It has been demonstrated by Karsten that the canal of the hairs carries formic acid [jamanetwork.com]

71 %) Cicatricial Pemphigoid (71 %) ( Benign Mucosal Pemphigoid, Benign Mucous Membrane Pemphigoid, Ocular Pemphigus, Scarring Pemphigoid,) Primary Inoculation Tuberculosis (71 %) ( Cutaneous Primary Complex, Primary Tuberculous Complex, Tuberculous Chancre [gulfdoctor.net]

Conjunctival nodules on histopathological examination showed a granulomatous reaction around the hair shafts. [healio.com]

There was a conjunctival nodule in two eyes (6.8%). Resolution of symptoms occurred in 3-21 days. Treatment included topical steroids, cycloplegia, and removal of hairs with forceps. [ncbi.nlm.nih.gov]

These include catarrhal conjunctivitis, keratoconjunctivitis, conjunctival nodules, keratitis, iridocyclitis, iris nodules, vitritis, papillitis, or chorioretinopathy. [omicsonline.org]

Fundoscopy showed an area of inactive chorio-retinal lesion in the peripheral retina, with no evidence of vitritis. He was started on topical steroid treatment and responded well. Treatment is continuing. He remained completely symptom-free. [nature.com]