Very Challenging Cases to Diagnose: Concealed Foreign Bodies in the Upper Palpebral Conjunctiva Should Always Be Kept in Mind in Unresolved, Long-Lasting Chronic Ocular Pain

Ocular pain is a common complaint, and anything that stimulates the sensory nerve terminals innervating the eye, the peripheral axons of neurons located in the trigeminal ganglion, can cause it. An undetected ocular foreign body sometimes masquerades as a common condition such as dry eye or other frequencies, which can misguide both the doctor and the patient into an endless cycle of ineffective therapies and incomplete diagnoses. In recent years, as the concept of neuropathic pain has become more widely recognized, cases of idiopathic ocular pain in which the actual cause of the discomfort is a foreign body seem to be increasingly misdiagnosed as neuropathy. This report reviews cases in which hidden foreign bodies were responsible for unresolved, long-lasting chronic ocular pain. All records referencing the phrase “foreign body removal” were extracted from the outpatient clinic notes recorded by the author (H.T.) between 2016 and 2018 at Ashikaga Red Cross Hospital using the search engine of the computerized record system. There were 3 cases that were very difficult to diagnose: (1) a very minute iron shard in a 72-year-old female cataract surgery patient, (2) a deeply hidden eyelash in a 60-year-old female with varicella-zoster virus-related keratoconjunctivitis, and (3) an extremely small grain of sand in an 83-year-old female diagnosed with dry eye. In all cases, the foreign body was detected in an area of the upper palpebral conjunctiva without typical pathognomonic signs. Removing the foreign bodies led to immediate and dramatic relief of long-lasting, previously unresolved chronic ocular pain.