Abstract: Objective To compare the depth of demarcation line in iontophoresis-assisted corneal crosslinking (I-CXL) using 0．1% riboflavin-distilled water solution versus in I-CXL using 0．1% riboflavin-sodium lactate Ringer's solution for progressive keratoconus． Methods From January to July in 2013, clinical data about 11 patients (16 eyes) treated with I-CXL using 0．1% riboflavin-sodium lactate Ringer's solution were collected; and from August 2013 to November 2015, clinical data about 62 patients (78 eyes) treated with I-CXL using 0．1% riboflavin-distilled water solution were collected． Anterior segment OCT was used to examine the depth of demarcation line and they were compared between two groups at 1 month after treatment． Results The depth of demarcation line was (268．25±18．06) μm in patients treated by I-CXL using 0．1% riboflavin-sodium lactate Ringer's solution, and it was (298．95±51．97) μm in patients treated by I-CXL using 0．1% riboflavin-distilled water with statistically significant difference between two groups (t=3．594, P=0．001)． The incidences of demarcation line in the two groups were 56．3% and 83．1% respectively, and the difference was statistically significant (χ²=5．514, P=0．019)． Conclusion The efficacy of I-CXL using 0．1% riboflavindistilled water solution is better than that of I-CXL using 0．1% riboflavin-sodium lactate Ringer's solution for progressive keratoconus．