Have severe headache only on left side and hard to focus my left eye. should i go to er?

Eye pain: need more information, when did it start, does it come and go, what are the aggravating and relieving factors, do you lose vision in that eye when the headache begins, do you throw up, has the headache woken you up from your sleep at nights. It could be Migraine, or poor visual acuity maybe you need glasses, also you need to see a neurologist. rule out increase pressure in the brain