Treatment of Cobra Venom Exposure to the Eyes
Immediately irrigate the affected eye with copious amounts of water or normal saline for at least 15 minutes, followed by topical antibiotic prophylaxis and close ophthalmologic follow-up to prevent permanent vision loss.
Immediate Decontamination (Critical First Step)
- Begin irrigation immediately upon presentation with large volumes of water, normal saline, or lactated Ringer's solution for a minimum of 15 minutes 1, 2, 3
- Use at least 1 liter of irrigation fluid to thoroughly flush the venom from the ocular surface 2
- Apply topical anesthetic (such as tetracaine hydrochloride 0.5%) before irrigation if available to facilitate patient cooperation and allow adequate eyelid opening 2
- Assist patients in keeping their eyelids open during irrigation, as many will have difficulty due to pain and blepharospasm 1
- Avoid contaminating the unaffected eye during irrigation - this is a critical pitfall 1
Post-Irrigation Management
- Apply prophylactic topical antibiotic ointment (such as tetracycline hydrochloride 1% or equivalent) to the inferior fornix to prevent secondary bacterial infection 2, 3
- Consider patching the affected eye for 24 hours after initial treatment to promote corneal epithelial healing 2
- Instruct patients to continue antibiotic ointment application 2-3 times daily 2
Ophthalmologic Examination and Follow-up
- Perform careful slit lamp examination to identify corneal epithelial defects, which occur in approximately 15-20% of cases 3
- Look specifically for punctate corneal epithelial erosions, conjunctival congestion, and eyelid swelling 3
- Schedule follow-up within 24-48 hours to assess healing and monitor for complications 2
- Vitamin A ointment may accelerate corneal epithelial healing if defects are present 4
Role of Antivenom
- Systemic antivenom is generally not indicated for isolated ocular exposures, as the venom acts locally rather than systemically 5, 3
- Only 5 of 26 patients (19%) in a recent case series received intravenous antivenom, and all patients recovered without long-term sequelae regardless of antivenom administration 3
- The value of topical antivenom remains unproven and is not recommended 5
Expected Clinical Course and Prognosis
- Most patients experience significant pain reduction within 24 hours of treatment 2
- Vision typically returns to baseline within several weeks with appropriate management 2, 3
- Permanent blindness can occur in untreated or delayed cases, particularly when corneal ulceration progresses to anterior uveitis 5
- Approximately 50% of cases may develop only simple conjunctivitis without corneal involvement, while the other 50% may have corneal ulceration requiring more intensive monitoring 5
Critical Pitfalls to Avoid
- Delaying irrigation - this is the single most important intervention and must be performed immediately 1, 3
- Failing to examine for corneal abrasions with slit lamp examination 5
- Inadequate volume or duration of irrigation (must be copious and prolonged) 1, 2
- Neglecting antibiotic prophylaxis, which prevents secondary infection in damaged corneal epithelium 2, 5, 3
- Failing to arrange ophthalmologic follow-up within 24-48 hours 2