Table 4.

Sensitivity analysis (mean differences) for the primary and secondary outcomes in randomized clinical trials assessing corneal collagen cross-linking (epi-on vs. epi-off)

Subgroup	MD	95% CI	P
Kmax flattening (D)
Low risk of bias	− 1.69	− 2.62 – − 0.76	0.004*
With iontophoresis	− 0.50	− 3.67 – 2.67	0.757
UDVA (logMAR)
Low risk of bias	− 0.05	− 0.20 – 0.10	0.491
With iontophoresis	− 0.01	− 0.23 – 0.21	0.930
CDVA (logMAR)
Low risk of bias	0.06	− 0.004 – 0.118	0.069
With iontophoresis	0.05	− 0.01 – 0.11	0.127
CCT (μm)
Low risk of bias	− 2.0	− 18.38 – 14.38	0.811
With iontophoresis	− 4.76	− 14.53 – 5.02	0.340
ECD (cells/mm2)
Low risk of bias	− 48.82	− 180.79 – 83.15	0.468
With iontophoresis	3.0	− 22.86 – 28.86	0.820

CCT central corneal thickness; CDVA corrected distance visual acuity; CI confidence interval; D diopter; ECD endothelial cell density; logMAR logarithm of the minimum angle of resolution; MD mean differences; UDVA uncorrected distance visual acuity

All the results were obtained through fixed-effects models because we only had two studies to summarize. If the value of the summary effect is negative, epi-on corneal collagen cross-linking would have more mean differences. Otherwise, epi-off would have this condition

*indicates statistical significance