Changes in the area of accurate vision of the retina can reduce colour vision and contrast definition. Swelling or bleeding in the centre of the retina can impair your reading vision quickly, sometimes as a matter of days or even hours. Swelling is often linked to image distortions, which impair your ability to see things near you or see things clearly.
In severe retinopathy, new blood vessels may grow in the back surfaces of the eyes and bleed into the vitreous body inside the eye. You can sense the vitreous haemorrhage as a soot rain, moving opacity in your field of vision, a ragged field of vision or weakened eyesight of different degrees. Blacked-out vision or a significant lack of visual field may be signs of dense vitreous haemorrhage or a detached retina.
The strong eye pain related to severe retinopathy can be a sign of increased pressure inside the eye resulting from the growth of new blood vessels. However, it is quite rare these days.