## 2 Materials and Methods
### Environment Conditions and Testing Procedures  
Both the Ishihara Test and the Farnsworth-Munsell 100-Hue Test were evaluated under controlled lighting and geometric conditions. The instructions outlined in the FarnsworthMunsell 100-Hue Test manual [40] and the recommendations specified in ISO 23603 [53] were strictly followed in all testing procedures.  
The laboratory setting featured a windowless environment devoid of uncontrolled light sources. A VeriVide VL120 lighting screen (VeriVide Limited, Leicester, UK) served as the illuminant for conducting the tests. This screen was equipped with D65 light sources, boasting a colour temperature of 6500 K and a Colour Rendering Index > 95. D65 lighting mimics the spectral energy distribution of average daylight.  
The lighting screen measured 1335 mm \(\times\) 740 mm, covering the entirety of the working field. Photometric conditions, specifically illuminance, were meticulously measured, recorded, and adjusted in accordance with the technical usage guide of the Illuminometer Model 5200 (Kyoritsu Electrical Instruments Works, Ltd., Tokyo, Japan). The lighting level remained consistently between 1250 lx and 1320 lx across the working area throughout the testing process. Surrounding and ambient conditions were meticulously maintained to meet specifications, with all adjacent walls painted in a neutral grey equivalent to Munsell N5-N7.  
To ensure optimal standardisation, the lighting screen was positioned 80 cm (32'') above the viewing surface, parallel to it (creating an illumination angle of 90 deg). The working area was centrally located on the lighting screen and covered with a matte black surface to eliminate any reflections.  
For test execution, subjects were seated on a rigid grey chair that provided an optimal distance of approximately 50 cm between their eyes and the Farnsworth-Munsell Test. This setup ensured an ideal viewing angle of the colour samples.  
All subjects underwent testing on the same date in March, within the time interval of 15:00-18:00, in Spain (Europe). An anonymised questionnaire was simultaneously distributed to collect the required data and test results.  
In order to minimise performance bias, the same testing protocol described in the studies with which the obtained results will be compared has been followed, along with the recommendations specified in international standards.  
The testing sequence commenced with the administration of [PERSON]'s Tests for Colour Deficiency 32 Plates Edition. Subjects were seated in a chair and positioned the book approximately 80 cm from their eyes. They verbally communicated the result for each plate, which was then recorded by an assistant. Following this, subjects proceeded to undertake the online Ishihara Test, with self-recording of results in the questionnaire.  
A 10-min interval, during which subjects refrained from viewing screens or coloured surfaces, was observed after the completion of the online test. Subsequently, subjects were prepared for the Farnsworth-Munsell 100 Hue Test. The four boxes containing unordered chips on the top and fixed samples on the bottom were opened. Subjects arranged the chips without a time constraint and recorded the result for each box in the questionnaire.  
The data (caps order) recorded for each test were input into the Farnsworth-Munsell 100 Hue Test Scoring Software (unique version) developed by Munsell Colour Services Laboratory (Greatmaccheth, New York, NY, USA). Data entry included cap order, subject gender, illumination type (D65), location (Europe), job function, and industry (unspecified). The software provided results such as Total Error Score (TES), Square Root of Total Error Score (\(\surd\)TES), classification as Low, Average, or Superior discriminators, and a scoring plot available in polar and linear styles. All results could be exported as.pdf or.csv files.