The Ocular Complications of an Envenomous Snakebite

An envenomous snakebite is an important public health problem that can lead to irreversible loss of vision. Snake venom neurotoxins mainly act on the peripheral nervous system at the neuromuscular junction; and result in the implication of the cranial nerves. Consequently; mild neurological symptoms that relate to cephalic muscle paralysis; including exotropia; ptosis; diplopia and ophthalmoplegia; can occur. This happens because the extraocular muscles are especially susceptible to neurological muscular blockage. Other neurological complications of snake venom include accommodation paralysis; optic neuritis; globe necrosis; keratomalacia; uveitis; and loss of vision due to cortical infarction. Haemostatic complications may include subconjuctival haemorrhage; hyphema; and vitreous and retinal haemorrhages. Another rare complication of a snakebite is ocular injury. Snakebite injuries are often accompanied by facial swelling; periorbital ecchymosis; massive subconjuctival haemorrhage; severe corneal oedema and exophthalmos in the affected eye. Unfortunately; such injuries result in permanent loss of vision; as early evisceration is deemed necessary to reduce the amount and effect of the venom in the affected eye. With such a variety of ocular complications as a result of a venomous snakebite; it is important for primary care physicians to have some basic knowledge of the management of these complications; as they may prove to be vital where patients present with a snakebite and possible venom injection in the eye

Management of Snakebites at a Rural South African Hospital

Background: Snakebites remain a source of considerable morbidity and mortality in many countries with an estimated global true incidence of envenomation exceeding five million per year; with about 100 000 of these cases developing severe sequelae. Despite the availability of polyvalent snake antivenom; inappropriate first aid; the regional effects of envenomation; and inappropriate use of antivenom result in significant and at times potentially avoidable; morbidity and mortality - particularly in children. The study was undertaken in Ellisras (now Lephalale) hospital; Limpopo province due to the frequency of snake bites managed at the hospital. Methods: This was a record-based retrospective study in which patient files with the diagnosis of snake bite were reviewed. The objective of this study was to document the management of snakebites at Ellisras (now Lephalale) hospital; Limpopo; a rural hospital in South Africa. The hospital files of all patients managed at the hospital for snakebites from 1 January 1998 to 31 December 2001 were reviewed. Results: Seventy patients were treated for snakebites during the study period. The results showed a male preponderance (60) and a mean age of 27.3 years among the reported cases managed for snakebites. Twenty-nine patients (41.1) were bitten between dusk and dawn (18h00 and 06h00); 43 (61.4) were bitten on the lower limb and the mean duration of admission in the wards was 4.2 days. Twenty-one bites (30) were attributed to known poisonous snakes; 22 (31.4) received polyvalent antivenom; 42 (60) received promethazine which has not been shown to prevent anaphylactic reactions; 12 (17.1) developed complications; and 2 died (case fatality rate of 2.9). Conclusion: The findings of this study highlight gaps in the management of snake bites at this rural hospital where they occur frequently. It is crucial for primary care physicians to be familiar with the most common venomous snakes in South Africa and the management of their bites in humans. The importance of administering prophylactic antibiotic; tetanus toxoid in all confirmed snakebites; and close monitoring of all patients during and after antivenom administration form the basis of most clinical protocols on the management of snakebites