Figure 1.

Stereo-pair scatter plot of symmetric dioptric power space (A) using coordinate vector h for the Near Eye Tool for Refractive Assessment (NETRA) refractive states for the right eyes of 279 participants, aged 9 to 63 years with a 95% surface of constant probability density (SCPD). The NETRA is a mobile phone-based method to measure refractive behaviour. Readers should fixate to an imaginary point beyond the figure to see the stereo-pair with an exo-posture, (B) The same sample but using power matrices (F _i ), (C) the same sample but with axes rotated to look along the scalar axis (label ${\displaystyle 5\mathbf{I}}$ is obscured by data) to directly view the antiscalar plane, (D) Two pseudo-three-dimension plots using coordinate vector f to produce a stereo-pair for the same sample but without the SCPD. (Data courtesy of NH—see reference number ⁶⁴).