Go see a neuro-opthomologist. They can run tests on the eyes, not on the head.
Try wearing sunglasses more to cut the sensitivity to light.
You don't mention your occupation. Welders at my workplace often make similar complaints, even with state-of-the-art eye filters. Do you spend a lot of time in the sun without eyeshades?
I have a blank spot in my vision which isn't visible when my retina is checked, and it's not the blind spot caused by the optic nerve. When I close my eyes a faint spot appears after a few minutes. It's annoying but the vision from the other eye fills in the gap.
Thank you for your question. Without being able to examine your eyes it is quite difficult to say exactly what is causing blurred vision here and why you seeing flashes or black floaters around field of vision. However, this usually occur with diabetic retinopathy, trauma, retinal detachment or cataract which causes gradual reduction in vision, seeing halos around lights or seeing things double with the eyes and susceptibility to bright lights and glare. Even then I would suggest that you discuss this with your doctor, who can examine your eye and refer you to an ophthalmologist for a second opinion. Hope this helps.