sudden blindness
Refers to the condition of suddenly losing one's sight. The term is now considered sensitive and is rarely used; modern medical or descriptive language would use other expressions.
The term 俄盲 appears in old documents, but it is now considered discriminatory.
person suddenly blinded
Refers to a person who has suddenly lost their sight. Like sense 1, this usage is sensitive and largely obsolete; modern Japanese would use more respectful phrasing.
The term 俄盲 should not be used nowadays.