DIROFILARIASIS OF OCULAR ADNEXA AND ORBIT

Background: Dirofilariasis is a rare helminthosis caused by nematode worms Dirofilaria repens and Dirofilaria immitis. Larvae of dirofilaria are most frequently localized subconjunctivally and are easily diagnosed. Localization of the helminth deep in eyelid or orbital tissue usually leads to false diagnosis of neoplasm. 

Aim: To describe main symptoms of dirofilariasis of ocular adnexa and orbit and to assess treatment outcomes. 

Materials and methods: 43 patients with dirofilariasis (19 men, 24 women, age 25–83 years old) were included. 

Results: Clinical symptoms of dirofilariasis were related to helminth localization and toxicoallergic reaction to its metabolic by-products. In case of subconjunctival localization, mobile (in 11 patients) or dead (in 2 patients) parasites presented as a twisted white fiber with background conjunctival injection and chemosis. In 2 patients, mobile parasites were found under the eyelid skin. In patients with dirofilaria deep in eyelid tissues (in 7 patients) or in anterior portion of the orbit (20 patients), painless mass attached to subjacent tissues was detected. Migration of the helminth was associated with exacerbated clinical symptoms: eyelid edema, eyelid skin hyperemia and increased exophthalm. After several days, eyelid and orbital edema resolved, and a new localization of helminth-induced granuloma was determined. Extraction of parasite and granuloma resulted in full recovery in all patients, no medical treatment was required. 

Conclusion: Dirofilariasis should be regarded as one more possible cause of orbital inflammation or mass. The only method of treatment of dirofilariasis is extraction of parasite and/or helminth-induced granuloma.