Coloured Haloes Around Lights
This is a symptom complained of by patients in a number of eye conditions. Haloes are coloured rings seen around artificial lights with the rings red outside and blue inside. The common conditions in which haloes are seen are glaucoma, cataract and conjunctivitis. Less frequently they are seen in cases of corneal scar, drug reactions, simply an oily spectacle lens and too much exposure to glare on water or snow.
Haloes should always be taken as a sign of glaucoma until proved otherwise and the eye doctor should be consulted at the earliest convenience.
Floating Spots or Floaters
There are fine spots or filaments seen when viewed against a bright illuminated background (such as a blue sky). Though they may appear suddenly, an isolated floater with no history of flashing lights is seen often even in normal, eyes and is harmless, though a source of disturbance to a sensitive patient. The floater usually moves in the same direction as the person looks, and can be quite irritating. Usually these floaters are due to blood or tissue cells which have escaped into the vitreous and unless they interfere with vision no treatment is required.
However, a stream of floaters suddenly appearing, with or without flashes of light, in a myopic eye, should be immediately seen by a doctor to eliminate any risk of an impending retinal detachment.
Flashes of Light
Flashes of light occurring in any section or quadrant of the eye are always to be taken seriously unless proved otherwise.
Flashes occur because of an irritation to the retinal area. They may indicate the onset of a retinal detachment or the presence of an inflammation in the retinal area (choroiditis).
An occasional flash of light is seen after a head injury or following a severe bout of coughing or vomiting and is usually not significant. However it is a lot safer, especially if the flashes persist, to immediately visit your eye doctor who will dilate the pupil and have a detailed look at the retina.
Rarer causes of flashes are the onset of migraine or a lesion (a disease process) in the back part of the brain, the occipital or visual cortex.