December 2019

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Presentation Spotlight
Caterpillar spines and tarantula hairs —foreign bodies that are tricky to remove


by Stefanie Petrou Binder, MD EyeWorld Contributing Writer

An interesting case report on ophthalmia nodosa, a rare ocular inflammation caused by caterpillar spines and tarantula hairs that lodge into the ocular tissues, describes the advantage of quick action to reduce the inflammatory reaction elicited by setae within the eye and details the best way to redirect the embedded spines for easier removal. An e-poster describing the causes, incidence, clinical manifestations, and management of ophthalmia nodosa was presented by Lauren Bierman, MD, at the 2019 ASCRS ASOA Annual Meeting.
Ophthalmia nodosa is an ocular inflammatory reaction brought about by exposure to very particular types of foreign bodies, namely caterpillar spines and tarantula hairs. The very fine, pointed setae enter the eye through direct contact with the ocular surface, travelling through the ocular tissues in a straight line due to their pointed tips and microscopic barbs prevent backward motion. Toxins within the hollow spine further drive the inflammatory reaction, leading to chronic conjunctivitis, corneal scars, cataract, vitritis, and macular edema, among other things. Granulomatous nodules on the conjunctiva and iris give this entity its name.

Case Presentation 

A 27-year-old female presented to Naveen Rao, MD, with pain, tearing, and ocular redness 2 days after a large, black caterpillar was swatted into her left eye. Upon presentation, the patient had 20/20 visual acuity, IOP within normal limits, and no anterior or posterior segment inflammation.  
Slit lamp photographs of the left eye demonstrated trace conjunctival injection near the limbus with one caterpillar setae embedded in the conjunctiva and multiple caterpillar setae embedded in the corneal stroma. Anterior segment OCT of the affected eye demonstrated a setae embedded in the corneal stroma, extending down to Descemet’s membrane and threatening to penetrate through to the anterior chamber. 
Caterpillar setae can be missed due to the strong inflammatory response, which can make identification of these subtle hairs difficult, according to a study that looked at 29 eyes of 17 patients with ophthalmia nodosa, often necessitating multiple patient visits to ensure complete removal. Patients in the study described foreign body sensation, photophobia, lacrimation, redness, and eyelid edema, with hairs found in the conjunctiva, cornea, and anterior chamber.1
The patient was diagnosed with ophthalmia nodosa and a treatment strategy was devised. It included meticulous removal of all visible setae, bandage contact lens placement, and therapy with gatifloxacin q2h, prednisolone TID, cyclopentolate QHS. For the best management of the inflammation, the doctor recommended that specialists consider both ocular and systemic corticosteroids and antibiotics. Vitreoretinal surgery could be considered an option, if indicated. 
Pars plana vitrectomy was a useful management option for treatment-resistant panuveitis in an unrelated case report describing ophthalmia nodosa secondary to tarantula setae penetration in the eye of a young man. The patient suffered from chronic panuveitis despite hair removal and intensive topical steroid therapy for 18 months. The treating physician recommended early pars plana vitrectomy for cases of ophthalmia nodosa for better and faster resolution of symptoms and inflammation.2
Setae removal at a slit lamp can be difficult due to the hair size and the presence of barbs. Dr. Rao used a 30-gauge needle to rotate the hair within its tract so that the base of the cone was pointed posteriorly, and the tip of the cone pointed anteriorly. This method allowed for better traction for removal when using jeweler forceps, and took advantage of the orientation of the barbs, allowing for smoother unidirectional movement.  
Four days following setae removal, the patient’s left eye was photographed by slit lamp, demonstrating a pinpoint central stromal scar from the central setae removed from that spot. 
In another unrelated case study involving a young female patient with multiple caterpillar hairs in her cornea, sclera, anterior chamber, and pars plana, the treating physician highlighted the importance of regular follow-up visits, because the risk of delayed onset of inflammation is high in patients with ophthalmia nodosa due to the migration of setae. The case study found that early diagnosis and quick removal of setae was vital in preventing the loss of the eye secondary to extensive, recurrent inflammation caused by caterpillar hair toxicity.3
“The urticating hairs that cause ophthalmia nodosa are 0.3–1.2mm in length, and are sharp, barbed, and capable of penetrating skin, conjunctiva, and the cornea via direct transfer from the surface of fingers after contact, or even through the air,” Dr. Bierman explained. “The toxin thaumetopoein is released from the venom glands connected to the hair shaft, causing the inflammatory response. Ophthalmic manifestations can affect different eye tissues, and may include: allergic conjunctivitis, catarrhal conjunctivitis, and nodular conjunctivitis; localized or diffuse keratitis; and anterior, intermediate, and posterior uveitis; and endophthalmitis. Regular follow-up visits were highly recommended due to the risk of delayed onset of inflammation from the migration of setae,” she said.

About the doctor

Lauren Bierman, MD

New England Eye Center
Boston

Naveen Rao, MD
Lahey Hospital and Medical Center
Burlington, Massachusetts

References

1.Doshi P, et al. A Hairy affair: ophthalmia nodosa due to caterpillar hairs. Ocul Immunol Inflamm. 2018;26(1):136–141. 
2. Hom-Choudhury A, et al. A Hairy affair: tarantula setae-induced panuveitis requiring pars plana vitrectomy. Int Ophthalmol. 2012 Apr;32(2):161–3.
3. Agarwal M, et al. Indian J Ophthalmol. 2017 Mar;65(3):248–250. 

Relevant financial interests

Bierman: None
Rao: None

Contact information

Bierman: lbierman@tuftsmedicalcenter.org
Rao: Naveen.k.rao@lahey.org

Caterpillar spines and tarantula hairs —foreign bodies that are tricky to remove Caterpillar spines and tarantula hairs —foreign bodies that are tricky to remove
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