To report a case of intraocular cilium revealed by diagnostic vitrectomy in a case of stubborn uveitis that was unresponsive to steroid therapy.

A 39-year-old man was referred to our hospital due to decreased vision in his right eye that started two months prior to presentation. He had previously been treated for a diagnosis of iridocyclitis. The patient's history revealed a blunt trauma to the right eye while wearing glasses after which he developed a microhyphema and was treated for traumatic iritis at another clinic 3 months ago. He was treated with topical and oral steroids after being diagnosed with iridocyclitis and had recently been prescribed additional oral cyclosporine because his condition had not improved. Ocular examination revealed inflammatory cells in the anterior chamber and vitreous cavity with hand motion vision. Ultrasonography revealed a hazy vitreous cavity but the retina was flat. Diagnostic vitrectomy with intravitreal antibiotic injection was performed and an intraocular foreign body presumed as a cilium was detected without an entrance wound on the exterior or interior surface of the eye. After removal of the foreign body, the patient's vision was completely recovered.

In cases of chronic uveitis that do not respond to immunosuppressive treatment without a clearly definable cause, diagnostic vitrectomy should be considered, keeping in mind the possibility of intraocular foreign body.