Subjective Peripheral Refraction Using a Gabor-Based Duochrome Test in Young Adults: An Exploratory Study

Background/Objectives: Subjective methods may complement objective measurements when investigating peripheral optical correction. This exploratory study assessed whether a Gabor-based duochrome test could yield spherical endpoints at multiple retinal loci and examined their association with central refractive status. Methods: Thirty-five young adults viewed simultaneously presented red and green Gabor stimuli at 12.4° eccentricity in the left eye while wearing full central distance correction. The spherical addition producing equal perceived clarity was recorded at seven retinal loci. Groups were defined by central spherical equivalent refraction (SE): lower myopia, SE < −5.00 D (n = 22); higher myopia, SE ≥ −5.00 D (n = 13). Group comparisons and correlations used multiplicity adjustment and sensitivity analyses. Results: Endpoints were available for 234/245 planned participant–locus measurements (95.5%). Mean additions were larger in the higher-myopia group at every locus. At the superior retinal locus, means were +0.81 and −0.06 D, respectively (difference, +0.865 D; Bonferroni-adjusted p = 0.044). The group-by-locus interaction was not statistically significant (p = 0.119), and the superior-locus comparison was sensitive to sample composition and model specification. Greater myopia magnitude was positively correlated with superior-locus spherical addition (Spearman ρ = +0.475; unadjusted p = 0.0039), meeting the seven-test Bonferroni significance threshold (adjusted p = 0.0273). Conclusions: Peripheral duochrome endpoints were available for most planned measurements. Refractive-group differences were exploratory and did not establish a selective superior-retinal effect. Repeatability, agreement with objective peripheral refraction, and visual benefit require evaluation before clinical application.