A laboratory worker sustains a concentrated sodium hydroxide (NaOH) splash to the right eye. He presents 20 minutes after the injury. Examination shows marked chemosis, perilimbal ischaemia involving 8 clock hours, a hazy cornea with loss of corneal epithelium, and an IOP of 40 mmHg. Using the Roper-Hall classification, this injury is classified as:
- A Grade I — corneal epithelial erosion, no limbal ischaemia
- B Grade II — corneal haze with visible iris details, <1/3 limbal ischaemia
- C Grade III — total corneal epithelial loss, 1/3 to 1/2 limbal ischaemia, iris details obscured
- D Grade IV — opaque cornea, >1/2 limbal ischaemia, no iris details visible ✓
Explanation
Roper-Hall grade IV (Dua classification zone IV or more) indicates severe alkaline injury: opaque cornea (no iris details visible) with more than 50% (1/2) limbal ischaemia — 8 clock hours represents 2/3 limbal ischaemia, confirming grade IV. The prognosis for grade IV is guarded to poor. Alkali injuries are worse than acid because alkalis cause liquefactive necrosis, penetrating deeply and rapidly (NaOH penetrates the anterior chamber in seconds-minutes). Immediate copious irrigation for at least 30 minutes is the first priority, even before full examination, to restore conjunctival sac pH to neutral (7.0–7.4). Grade I has no limbal ischaemia; Grade II has <1/3 ischaemia; Grade III has 1/3–1/2 ischaemia.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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