Ophthalmic effects of Bitis atropos (Berg Adder) envenomation

Objective: Bitis atropos, commonly known as the Berg Adder, is a venomous viperid found in Southern Africa. Envenomation is rare, with reported cases primarily exhibiting cytotoxic, neurotoxic, and myotoxic effects, including severe systemic manifestations and ophthalmologic complications such as ptosis, mydriasis, and loss of accommodation. However, the underlying pathophysiology of these sequelae remains poorly understood. Case: We present the case of a 26-year-old male who suffered severe envenomation by a Berg Adder in the Limpopo Province, South Africa. Within minutes of the bite, the patient experienced hypoesthesia, progressive dyspnea, and loss of consciousness, followed by prolonged intensive care management. Ophthalmic examination revealed bilateral dilated pupils, right ptosis, and impaired accommodation, alongside generalized muscle weakness, anosmia, ageusia, and dysphagia. Despite the absence of antivenom, the patient’s condition showed gradual improvement over a 127-day follow-up period. Notably, the pupils exhibited denervation supersensitivity, similar to Adie’s tonic pupil, and responded well to low-dose pilocarpine. Conclusion: The clinical features observed, particularly the ophthalmoplegic triad, can be attributed to the effects of phospholipase A2 proteins in the venom, which disrupt cholinergic transmission at muscarinic receptors. This case underscores the complexity of Berg Adder envenomation and highlights the variability in recovery timelines for different neuro-ophthalmic effects. This case provides valuable insights into the pathophysiology and management of severe Berg Adder envenomation, emphasizing the role of targeted therapeutic interventions such as pilocarpine in mitigating long-term sequelae.