A group of British athletes have called for changes to the International Blind Sport Federation's (IBSA) "discriminatory" classification rules, which prevent athletes in the B4 category from competing at events.
The B4 classification is recognised by British Blind Sport but not the IBSA, leaving a number of visually impaired athletes who fall into the category unable to participate at international competitions.
A petition backed by the likes of British goalball player Adam Knott, who represented the host nation at the 2012 Paralympic Games in London, claims the current system "discriminates against B4 classified athletes".
The petition, signed by more than 4,000 people at the time of writing, calls on the IBSA and the International Paralympic Committee to "outline their plans on resolving the discrimination issues within the current system, and therefore reconsidering the eligibility of B4 athletes and their involvement in International blind sport."
A three-stage classification for blind sport is used at international level, which ranges from B1 to B3.
Blind sports apply a three-stage classification at international level, ranging from B1 to B3.
B1 athletes are entirely, or almost entirely, blind, while the B3 category includes people who can see at six metres what a fully sighted person could see at 60 metres.
People who see at six metres what the fully sighted could see at 24 metres are included in the B4 category.
Those classified as B4 would be able to register as sight-impaired in the UK.
"I honestly don’t know why the cut off is where it is," British Blind Sport vice-chairman Dave Gavrilovic told The Guardian newspaper.
"Sight classification is a very delicate subject and has to be dealt with very carefully.
"We have no objection to the idea [of reclassification] but it needs proper research."
insidethegames has contacted the IBSA for comment.