A month before Wrestle Kingdom, Naito had surgery on his right eye. Naito admitted to having vision issues in May of last year when he was seeing double in the ring. In October, he was seeing triple in the ring. One of the muscles supporting the eye was paralyzed and he "couldn't focus his vision with both eyes open." He was seriously thinking of retirement.
NJPW double champion Tetsuya Naito described the eye issues he dealt with throughout 2019 that he thought might force him into retirement.