Corneal perforation due to palytoxin exposure of domestic zoanthid corals.

Abstract

Editor, Palytoxin (PTX), produced by the soft coral order Zoantharia (Fig. 1, picture A), was first described by Moore and Scheuer in 1971 (Moore & Scheuer 1971). PTX is potentially lethal and inhibits the sodium potassium ATPase pump (Frelin & Van Renterghem 1995). Ocular chemical trauma due to PTX has been described in 10 patients including severe complication such as corneal melting with or without the need for surgical interventions (Moshirfar et al. 2010; Ruiz et al. 2015; Farooq et al. 2017). We report the first case in Europe of corneal perforation due to PTX as a retrospective case report of one case. The Swedish Ethical Review Authority has granted ethical approval for this research project (Dnr 2020-01603) that has been done in accordance with the guidelines of the Declaration of Helsinki. Written informed consent was obtained from the patient. A 53-year-old man was exposed to PTX gas emitted from zoanthid corals during maintenance of a domestic aquarium, immediately removed contact lenses and rinsed his eyes. From the day of exposure to the toxin (‘day one’), the patient was treated with topical chloramphenicol 5 mg/ml eye drops four times per day (QID) in both eyes. The first ophthalmological examination at the local eye clinic on day two showed bilateral conjunctivitis and staining of the corneal epithelium but no corneal melting. Topical diclofenac 1 mg/ml three times per day (TID) and carbomer 2 mg/g hourly were added. Due to development of progressive melting of the left cornea on day 10, the patient was referred to our clinic, which is a tertiary referral centre. Both eyes showed pronounced conjunctival injection, superficial punctate erosions, chemosis and follicular conjunctivitis. The right cornea had an immune system-related stromal ring infiltrate, epithelial erosion, oedema and Descemet’s membrane folds (Fig. 1, picture B). The left cornea had melted in a circular fashion and was perforated in the inferior circumference (Fig. 1, picture C). Topical treatment in both eyes was adjusted to dexamethasone 1 mg/ml eight times per day, ciclosporin 10 mg/ml BID and levofloxacin 5 mg/ml eight times per day. Intravenous, prophylactic antibiotic treatment with cefuroxime 1.5 g TID was given for three days. On day 11, penetrating keratoplasty (PKP) was performed in the left eye (Fig. 1, picture D). Cultures and direct microscopy of a smear sample were negative for bacteria and fungi. Polymerase chain reaction of scrapings from the left cornea and analysis of the resected cornea were negative for bacteria and virus infections (HSV, VZV, ESB). On day 12, systemic oral tetracycline 300 mg BID was added. After discharge from our ward on day 17, the patient continued treatment with both levofloxacin 5 mg/ml and dexamethasone 1 mg/ml TID in the right eye and five times per day in the left eye, cyclosporine 10 mg/ml BID in both eyes and atropine 10 mg/ml BID per day in the left eye only. At follow-up four months later, symptoms and signs in the right eye had resolved completely. Uncorrected distance visual acuity (UCDVA) was 1.0. The transplant in the left eye was clear and well adapted, and best-corrected visual acuity (BCVA) was 0.65. Our management of this case focused on surgical repair of the left cornea, exclusion of infection, topical anti-inflammatory and topical and systemic prophylactic antimicrobial treatment as well as systemic inhibition of matrix metalloproteinases (MMP). We advise against the use of topically applied non-steroidal anti-inflammatory (NSAID) eye drops as diclofenac due to possible melting of the cornea. This case also highlights the importance of using protective equipment when handling zoanthid corals. Thorough information to aquarists about the potential dangers involved in handling these corals is paramount.