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The Official Scientific Journal of Delhi Ophthalmological Society
Bilateral Corneal Melting Following Snakebite
Manisha Meena, Neha Singh, Poonam Kishore 
Department of Ophthalmology, King George Medical University, Lucknow, Uttar Pradesh, India
Corresponding Author:
Manisha Meena 
Former Junior Resident
Department of Ophthalmology
King George Medical University
Lucknow, Uttar Pradesh, India
Email id: manishameena1905@gmail.com
Published Online: 30-JUL-2018
DOI: http://dx.doi.org/10.7869/djo.384
A 45 year old man presented with bilateral corneal melting following snake bite. Bilateral corneal melting is a very rare complication after snakebite. The clinical picture is described. Patients with bilateral corneal melts are more likely to have a favourable outcome if treated early.
Keywords : snakebite, hemotoxin, neurotoxin, corneal melting
Snakebite is an environmental hazard associated with significant morbidity and mortality in the rural population of developing countries. Despite the scale of its effect on populations, snakebite has not received the attention it deserves from national and international health authorities, and has been appropriately categorized as a ‘neglected tropical disease.1 In India, an estimated 200,000 persons per year fall prey to snakebite, with an estimated fatality rate of 35,000-50,000 per year.2 South Asia is the world’s most heavily affected region, due to high population density, widespread agricultural activities, numerous snake species and lack of functional snake bite control programs.3
Isolated case reports describing ocular manifestations of snake bite have been reported in the literature. These include ophthalmoplegia, uveitis, glaucoma, central retinal artery occlusion, macular infraction, optic neuritis, vitreous hemorrhage, penetrating eye injury, globe necrosis, cortical infarction and endogenous endophthalmitis. However, no reports of corneal complications such as corneal melting were found in the literature. The aim of this case report is to highlight the corneal complications after snakebite.

Case History 
A 45 year old male, farmer by occupation, had a history of snake bite 25 days back in the second finger of the left hand. After the bite, he tied his upper arm with vinyl cloth and was brought by his wife and daughter to the trauma centre of our hospital. The patient also had a history of unconsciousness for 10 days after 24 hours of snakebite.
He was admitted in the intensive care unit of our hospital was referred to the ophthalmology unit. He presented to us with complaints of inability to open both eyes, redness, watering, photophobia and whitish discoloration of clear central part of both eyes since 15 days. 

On examination, the patient had blepharospasm and limb weakness. He was unable to walk, walk with the support of another person. His visual acuity in both eyes was finger counting close to face with accurate projection of rays in all quadrants. Anterior segment findings of both eyes showed mildly oedematous lids, marked conjunctival congestion, severe corneal thinning of the cornea with sloughing in the lower part 3mm × 3mm in size, a flat anterior chamber in lower part and shallow AC in upper part, and a cataractous lens. Corneal sensation was decreased in both eyes. Fundus examination was not possible. Ultrasound B scan done for posterior segment assessment showed no abnormality. We advised topical antibiotics and cycloplegics after bandage contact lens (BCL) application in both eyes and the patient was kept on close observation. Tectonic kaeratoplasty had to be done in the left eye at 2 weeks due to further worsening of the clinical condition. The medical records revealed finger swelling and black pigmentation near the bite mark. The patient had received the appropriate antivenom. His blood counts one day following the snakebite were: hemoglobin 14.2gram%, total white blood cells count 14,500/microliter, platelet count 2.6 lacs/ microliter, blood urea 18 milligram/ deciliter and serum creatinine 0.56 milligram/ deciliter. He was diagnosed as suspected snake bite with neurotoxicity with corneal melting. Systemic condition of the patient had improved after the medical treatment.

