Regarding chemical injuries of the eye, all of the following statements are TRUE EXCEPT:

Question

Accepted Answer

A. Acid burns cause coagulative necrosis and typically do not penetrate beyond the corneal epithelium due to protein denaturation forming a protective barrier. ## Analysis of Chemical Eye Injuries

### Pathophysiology: Alkali vs. Acid Burns

| Feature | Alkali Burns | Acid Burns |
|---------|--------------|----------|
| **Mechanism** | Liquefactive necrosis | Coagulative necrosis |
| **Penetration** | Deep into stroma, anterior chamber, iris | Superficial; stopped by coagulated proteins |
| **Protein Effect** | Saponification of lipids; dissolves collagen | Denatures proteins → forms protective eschar |
| **Severity** | More severe; delayed complications common | Less severe; better prognosis |
| **Examples** | NaOH, KOH, ammonia, lime | HCl, H₂SO₄, acetic acid |

**Key Point:** The statement "Acid burns typically do not penetrate beyond the corneal epithelium due to protein denaturation forming a protective barrier" is **INCORRECT**. While acid burns do cause coagulative necrosis and form a protective eschar, they can still penetrate into the stroma and anterior chamber, particularly with strong acids (e.g., concentrated H₂SO₄). The depth of penetration depends on acid concentration and contact time, not merely on the formation of a barrier.

### Immediate Management

**High-Yield:** The **first and most critical step** in all chemical eye injuries (both alkali and acid) is:
1. **Immediate copious irrigation** with normal saline (or tap water if saline unavailable) for 15–20 minutes minimum
2. Evert eyelids and irrigate fornices thoroughly
3. Remove particulate matter (lime particles, etc.)
4. Check pH of tears after irrigation; continue if pH > 7.5

**Clinical Pearl:** Delay in irrigation worsens outcomes. Even 30 seconds of delay increases morbidity.

### Severity Grading (Roper Hall Classification)

Severity correlates with:
- Concentration and pH of the chemical
- Duration of contact
- Volume of agent
- Extent of corneal opacification and limbal ischemia

**Warning:** Alkali injuries have a **deceptively mild initial appearance** but lead to severe late complications (symblepharon, entropion, corneal scarring, neovascularization) due to continued tissue destruction from hydroxyl ions.

Answer

B. Alkali burns cause liquefactive necrosis and penetrate deeper into ocular tissues compared to acid burns

Answer

C. The severity of chemical injury is directly proportional to the concentration and pH of the offending agent

Answer

D. Immediate copious irrigation with normal saline for at least 15–20 minutes is the first-line management regardless of the type of chemical agent

Regarding chemical injuries of the eye, all of the following statements are TRUE EXCEPT:

Explanation

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