[Processionary (Thaumetopoea pityocampa Schiff) induced ocular lesions: case reports]

The Processionary (Thaumetopoea pityocampa Schiff), is an endemic insect of pine and cedar trees, existing both in rural and urban areas. Ocular toxicity, once rare due to the efficacy of eradication methods, is caused by the insects' hair and is expected to be more frequent with its recrudescence. We report two clinical cases and review the epidemiology of Processionary and its eye injuries. Case 1: a 64 year-old patient complained of red eye and foreign body sensation after being gardening. She had a BCVA of 0.5 and biomicroscopy revealed an epithelial erosion, flare (++), Tyndall (+++) and the presence of a setae in the deep corneal stroma. Case 2: a 28 year-old patient complained of severe pain in the right eye and hyperemia after having had contact with a caterpillar. He presented with a BCVA of 0.6, Tyndall (+++) and multiple filaments (over 20) at different depths in the cornea. Case 3: a 23 year-old patient refers to the ER with foreign body sensation and constant lacrimation in the right eye after having been completing military exercises in an urban park. He presented a BCVA of 0.3, multiple epithelial erosions in the nasal half of the cornea that cove-red multiple orange strands and an anterior chamber reaction (Tyndall +). Therapy was initiated with topical steroids and symptomatic surveillance. Ocular toxicity due to Processionary hairs, whose movement occurs preferentially towards the posterior pole, includes early signs (conjunctivitis, keratitis, and uveitis) and late signs (cataract, pars planitis, vitritis, and retinitis). The 3 cases presented had early lesions, having fully recovered from the inflammatory condition after 6 months. However, inactive setae were still visible in the corneal stroma. Intraocular migration, which can occur years after the initial episode, is possible and might be severe, thus requiring a life-long surveillance.

Processionary recrudescence has been observed, both in rural and urban areas. It is therefore imperative to be familiar with eye injuries caused by the insect and its treatment.