Dear Student ,

You haven't mentioned about which exam you're asking for. Well, Mainly in Govt exams .. medical Fitness criteria is tested . As you have not mentioned any Govt exam name . So, as an example , I'm sharing the medical fitness criteria in Indian Railways :

There is total 7 type of medical standard .

1. A-1 : Distance Vision 6/6 without glasses
2. A-2 : Distance Vision 6/9 without glasses
3. A-3 : Distance Vision 6/9, 6/9 with or without glasses(power should not be exceed 2D)
4. B-1 : Distance Vision 6/9 ,6/12 with or without glasses(power should not be exceed 4D) [ colour vision required ]
5. B-2 : Distance Vision 6/9 , 6/12 with or without glasses(power should not be exceed 4D)
6. C-1 : Distance Vision 6/12,6/18 with or without glasses
7. C-2 : Distance Vision 6/12,NIL with or without glasses

You can check the same details from here too:

https://www.rrbchennai.gov.in/downloads/recruitment_rules/medical_standard.pdf

Hope this helps !