In this paper we aimed to report a case of undetected foreign body in the right eye. A 24-year-old female applied to our clinic with the complaint of progressive loss of vision in her left eye that she had noticed for the previous five years. Visual acuity was 10/10 in her right eye and 1/10 in her left eye with Snellen charts. Slit-lamp examinations revealed a small nephelion concordant with the foreign body and a point of entry on the surface of iris of the right eye (with a visual acuity of 10/10) on biomicroscopic evaluation while a central corneal nephelion related to keratoconus was detected in left eye. Examination of fundus was normal bilaterally. This case was reported to emphasize that some intraocular foreign bodies could remain for a long period without causing reaction or impairing visual acuity.