Although it's possible that you could be having a stroke when you develop an ocular migraine it's not a sure symptom of a stroke.
When you have or are about to have a stroke you'll usually have symptoms such as losing feeling in one or both of your hands or losing sight in one eye.
However there is what is known as an Ocular Migraine stroke that can happen from an Ocular Migraine which are usually just mini strokes.