Hello Dr. Rynne, My Son Just Had An Unusual Sensation/occurrence

Hello Dr. Rynne, My son just had an unusual sensation/occurrence a short while ago. His job is as a A/C Tech, he's 39 years old 6ft 4inches tall and weighs around 185lbs. A short time ago he was sitting in his company truck and all of a sudden his vision went blurred and he felt dizzy and he started feeling like his eye's were starting to cross and he suddenly couldn't see for about 3 minutes. He sat in his truck and within 5 minutes or so his vision returned to normal and the dizziness went away and now he feels fine. I'm very worried about him, he rarely visits a Doctor for anything but Heart Disease does run in our family. Any help would truly be appreciated. Could this have been caused by a minor anurison?