Fig 4. Estimated standardized effect sizes (β’) of age_c and age_c².

The black and grey filled circles and their 95% confidence intervals represent the standardized estimates of the effects of age_c and age_c² in the linear and quadratic regression models, respectively. The open circles represent the standardized estimates of age_c in the quadratic model and in models with additional elementary visual function predictors, i.e., near and far visual acuity measured with ETDRS charts measured at 4 m and 40 cm respectively, crowding intensity measured with LEA charts at 40 cm and contrast sensitivity represented by the Weber contrast threshold measured with a custom psychophysical task where subjects indicate which of the two figures (car or truck similar to UFOV stimuli) is currently presented. β’ = estimated standardized effect size, UFOV = Useful Field of View.