Objective To evaluate the differences of the thinnest-point corneal thickness (TCT) decrease after three different corneal crosslinking (CXL) protocols for progressive keratoconus.Methyds Retrospective clinical case study.From August 2010 to November 2015,consecutive 85 patients (110 eyes) with progressive keratoconus were enrolled and treated with CXL in Department of Opthalmology,Navy General Hospital.21 patients of 25 eyes underwent standard epithelium-off corneal crosslinking (S-CXL),14 patients of 22 eyes underwent 1 g · L-1 riboflavin-sodium lactate Ringer's solution iontophoresis-assisted CXL (I-CXLa),and 50 patients of 63 eyes underwent 0.1％ riboflavin-distilled water solution I-CXLb.Preoperative and postoperative TCT were measured by ALLEGRO oculyzer.The differences of TCT decrease after treatment were compared among the three CXL protocols.Results The differences of TCT from baseline after 3 months,6 months and 12 months in the S-CXL group were (-14.93 ±27.16) μm,(-31.94 ±22.89) μm,(-27.71 ±26.01) μm,respectively,the I-CXLa group were (-20.14 ± 19.09) μm,(-10.10 ± 24.28) μm,(-7.11 ± 22.26)μm,respectively,the I-CXLb group were (-28.08 ± 26.14) μm,(-21.08 ± 25.62) μm,(-15.91 ± 19.19)μm,respectively.Three months after treatment,the differences of TCT decrease in the three groups was not statistically significant (P =0.188);Six and 12 months after treatment,the differences between S-CXL and I-CXLa were statistically significant (all P ＜0.05),but the differences between S-CXL and I-CXLb,between I-CXLb and I-CXLa showed no significant difference (all P ＞ 0.05).Conclusion Six and 12 months after treatment,TCT decrease is related to the CXL protocol.TCT decrease degree may reflect the intensity of crossinking.TCT decrease in I-CXLb is smaller than that in S-CXL,but there is no statistical difference.