A 28-year-old woman presents to the eye clinic 2 weeks after a splash of hydrochloric acid (HCl) to her left eye. She had received immediate irrigation at a nearby clinic. On examination, the cornea shows a central opacity with a 'ground glass' appearance, and the anterior chamber is quiet. Visual acuity is 6/36. The conjunctiva appears normal without blanching. What is the most likely long-term complication if she does not receive appropriate follow-up care?

Explanation

## Long-Term Sequelae of Acid Chemical Injuries **Key Point:** Acid burns cause immediate protein denaturation and coagulation necrosis, but the primary long-term complication is corneal scarring and vascularization due to chronic inflammation and wound healing. ### Comparison: Acid vs. Alkaline Chemical Burns | Feature | Acid Burns (HCl, H₂SO₄) | Alkaline Burns (NaOH, Ca(OH)₂) | |---------|------------------------|--------------------------------| | Mechanism | Coagulation necrosis, protein precipitation | Saponification, deep penetration | | Depth of penetration | Superficial (self-limiting) | Deep (progressive) | | Immediate severity | Often less severe | More severe | | Conjunctival blanching | Absent or mild | Marked, extensive | | Long-term complication | Corneal scarring, vascularization | Symblepharon, entropion, glaucoma | | Prognosis | Better (if initial injury mild–moderate) | Worse (high risk of blindness) | **High-Yield:** Acid burns are generally less destructive than alkaline burns because the coagulated protein layer acts as a barrier, preventing deeper penetration. However, chronic inflammation and neovascularization still lead to significant scarring. ### Pathophysiology of Corneal Scarring in Acid Burns 1. **Immediate phase** (0–24 hours) - Protein denaturation and coagulation necrosis - Epithelial loss and stromal edema - Anterior chamber inflammation (mild to moderate) 2. **Inflammatory phase** (1–4 weeks) - Infiltration of inflammatory cells (neutrophils, macrophages) - Angiogenesis and neovascularization of the cornea - Fibroblast activation and collagen deposition - Corneal opacity progresses from hazy to opaque 3. **Remodeling phase** (4 weeks onwards) - Continued collagen deposition and cross-linking - Corneal scarring becomes permanent - Vascularization may regress partially but leaves ghost vessels - Vision loss becomes irreversible if scarring involves the visual axis ### Management to Prevent/Minimize Scarring ```mermaid flowchart TD A[Acid chemical burn]:::outcome --> B[Immediate irrigation]:::action B --> C[Topical antibiotics + cycloplegics]:::action C --> D[Assess severity at 24-48 hours]:::decision D -->|Mild-moderate| E[Topical NSAIDs + lubricants]:::action D -->|Severe| F[Systemic corticosteroids]:::action E --> G[Prevent neovascularization]:::action F --> G G --> H[Consider anti-VEGF agents or amniotic membrane graft]:::action H --> I[Monitor for symblepharon & entropion]:::action I --> J[Planned corneal grafting if scarring severe]:::action ``` **Clinical Pearl:** The 'ground glass' appearance seen in this patient at 2 weeks indicates active corneal scarring and early neovascularization. This is the critical window for anti-inflammatory and anti-angiogenic intervention. ### Prevention of Scarring: Evidence-Based Interventions 1. **Topical NSAIDs** - Indomethacin 1% or diclofenac 0.1% - Reduces inflammation and neovascularization - Use for 4–12 weeks 2. **Systemic Corticosteroids** (in moderate-to-severe cases) - Prednisolone 1 mg/kg/day, tapered over 4–6 weeks - Reduces scar formation - Contraindicated if perforation risk or epithelial defect not healed 3. **Anti-VEGF Agents** (emerging therapy) - Bevacizumab or ranibizumab subconjunctivally - Inhibits corneal neovascularization - Improves long-term visual outcomes 4. **Amniotic Membrane Graft** - Reduces inflammation and promotes epithelialization - Indicated in severe cases or persistent epithelial defects 5. **Lubricants & Protective Measures** - Frequent artificial tears - Protective eyewear to prevent re-injury - Treat dry eye aggressively **Warning:** Posterior synechiae (option A) and secondary glaucoma are more common in alkaline burns due to deep anterior chamber involvement. In acid burns, the primary issue is corneal scarring, not posterior segment inflammation. ### Prognosis in This Case With a visual acuity of 6/36 at 2 weeks and corneal opacity, this patient is at high risk for permanent vision loss due to scarring. Aggressive anti-inflammatory therapy now is crucial to prevent further deterioration.