Loss of vision associated with pain, redness, watering and exacerbated by bright lights usually indicates inflammation or infection of the cornea (keratitis) or within the eye (iritis or, especially if following surgery inside the eye, endophthalmitis).
Smeared vision where the eyes are sore or gritty may be due to underlying poor tear films (dry eye)
Unilateral loss where there is pain on moving the eye suggests optic neuritis.
Unilateral loss with deep pain, redness and nausea or vomiting is seen with acute glaucoma.
Bilateral loss of vision, often with zig-zag lines or lights, together with or followed by headache is usually due to migraine.
