Case Report Brunei Int Med J. 2011; 7 (6): 332-335

Snake venom ophthalmia Sajid Adhi RAJA, Kenneth Yuh Yen KOK Department of Ophthalmology, PMMPMHAMB Hospital, Tutong, Brunei Darussalam

ABSTRACT

Snake venom ophthalmia is an acute reaction of the ocular surface tissues to venom ejected into the eyes of spitting victims. The condition is uncommon and the victim may be frightful of going blind. However permanent vision loss is rare. This case (40-year-old man) is reported to discuss the management protocol in such cases. Immediate copious irrigation of the eye is the most important management measure. Topical antibiotics may be prescribed to prevent secondary keratitis. Local or systemic anti-venom, topical heparin or corticosteroids are contraindicated in the management of this uncommon form of envenoming.

Keywords: Cobra venom, management, ophthalmia

INTRODUCTION The cobra snake is one of the most venomous It is well known that bites by in the world. All the cobra snakes be- can be lethal due to the neurotoxic nature of long to the and have the charac- the snake venom. Spitting cobras can eject teristic hood which helps in their easy identifi- venom precisely into the eyes of their preys cation. There are more than 20 of or predators. The effects of such envenoming, cobra; like the King cobra, which is found in termed snake venom ophthalmia have been Burma, , India, Malaysia, Philippines, reported in the literature. 1 A recent review South Africa and Thailand; the , article cites 10 cases who received venom which is found in Africa and parts of South spats in their eyes causing snake venom oph- East Asia; the , which is found in thalmia. 2 We report herein of a man who re- India and Central Asia; and the tree cobra, ceived spitting cobra venom in his eyes and which is found in Central and Western equa- discuss the management of this uncommon torial Africa. condition.

CASE REPORT Correspondence author : KYY KOK A 40-year-old man residing in a forest area in PMMPMHAMB Hospital, Tutong, Brunei Darussalam. the Tutong district tried to catch with his bare Tel: +673 8671072 or +673 2232024 E mail: [email protected] hands, a snake that had crept into his house. RAJA and KOK. Brunei Int Med J. 2011; 7 (6): 333

a b

Fig. 1: a) Slit lamp examination showing vertical superficial epithelial nebulous patches on the cornea (arrows) highlighted by box, b) magnified image of the highlighted section.

He described the snake as three feet in was mild, only oral analgesia was prescribed. length, grey to black in colour with white On follow up visit the following day, the lid spots. The snake became aggressive, reared oedema and epithelial lesions had already set- up and displayed its hood. The apprehended tled. Visual acuity improved to 6/6. Slit lamp snake then “spat” venom directly into the examination was normal. A Google image man’s eyes. He experienced very severe search results for spitting cobras was shown stinging pain and diminution of vision, associ- to him; and he identified the snake as Naja ated with excess watering in his eyes and in- siamensis . ability to keep the eyes open. He immediately washed his eyes under running tap water. A DISCUSSION couple of hours later he was seen by the oph- Spitting cobras belong to the elapid family of thalmologist at the district hospital. snakes. Naja nigricollis and Hemachatus hae- machatus are species that are commonly He was noted to have blepharospasm found in Africa. Naja siamensis or the Indo- and bilateral periorbital oedema. Visual acuity is a species of spitting cobra in both eyes was 6/9. Slit lamp examination that is found in the South-east Asian region. 3 revealed moderate conjunctival chemosis, few It is one of the six spitting cobras found in discrete vertical corneal epithelial nebulous Asia. It occupies a range of habitats including patches that stained with flourescein dye lowlands, hills, plains and woodland. It is (Figure 1). Diffuse punctuate staining in other sometimes attracted to human settlements areas of cornea without nebulae were also because of the abundant populations of ro- seen. There was no anterior chamber reac- dents in and around these areas. It is known tion. Intraocular pressure was 14 mmHg in to spit its venom up to a distance of three me- each eye. As his symptom of blepharospasm tre directly into the eyes of its attacker. Snake RAJA and KOK. Brunei Int Med J. 2011; 7 (6): 334 venom ophthalmia due to Naja atra has been trate the corneal stroma which is made up of reported from China and . 4 The collagen and is unlikely to cause permanent physiological mechanism of “venom spitting” corneal stromal opacification per se . The ocu- has been studied and is described to be a pre- lar effects of the venom depend on the prox- cise reflex mechanism aimed at ejecting imity at which ejection of venom occurs and venom forcefully into the eyes of the victims. 5 also on the duration of contact of ocular sur- The composition of spitting cobra venom has face with venom. Systemic sequelae of snake also been studied and found to contain a mix- venom ophthalmia have not been reported. 2 ture of neurotoxins, cytotoxins, phospholi- Habitually biting cobras like the Indian cobra pases and cardiotoxins. 6 Cardiotoxins have (Naja naja) can sometimes eject venom under membrane lytic properties and is thought to captivity. Provoked ejection of venom by a be responsible for corneal erosions and con- Naja naja which was held in captivity has been junctival chemosis. 7 reported to cause a transient lower motor neuron type facial palsy which resolved in a The ocular effects of envenoming by few hours. 2 On the other hand, spitting co- spitting cobras has been reported in the oph- bras can also bite. 9 thalmology literature. Fear of death or of be- coming blind can cause extreme anxiety in the Since the venom contains enzymes, afflicted person. Various remedies including longer duration of contact can be assumed to topical dilute anti-venom, 4, 6 topical heparin 6 cause more severe damage. First aid by im- and topical tetracycline 6 have been claimed mediate washing in running water is very im- to be successful in the treatment of this un- portant in removing the venom from the eyes common condition. The above reported case and help in preventing corneal complications. highlights the fact that simple copious irriga- 2 Applying bland liquids such as milk in the tion of the eyes with water alone may be all eyes may also help. Topical vasoconstrictors that is required to treat this condition. In case or patching of the eyes may aid to reduce of corneal erosions prophylactic broad spec- pain. 2 Topical broad spectrum antibiotics may trum topical antibiotics may be needed to pre- be applied to prevent secondary keratitis. A vent keratitis. 2 case of complete recovery after topical appli- cation of anti-venom has been reported. 4 A recent review article on snake However, the WHO guidelines published in venom ophthalmia by Chu et al. described the 2010 advised against the use of topical or in- clinical features seen in 10 cases. 2 Contact travenous anti-venom and topical corticoster- with snake venom results in an intensely pain- oids. 10 The use of dilute anti-venom has no ful diminution of vision associated with ble- logical basis; and it may cause local irritation, pharospasm, periorbital oedema, conjunctival adding to the patient’s discomfort. Corneal inflammation and chemosis. Initially there collagenase activity is enhanced by topical may be vertical spicular epithelial nebulae 8 steroids and in the presence of epithelial de- which take up stain, as seen in our case. The fects may cause corneal melting. Topical tet- epithelial cells lyse to form large epithelial racycline and heparin have been used to treat erosions. The venom enzymes do not pene– snake venom ophthalmia. The basic cardio– RAJA and KOK. Brunei Int Med J. 2011; 7 (6): 335

in snake venom readily binds to the review of epidemiology, clinical features, patho- acidic sites in the tetracycline molecule and physiology and management. Toxicon. 2010; heparin, and both render the cardiotoxin in- 56:259-72. 3: O’shea M, Halliday T. Smithsonian Handbook: active in experimental models. 6 and amphibians. 1st ed. New York: Dor-

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