Pagenstecher in 1883 described the first case of ophthalmia nodosa and termed the disease caterpillar hair ophthalmia. Wagenmann reported a case under the title pseudotuberculosis. Later Saemisch used the term ophthalmia nodosa.
There is an early initial stage soon after the caterpillar hairs have entered the eye in which the only symptom is the sensation of a foreign body in the eye. The patient complains of itching, burning, lacrimation and photophobia. All of these symptoms are aggravated by rubbing of the eyelids. There may be swelling of the lids, pericorneal injection and edema. On application of fluorescein, the cornea stains. The epithelium of the cornea is lost either by penetration of the caterpillar hairs or as a result of excessive rubbing of the eyelids. The discomfort is due to foreign body irritation and chemical irritation.
It has been demonstrated by Karsten that the canal of the hairs carries formic acid