High blood pressure , headache + double vision. checked over at a+e and given painkillers. how long approx will double vision last?

See an eye doctor: Too little information to tell. Anywhere from the time it takes to put on prism glasses if it is a 6th nerve palsy to several months or years of anti VEGF injections if you have macular edema from a retinal vein occlusion or diabetic retinopathy. If it is from high intracranial pressure due to a brain tumor.....well, you get my drift....... Go see an eye doctor ASAP.