Fig. 5

Comparison of blood flow velocity (BFV) among soft contact lens (CL) studies using the same imaging protocol. Chen et al. examined the BFVs of 22 NCL wearers after 6 h of CL wear and found a significant increase in BFVs. Shi et al. examined 20 HCL wearers who were imaged when they were not wearing their CLs after one night of sleep and found that BFV remained higher compared with that of 40 NCL wearers. In the Hu et al. study, a significantly higher BFV was observed in 75 HCL wearers than in 91 NCL wearers. Comparing BFVs of HCL wearers in the Hu et al. study with those of NCLs after 6 h of CL wear and with those of HCLs when they were not wearing their CLs, no significant differences were found. Overall, it appeared that wearing lenses caused an elevated BFV, and a possible ceiling effect limited the evaluation within a modulated range [33]