Byrson, competing for Great Britain, finished 24th in her qualifying pool in the Egyptian capital on Wednesday.
It meant the Plymouth University medical student, like the rest of the British women, missed out on reaching Friday’s final.
Bryson made a tough start to the competition with a 2:32 minute swim before improving her position by winning 14 of her fencing bouts.
However, the gap between herself and a qualifying place was too big going into the laser-run. She did improve four places in that event but still missed out.
Afterwards she said: “Not the day I was hoping for with a poor fence and swim but it’s still early in the season and I’m taking everything at this level as experience. Thanks to everyone who supports me as it makes all the difference. On to the next comp.”