The Sword Sovereign Zhiyuan indeed had an affliction in his right eye.
Ten years ago, Zhiyuan and Shang Zhijun went out to escort disciples during their training. Shang Zhijun accidentally entered a forbidden area belonging to a divine beast, enraging the ancient creature.
To save Shang Zhijun, Zhiyuan was burned in the right eye by the Vermillion Bird divine beast. It had not healed to this day, and his vision was significantly affected.