Simplify the following text for a Grade 12 native English-speaking person.
Original: Athletes without a disability also compete at the Paralympics : The sighted guides for athletes with a visual impairment , are such a close and essential part of the competition , that the athlete with visual impairment and the guide are considered a team , and both athletes are medal candidates .
Simplified: The Paralympics recognizes three different grades of visual impairment , consequently all competitors in goalball must wear a visor or `` black out mask '' so that athletes with less visual impairment will not have an advantage . Other sports , like athletics , are open to athletes with a wide variety of impairments .