My Son Was Born With One Pupil Enlarged. He Is

My son was born with one pupil enlarged. He is 24 yrs now. The doctor originally told me that he should wear a medic-alert band for his condition, otherwise, if he were unconscious, medical personnel might think his brain was swelling. I can no longer remember the name for the condition. Something like "Addais Pupil". Could you please refresh my memory as I finally want to get him that bracelet.