DISCUSSION

Ticks are a ubiquitous species that have been identified across various continents, including North America, Europe, Africa, and Asia.^{Reference Hu1, Reference Kilpatrick, Dobson and Levi2} Although local sequelae of tick bites usually resolve upon removal of the arachnid, appropriate forethought should be given to the management of these patients to manage any associated complications. A thorough history and detailed physical examination are useful to guide ongoing management.

Of the myriad of complications associated with a tick bite, the most devastating and immediate systemic complications include those of anaphylaxis, which have been reported.^{Reference McGain, Welton, Solley and Winkel3} More specific concerns include envenomation with neurotoxins, which can cause ascending paralysis, respiratory failure, and death.^{Reference Hall-Mendelin, Craig and Hall4,Reference Morshed, Li and Lee5} These manifestations are life-threatening and should be promptly identified and managed in the emergency setting.

Of immediate interest in this presentation would be the exclusion of injuries to the globe and its adnexa. This may arise directly at the site of trauma and can be associated with bleeding and ulceration, as in our patient.

A breach of the skin barrier permits the introduction of pathogens, which can result in cellulitis.^{Reference Arslan, Karagoz, Zemheri, Vahaboglu and Mert6} The removal of the tick should be done gently and carefully to ensure that no remnants are retained, as this may act as a nidus for subsequent infections in the form of preseptal or orbital cellulitis. The application of liquid butane has been reported to asphyxiate ticks and assist in the relaxation of its hypostome.^{Reference Santos-Bueso, Calvo-Gonzalez, Diaz-Valle, Benitez-del-Castillo and Garcia-Sanchez7} In our patient, the application of topical chlorhexidine 0.05% may have served a similar purpose.

After removal of the tick, patients should be monitored closely for the development of secondary ocular complications, such as preseptal cellulitis and orbital cellulitis. Patients with preseptal cellulitis typically present with periorbital swelling and associated erythema, tenderness, and warmth. This may be associated with mild conjunctival injection and chemosis. Of concern for orbital cellulitis would be the presence of severe chemosis and conjunctival injection, proptosis, pain, and limitation of ocular motility. This may be accompanied by signs of optic nerve dysfunction, including a reduction in visual acuity, dyschromatopsia, and the presence of a relative afferent pupillary defect. Patients may also be constitutionally unwell and febrile. This diagnosis may be further supported by dedicated orbital imaging and represents a life and sight-threatening ophthalmic emergency. The prompt commencement of systemic broad-spectrum antibiotics should be achieved. Patients also require an admission to the hospital for further monitoring and management.

The ocular surface should also be carefully inspected for the presence of retained foreign bodies, which can inflict further trauma to delicate structures, such as the cornea and can even result in secondary infections. Although direct injuries to the skin surface typically resolve, resulting scarring may lead to eyelid malpositioning, such as ectropion. Consequently, eyelids may be unable to protect the ocular surface while malpositioned eyelashes can further damage the ocular surface.

Nonspecific local complications, including contact dermatitis, granuloma formation, allergic reactions, and secondary infections, are further associated with tick bites.^{Reference Lin, Yeung, Sun, Ku and Yang8} These conditions may manifest in a delayed fashion, and patients should be further advised to return for an evaluation if signs and symptoms suggestive of these complications arise.

An important consideration in this instance would include vector-borne diseases. Because these are usually region- and species-specific, tick-borne diseases should be considered based on locality and antecedent travel history. Conditions such as Lyme disease are important considerations in temperate regions, whereas other conditions such as severe fever with thrombocytopenia syndrome may be more relevant in Asia.^{Reference Kilpatrick, Dobson and Levi2,Reference Luo, Zhao and Wen9} However, given climate change and the relative ease of travel, diseases may not be contained within regions, and careful consideration needs to be provided surrounding associated conditions.^{Reference Ogden and Gachon10} Patients should be warned about the development of commonly associated systemic symptoms such as a rash, fatigue, muscle aches, and fevers. Further ophthalmic manifestations of Lyme disease may include the presence of a follicular conjunctivitis, nummular keratitis, and uveitis.^{Reference Ehntholt and Zaidman11,Reference Howlett and Booth12} Cranial nerve involvement has also been reported.^{Reference Halperin13,Reference Träisk and Lindquist14} Discussions with the infectious diseases team regarding antimicrobial prophylaxis and further follow-up may be appropriate.