Periocular skin “tattooing” caused by gel pen pigment mistaken for periorbital bruising: a case of missed diagnosis of traumatic intraorbital pen core foreign body - Chao Xiong; Zhang-Jun Ren; Xue-Mei Li; Jin-Hai Yu; Yue Li; Yun-Xiu Chen; Qi Jin; Ze-Xi Sang; Si-Yi Wang; An-An Wang; Pu-Ying Gan; Qi-Hua Xu; et al. (International Journal of Ophthalmology)