Eye<unk> ness is due to swollen or dilated blood vessels, which cause the surface of the eye to look<unk> , or bloodshot.
There are many possible causes of a<unk>  or eyes. Some are cause for concern; some are medical emergencies.  Others are nothing to worry about.
How<unk>  the eye appears is often less of a concern than whether you also have eye pain or difficulty seeing.
Red eye
Mind's eye
Black eye
Blue sclera
Exophthalmos
Buphthalmos
Dry eyes
Lagophthalmos