Taking to his Instagram stories to update fans on his medical trouble, Fletcher uploaded a number of pictures showing a swollen eye as he sat in hospital.
In a caption on one of the pictures, Fletcher revealed what he was suffering from: "I've literally been asleep all day. Just woken up.
"Third time I've had Uveitis and each time it's wiped me out like this."
He later offered an update to fans: "Home. Another 6 weeks of steroid eye drops here we go."
Fletcher also suffered with the condition shortly before Christmas, saying at the time: "Sorry I've been quiet for a bit. I was wiped out with some sort of illness and in bed for a few days. I just got back on my feet yesterday and uveitis decided to kick me down again."
According to the NHS, uveitis is inflammation of the middle layer of the eye which can cause eye pain and changes in vision. Most cases are a result of an issue with the immune system and are usually treated with steroids.
It can develop into complications such as glaucoma and cataracts.
McFly are currently set to tour the UK later this year, kicking off in Wolverhampton in June before going on to play places such as Leeds, Margate and Tunbridge Wells.
They will also perform at the touring Pub in the Park festival alongside other acts such as Sam Ryder, The Jacksons, Ronan Keating and the reunited Sugababes.
The band's seventh album will also be released on 9 June and entitled Power to Play. It's their first album since 2020's Young Dumb Things which was their highest charting album since 2005's Wonderland.
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