Colour discrimination in post-COVID-19 observers assessed by the Farnsworth-Munsell 100-Hue test

Post-COVID-19, recorded were various ophthalmological symptoms and visual impairment. We hypothesised that colour vision may be affected too. We assessed colour discrimination using the Farnsworth-Munsell 100 Hue test (FM-100) in individuals, who have had COVID-19 (N=77; 18–68 years).The following supporting information can be downloaded at: https://figshare.com/s/6900f26033c71afc7888. Data analysed in this study. Appendix 1: Error distribution in the FM-100 diagram for post-COVID participants (N=77). Appendix 2: Computer program for calculating major and minor axes for the D-15, D-15d and FM 100-Hue tests.Supplementary Materials: Table S1 – Demographic characteristics of post-COVID participants, and self-reported duration of the illness and symptoms.Table S2 – FM-100 parameters for post-COVID participants: total error score (TES), error scores for four FM-100 boxes (AES, BES, CES, DES), and partial error scores (PES) for the specified hue bands, B-Y and R-G axes, and hemispheres of the FM-100 diagram: left (caps 1–43), right (caps 44–85), upper (caps 27–70) and lower (caps71–26). Figure S1 – FM-100 scores (ÖTES) for individual post-COVID participants as a function of age. For comparison, plotted are mean ÖTES scores for each age group of normal trichromats27,29,30, as presented in Table 1. Numbers accompanying points correspond to IDs of post-COVID participants, whose values exceed the lowest normal trichromats’ mean. Table S3 – Spearman's correlation coefficient (р) between √PES in different hue bands and the number of days elapsed after the recovery of post-COVID participants. Figure S2 – √PES for post-COVID participants in different hemispheres of the FM-100 diagram: (a) √PES in left and right hemispheres; (b) √PES in upper and lower hemispheres; (c) √G–B – √R–Y difference (lower vs. upper hemisphere) as a function of the time elapsed after the participants’ recovery. Zero difference is indicated by a solid horizontal line. Colour-coded are participants’ age groups. Table S4 – The Vingrys and King-Smith indices of moment of inertia. Highlighted are values exceeding the cut-off values for normal trichromats, C-index >1.12 and S-index >1.38, and negative Angles, indicators of a tritan defect. Table S5 – Descriptive statistics of FM-100 indices for post-COVID participants (N=5) with negative Angle in comparison with mean values for 72 participants with positive Angle stratified as two groups in accord with the severity C-index cut-off value, C=1.12. Table S6 – Clusters of post-COVID participants based on their FM-100 performance, TES and the three parameters of moment of inertia35, obtained using the hierarchical clustering method. In each cluster, participants’ IDs are given in colour, as coded in Figure 6. Highlighted (in grey) are individual participants’ indices that assume an acquired (mild) colour vision deficiency: TES>90th percentile, C-index and S-index exceeding the cut-off values, negative and relatively low positive Angle.