@Pe ***
. Good question.
Not necessarily. Here’s why:
1. It’s functional, not clinical – Thailand uses a “three colours discrimination test,” not the Ishihara book. They care if you can tell red/yellow/green traffic lights apart, not if you have perfect color vision.
2. Many color-deficient people pass – Expats report passing despite being “Strong Protan”. One person wrote: “when driving I have absolutely no trouble distinguishing red / yellow (amber) / green traffic lights… and I have never had any trouble with colours when driving” and he got his Thai license.
3. Where it gets tricky: The peripheral test. You have to ID red vs green lights in your side vision without looking directly. A colorblind applicant said: “THIS WILL BE VERY DIFFICULT IF YOU ARE COLOUR-BLIND! … I struggled to see the red (it didn’t seem very bright to me)”.
4. It varies by office – Some test centers skip parts, some are stricter. Some use a chart, others use traffic lights.