on the cornea have not yet been described. We aim to determine the safety and effects of PDT on corneal health via serial clinical examination, in vivo confocal microscopy (IVCM), ultrasound biomicroscopy (UBM), and histopathology.