In general, venoms are described as neurotoxic or hematotoxic. Cobra and krait envenomation is typically neurotoxic whereas envenomation by Viperidae species shows characteristic vasculotoxic and haematotoxic features. Patil et al3 reported that 85.43% cases in their series were vasculotoxic and 14.56% were neurotoxic. In our case, the snake was suspected as neurotoxic. Seneviratne et al4 in their study of 56 patients with neurological manifestations of snake bite, reported that ptosis and ophthalmoplegia were the commonest neurological manifestations. Singh et al,5 in an analysis of 33 venomous snake bites in a military operational area of north India reported 21 patients to be neurotoxic in nature.
Ophthalmic manifestations of snakebite have rarely been reported in the literature. However, the common problem described after snakebites is a neurological disturbance in the form of ophthalmoplegia. Other ocular disturbances observed as effects of snakebites range from keratomalacia to vitreous hemorrhage, including uveitis, glaucoma, central retinal artery occlusion, macular infarction, optic neuritis, penetrating eye injury, globe necrosis and visual loss due to cortical infarction. 
In our case, there was primary involvement of the cornea. We postulate that neurotoxic snake venom caused neurotrophic keratitis. Sensory nerves exert a trophic influence on the corneal epithelium. The sensory neuromediators acetylcholine, substance P, and calcitonin gene-related peptide have been shown to increase epithelial cell proliferation in vitro. Denervation, on the other hand, results in decreased cell metabolism, increased permeability, decreased levels of acetylcholine, and decreased cell mitosis. Because a continuous turnover of corneal epithelial cells occurs, this can lead to an epithelial defect even in the absence of injury. Sympathetic neuromediators and prostaglandins decrease epithelial cell mitosis. In fact, ipsilateral sympathetic denervation appears to mitigate the effects of corneal sensory denervation.
Venom is a complex mixture of proteins which affects both hemostatic and neurologic systems. Antihemostatic factors of viper venoms can lead to acute fibrinolysis, severe reduction of platelet levels and damage to the vascular endothelium. Viper venoms may also cause breakdown of permeability barriers provoking fluid extravasation and edema. Peripheral neutrophil count can increase up to 20,000 cells/µL or more in severely envenomed patients. Initial hemoconcentration, a consequence of plasma extravasation, is followed by anemia caused by bleeding or, more rarely, hemolysis. Thrombocytopenia is a common effect of pit viper bites. Hyaluronidase and collagenase, proteolytic enzymes that are also compounds of viper venoms, may induce disruption of retinal veins that, in turn, result in retinal hemorrhage.

Bilteral corneal melting is indicative of neurotoxic bite and early treatment in association with the neurologist may save the vision and life of the patient. In our case, neurotrophic keratopathy was the cause of bilateral corneal melting. Tectonic keratoplasty is a better option to salvage the vision.

  1. Warrell DA, Gutiérrez JM, Calvete JJ, Williams D. New approaches & technologies of venomics to meet the challenge of human envenoming by snakebites in India. Indian J Med Res 2013; 138: 38-59. 
  2. Brunda G, Sashidhar RB. Epidemiological profile of snake bite cases from Andhra Pradesh using immunoanalytical approach. Indian J Med Res 2007; 125:661-8.
  3. Patil VC, Patil HV, Patil A, Agrawal V. Clinical Profile and outcome of envenomous snake-bite at tertiary care centre in western Maharastra. Int. J Med. Public Health 2011; 4:28-38.
  4. Seneviratne U, Dissanayake S. Neurological manifestations of snake bite in Sri Lanka. J Postgrad Med 2002; 48:275-8 
  5. Singh J, Bhoi S, Gupta V, Goel A. Clinical profile of venomous snake bites in north Indian Military Hospital. J Emerg Trauma Shock 2008; 1:78-80. 
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Manisha Meena, Neha Singh, Poonam KishoreBilateral Corneal Melting Following Snakebite.DJO 2018;29:70-71
Manisha Meena, Neha Singh, Poonam KishoreBilateral Corneal Melting Following Snakebite.DJO [serial online] 2018[cited 2019 Mar 24];29:70-71. Available from: http://www.djo.org.in/articles/29/1/Bilateral-Corneal-Melting-Following-Snakebite.html
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