In this prospective interventional case series, the authors investigate using supplemental oxygen delivery during epithelium-on corneal crosslinking (CXL) with specially designed oxygen delivery goggles. Twenty-seven eyes of 24 patients underwent epi-on CXL with Riboflavin and Ultraviolet-A irradiation. At six months follow-up, mean corrected distance visual acuity (CDVA) improved by one and two or more Snellen lines in 48% and 30% of patients respectively. The corneal higher order aberrations (HOAs) improved significantly. The mean steep keratometry (K2) showed significant flattening of -1.9 diopters. The authors hypothesise the improvement in CDVA to be due to anterior corneal surface regularisation, compensating for corneal HOAs mostly caused by posterior surface irregularity. A demarcation line indicating the depth of treatment was observed on corneal optical coherence tomography and slit-lamp examination. The authors found this line to be 30% deeper than in eyes treated with the epi-off CXL procedure. The authors indicate this is indirect evidence that supplemental oxygen effectively increases the overall epi-on treatment depth by increasing intraoperative stromal oxygen diffusion. This paper needs supplementation with longer-term follow-up and a larger cohort of cases.