British sprinter Libby Clegg says she faces a "challenging time" after being told she must wear a blindfold while competing at the Rio Paralympics.
Clegg, 26, has a deteriorating eye condition, which has led to her reclassification from T12 to T11.
The ruling means the London 2012 T12 100m silver medallist will now race against Brazil's three-time Paralympic champion Terezinha Guilhermina in Rio.
Clegg will race in Saturday's T11/T12 200m at the London Anniversary Games.
Clegg, who has Stargardt's Macular Dystrophy and is registered blind, said: "I've never come out of blocks blindfolded. It's absolutely terrifying for me.
"Being blindfolded, your hearing is much more acute and things do sound a lot closer than they are."
In 2015, Clegg ended her five-year association with guide Mikail Huggins, with whom she won Commonwealth Games gold in Glasgow in 2014, and she will run with new partner Chris Clark in Rio.
Clegg lost her funding from UK Athletics for 2015-16 after pulling out of last year's IPC World Championships because of a foot injury.
The BBC has live TV, radio and online coverage on Friday and Saturday of the London Anniversary Games at the Olympic Stadium in Stratford.