When i laugh , everything starts to go black. this started about 1 year ago.prior to then i had not experienced this . i am 53 years old?

Laugh Syncope: It is possible that you have "Laugh Syncope" which is a form of passing out or almost passing out while laughing. Laughing increases chest pressure and can temporarily slow the blood flow returning to the heart. The blood pressure then drops, causing dizziness or unconsciousness. See your doctor for an evaluation. More info: https://en.wikipedia.org/wiki/Laughter-induced_syncope