data 5dEQ-5D-5L utility index, and the domain of physical function and pain with the SF-6D utility index. Ceiling effect of EQ-5D-5L (59%) is greater than SF-6D (22.4%). The Bland and Altman plot5D optical storage readout. (a) Birefringence measurement of the data record in three separate layers. (b) Enlarged 5×5 dots array. Pseudo colour indicated the orientation of slow axis.