Supplementary Material for: Prolonged Button Battery Exposure Leading to Severe Ocular Injury Without Heavy Metal Poisoning

Introduction Prolonged exposure to a complete button battery can cause severe tissue necrosis in the eye and permanent impairment of visual function. The main mechanism of injury is the current generated by the hydrolysis of tissue fluid at the negative electrode and the production of hydroxide ions. Case Presentation A 3-year-old girl，went to the local hospital because of swelling and pain in her right eye of 12 hours’ duration. The local doctor performed an orbital CT（Computer Tomography）scan and found a foreign body between the right eyelid and the eyeball. The foreign body was removed immediately under general anesthesia. And it was found that the foreign body was a button battery, but it prolonged 39 hours from the onset of the child’s symptoms. The child underwent a second operation in our hospital and receiving amniotic membrane transplantation combined with conjunctival flap coverage. Topical corticosteroid and antibiotic eye ointment was continue for 3 months after surgery. Local Pigmentation was seen, no symblepharon, but the cornea was still opaque and the visual acuity was only FC（Finger Count）. In this particular case, heavy metal testing conducted on the child's blood fortunately revealed that the levels were within the normal range. Conclusion Early detection and urgent removal of button battery is crucial in order to minimise exposure time. We should also be concerned about heavy metals in the blood.Children should be kept away from button batteries as much as possible to avoid such injury