_:vb50956673 . _:vb50956673 . _:vb50956673 "url:http://ghr.nlm.nih.gov/glossary=nystagmus"^^ . _:vb50956673 . _:vb50956673 "A pathologic nystagmus, present at birth, characterized by involuntary, rhythmic eye movements; oscillations are usually horizontal in direction."^^ . _:vb50956673 . _:vb50956673 "url:http://en.wikipedia.org/wiki/Nystagmus"^^ . _:vb50956673 "url:http://www.merckmanuals.com/professional/ear_nose_and_throat_disorders/approach_to_the_patient_with_ear_problems/evaluation_of_ear_disorders.html#v942669"^^ . _:vb50956673 . _:vb50956673 .