Pope Benedict XVI is nearly blind in one eye and was advised by his doctor to limit air travel because of his high blood pressure, the website Vatican Insider reported on Wednesday.
The report also said the 85-year-old pontiff often has problems sleeping and has fallen out of bed several times in recent years on foreign trips, making him tired in public appearances.
The report was based on indiscretions from papal aides that Vatican affairs specialist Marco Tosatti said he had promised to keep secret until the end of the pontificate on February 28.
"The picture is of a progressive deterioration of his health and his energy - a context that fully justifies the difficult decision that the pope has taken," Tosatti wrote after the pope said he would step down due to old age.
The report cited the pope's doctor Patrizio Polisca saying two years ago that Benedict's blood pressure was having "major jumps" and insisting that he spend "as little time as possible in a plane because of the dangers".
Tosatti added that Benedict had been expressly advised not to make the transatlantic flight to Rio de Janeiro for World Youth Day later this year.
In his report, Tosatti also said the pope could "almost no longer see" out of his left eye and therefore had to be helped up and down steps.
The report said Benedict even began using a walking stick to get around his own residence last year because his left hip and knee were hurting.
The Vatican last week revealed the pope had hit his head and bled during a trip to Mexico last year and underwent surgery three months ago to replace the batteries in a pacemaker he was fitted with while he was still a cardinal.