Repeatability of Subjective Refraction in Different Age Groups

Background: The purpose of this study was to assess the inter-examiner repeatability of subjective refraction across diverse age cohorts, an aspect not previously investigated. Methods: A cross-sectional, randomized study enrolled 86 participants (mean age: 37.0 +/- 18.0 years), distributed into three groups: youth, non-presbyopic adults, and presbyopic adults. Each participant underwent three subjective refractions by three different optometrists on separate days. Repeatability analysis encompassed all refractive variables (M, J0, and J45). Results: There were no significant differences between optometrists in all refractive variables for either the overall sample or across age groups (p >= 0.05). Additionally, no correlation was found between participants' age and the mean difference in refractive variables across optometrists (p >= 0.05). The 95% confidence interval of repeatability (r) for the total sample was +/- 0.70 D for M, +/- 0.29 for J0, and +/- 0.21 D for J45. Conclusions: Based on these findings and previous research, it is suggested to establish 95% limits of agreement of +/- 0.75 D for M, and between +/- 0.25 D and +/- 0.50 D for both J0 and J45 when validating new refraction systems compared to subjective refraction as the gold standard, regardless of the age of the subjects evaluated.