1

Introduction

Palytoxin is a complex compound found in marine organisms and soft corals that functions as a chemical defense by inhibiting the sodium‑potassium ATPase [ , ]. Human toxicity occurs through ingestion, direct contact, or inhalation of PTX [ ]. Corneal tissue is uniquely susceptible as it displays a high concentration of ATPases [ ]. Disruption of this membrane gradient can lead to keratoconjunctivitis, iritis, or corneal perforation [ ]. Emergency medicine physicians may be unaware of the dangers associated with PTX.

This case report describes a patient who experienced suspected PTX-induced ocular toxicity following exposure to a zoanthid coral species in a home saltwater aquarium. Despite a delay to presentation and an elevated ocular pH, he had a favorable clinical outcome.

2

Case

We treated a 27-year-old man who presented to the emergency department (ED) with unilateral eye pain, redness, and decreased visual acuity. Twenty hours prior to presentation, the patient cleaned his saltwater fish tank and attempted to remove invasive palythoa coral ( Fig. 1 ), inadvertently splashing a substance into his right eye. The patient rinsed his eye with water and removed his contact lenses.

Coral species from the patient’s home saltwater fish tank. White arrow points to palythoa coral.

On ophthalmologic exam in the ED, the affected right eye had 2+ conjunctival injection ( Fig. 2 ), visual acuity of 20/50, intraocular pressure (IOP) of 21 with preserved visual fields. There was no epithelial defect with fluorescein dye. Initial pH of the ocular surface was 9, measured via paper test strips. The unaffected left eye had no conjunctival injection and visual acuity was 20/30 with an IOP of 18. The patient’s vital signs were normal.

Edematous conjunctiva with diffuse injection, after dilation.

We treated the patient by performing ocular irrigation with 5 L of 0.9% sodium chloride solution using a Morgan Lens irrigation device. Ocular pH subsequently improved to 7–8 and visual acuity to 20/25. The patient was discharged home with erythromycin 0.5% ointment twice daily and both prednisolone acetate 1% and artificial tears every 4 h. He was referred to follow up in the ophthalmology clinic in 1–2 days, however was lost to follow-up.

We contacted the patient by phone one month after ED evaluation. He reported using the prednisolone and erythromycin for one week. He experienced a dull headache, sinus congestion, and generalized fatigue for 3 days after evaluation, followed by complete symptom resolution and return to baseline subjective visual acuity within 3 days.

3

Discussion

This case details the presentation, clinical course, and treatment of ocular palytoxin exposure. At present, no clinical assay exists to detect PTX so emergency clinicians must maintain a high index of suspicion. Similar to other case reports, our patient presented with ocular irritation, local inflammation, and reduced visual acuity. He was also found to have an elevated ocular surface pH. To the best of our knowledge, there have been no other documented cases of pH exceeding 8.5 as in our patient [ ]. Although alkaline chemical exposures are typically associated with a higher morbidity as compared to acidic exposures, the degree of pH elevation in this case did not correlate with the severity of corneal damage [ , ].

Given the relative scarcity of literature on ocular PTX exposure, no consistent treatment guidelines currently exist. As with most chemical exposures, early irrigation to remove residual toxin and normalize pH is important. Topical steroids may prevent progression to corneal perforation, although prolonged use impairs wound healing and can paradoxically contribute to ulceration [ , , , ]. Alternately, systemic steroids have been useful in cases with significant inflammation or symptom progression despite topical agents [ , ]. Topical antibiotics may prevent secondary bacterial infections. Interestingly, several case reports also used oral doxycycline for its proposed inhibitory effects on collagenolysis [ , , , ]. Finally, adjunct therapies such as ascorbic acid, amniotic membrane transplant, therapeutic contact lenses, and autologous serum eye drops have also been described in the literature [ , , ].

Systemic PTX toxicity can range from lethargy or GI distress to rhabdomyolysis and ultimately cardiac or respiratory failure, depending on the route of exposure [ , ]. Inhalation in particular is associated with significant morbidity so a careful evaluation for hypoxia, dyspnea, and chest pain is crucial as exposure through multiple routes simultaneously is possible [ ]. Based on existing literature, it is unclear if the effects of ocular exposure self-limited, or if they can lead to more widespread toxicity. Fortunately, there are no reports of fatality in cases of isolated ocular exposure [ ]. On presentation our patient did not display evidence of systemic exposure but did report headache, fatigue, and sinus congestion post-discharge which could represent delayed toxic effects.

4

Conclusion

We report a case of ocular irritation, visual disturbances, and the highest reported ocular pH following PTX exposure. At a minimum, treatment should include ocular irrigation, topical steroids, and topical antibiotics. Given the potential for PTX-containing compounds in household saltwater aquariums, emergency physician awareness and patient education regarding safe coral handling are important to optimize outcomes.

CRediT authorship contribution statement

Annabelle Croskey: Writing – review & editing, Writing – original draft, Project administration, Data curation, Conceptualization. William Trautman: Writing – review & editing, Supervision, Project administration, Data curation, Conceptualization. David Barton: Writing – review & editing, Supervision, Project administration, Data curation, Conceptualization. Mary Kathleen Ratay: Supervision, Data curation, Conceptualization. Joshua Shulman: Writing – review & editing, Supervision, Project administration, Data curation, Conceptualization.