At the Paralympics, there are three broad areas of classification with many subcategories within each broad area.
These broad areas classify athletes as physically disabled, intellectually disabled or having low vision/blindness.
Vision Australia orthoptist Cem Oztan has been involved in sports classification for athletes who are blind or have low vision for more than 10 years.
"Three main categories are used to classify athletes who are blind or have low vision," Cem explained.
"These classifications group athletes with similar levels of vision where the competition is decided on sports ability rather than the level of vision having an impact on the outcome of the event."
The three main classifications for athletes who are blind or have low vision are:
- B1 – These athletes can have no light perception, light perception or are able to see very vague hand movements.
- B2 – These athletes can see large letters on a vision chart at two metres or have a visual field of less than 10 degrees.
- B3 – These athletes can see large letters on a vision chart at three to six metres and have a visual field up to 40 degrees.
"The classification process is similar to a standard vision test," Cem said.
"The process isn't perfect though because the conditions the athletes are tested and classified under are not the same kind of conditions they might compete in so their vision can be different.
"As with anyone who is blind or has low vision, an athlete's vision might vary in different settings like inside and outside because of light, brightness and sun glare or changes from day to night.
"While the process of classification isn't perfect, I am glad stricter rules around classification have been brought in in recent years.
"Before the rules around classification were as strict, there were dishonest people, not just athletes but coaches and other officials as well, who would try to cheat the system by putting the athlete in a more severe vision classification than their actual vision to use their vision as an advantage and give them a better chance of winning."
While the B1-3 classifications are the standard for classifying athletes who are blind or have low vision, each sport also gives athletes another classification for their particular event.
Read this vision classification factsheet from Paralympics Australia (external website) for a breakdown of the criteria athletes who are blind or have low vision meet in their chosen discipline.