Pop star Justin Bieber is suffering with conjunctivitis.

The What Do You Mean? hitmaker took to Instagram on Saturday (20May17) to share a series of selfies and close-up pictures of his infected eye.

"My left eye has conjunctivitis," he wrote beside the first image.

He then zoomed in to show the swelling, even adding black and white versions for fans to compare for themselves.

"You can see it better here," Justin captioned one of the additional snaps.

It's not known how long the singer has been struggling with conjunctivitis, also known as pink eye, which causes inflammation of the membranes around the eyeball, but it appears the ailment hasn't caused him too much bother, as Justin later shared video clips of himself rocking out to Christian music group Elevation Worship's Fullness.

The 23-year-old is no stranger to the infection - he was reportedly diagnosed with the same issue in 2015.

Meanwhile, Justin has been catching up with pop culture while he recovers from the illness. He took to social media on Friday (19May17) and shared a picture of his laptop screen, on which he was streaming video footage of British singer Harry Styles taking part in U.S. late night host James Corden's popular Carpool Karaoke segment from Thursday (18May17).

"Just watched Harry styles carpool karaoke (sic)!! Hilarious!" Bieber wrote beside the shot, before revealing he is a big fan of the One Direction star's solo music. He added, "Also congrats on the album, it sounds great !"