Redness occurs when the blood vessels in the white of the eye, the sclera, expand. If the redness occurs in small localised areas, or spots, this is probably due to an injury. If the whole of the sclera appears reddened this might be caused by infection, allergy, glaucoma or simply tiredness.

Treatment for the red eye depends on what caused it in the first place, so if the redness doesn't resolve itself, consult your optician or GP as soon as possible.

If you wear contact lenses and you suspect a mild redness in your eyes might be due to being in a smoky or dry environment, you can try eye drops for immediate relief. If this doesn't work or if the redness is more severe, remove your contact lenses immediately and contact your optician.