WordNet records no synonym and no antonym for legal blindness. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
vision that is 20/200 or worse in both eyes (20/200 vision is the ability to see at 20 feet what a normal eye can see at 200 feet)
Synonyms, antonyms and the broader and narrower relations for legal blindness come from Princeton University’s WordNet. Full sources and licences.