Traumatic cataract with corneal scar in a patients right eye. A cataract is an opacity in the lens of the eye that results in blurred vision. Unless the lens is replaced, a cataract can eventually cause loss of vision. Cataracts are most commonly due to ageing, but can also be caused by blunt trauma (injury) to the lens. The same injury may have caused the scarring on the cornea, the transparent front part of the eye.