A blood vessel blockage at the back of the eye can cause fogginess.
In rare cases, fogginess can be caused by a brain tumour pressing against the back of the eye, or optic neuritis - inflammation of the optic nerve.
The symptoms include washed-out colours and loss of contrast.
If the rip is at the top, with gravity, the retina can be pulled off in less than 24 hours; with a rip at the bottom, that process can take weeks.
'The main symptom of detachment is a large blank area in your vision that won't go away, which may be associated with flashing lights or a general fuzziness.
'These flashing lights look like cracked glass or water running down over sparkling lights.' 'Once the flashing lights start you can prevent a fullblown migraine by taking painkillers, drinking water, upping your blood sugar with food and laying down in a quiet, dark room,' says Mr Constantine-Smith.