Hi have had temporary vision loss on one eye that comes out of no where it can last about 5 minutes and its black patches in my vision it can be half my vision or just patches. an eye test has ruled out no issues with my eyes so what could it be?

This sounds most consistent with a migraine or equivalent. But since migraines are a diagnosis of exclusion, meaning you've ruled out other causes, I would suggest evaluation with an ophthalomologist first and then consultation with an internist or neurologist once you've ruled out ocular causes.

You may intermittent loss of blood flow to the eye Check for: patent foramen ovale With small platelet thrombi Get a echocardiogram with bubble technique Check a CT angiogram of the neck. And brain to review blood flow in carotid and vertebral arteries Take aspirin and a statin( like Lipitor)

It is not feasible to provide an exact diagnosis in absence of a complete evaluation. Assuming no ocular or retinal abnormalities, might wonder about vascular problem such as a focal arterial dissection or primary cardiac issue, but the more common etiology is classical migraine aura ("ocular migraine", but would involve BOTH eyes). Evaluation by a neurologist would be next step.