Some causes of loss of vision in the left eye are optic neuritis, retinal detachment and transient ischemic attack, according to Mayo Clinic. Another possible cause is an eye occlusion, notes All About Vision.
Eye occlusions are also known as eye blockages or eye strokes, explains All About Vision. Like strokes in other parts of the body, eye strokes occur when blockages within veins and arteries block the flow of blood to vital structures (such as the retina and the optic nerve in this case). Optic neuritis is an inflammation of the optic nerve, commonly causing pain and temporary vision loss, reports Mayo Clinic. Retinal detachment is a accompanied by symptoms such as a large number of floaters and flashes of light in the affected eye, and it is a medical emergency that can result in a permanent loss of vision if not treated in time, warns Mayo Clinic.