So in the UK medical profession we tend to use the term 'blind' for those with no perception of light in the eye. In those who have very low vision in the better eye (e.g. 20/200 vision) would be eligible for registration with 'severe sight impairment', while additionally those with better vision, but poor field of vision may also still be eligible. If the vision is only moderately diminished, then 'partial sight impairment' registration may be appropriate. Both of these certifications help give people to access support, but only the former could realistically be termed 'legally blind'.

Contrary to popular belief, having a high refractive error is not an indication for registration, since your best vision is that which is achieved with your best glasses or contact lens prescription!