## Most Common Chemical Injury Agent **Key Point:** Alkaline (basic) substances are the most common cause of chemical eye injuries in industrial and occupational settings, accounting for approximately 50–70% of all chemical ocular injuries. ### Why Alkaline Substances Predominate 1. **Widespread Industrial Use** - Lime (calcium oxide/hydroxide) — construction, cement work - Ammonia — refrigeration, cleaning agents, fertilizers - Sodium/potassium hydroxide — detergents, drain cleaners - These are ubiquitous in factories, construction sites, and households 2. **Greater Penetration & Severity** - Alkaline agents saponify lipids in cell membranes - Penetrate deeper into corneal stroma and anterior chamber - Cause sustained damage even after initial exposure - Lead to more severe scarring and vision loss than acids ### Comparative Severity | Agent Type | Penetration | Severity | Common Examples | Prognosis | |---|---|---|---|---| | **Alkaline** | Deep, sustained | **Most severe** | Lime, ammonia, NaOH | Poor without prompt treatment | | Acidic | Superficial, self-limiting | Moderate | H₂SO₄, HCl | Better; coagulates proteins | | Organic solvents | Variable | Mild–moderate | Acetone, ethanol | Usually good | | Oxidizing agents | Superficial | Mild | H₂O₂, chlorine | Good | **High-Yield:** Alkaline injuries → worse prognosis; acids → better prognosis (due to protein coagulation that limits penetration). ### Clinical Pearl Lime (calcium hydroxide) is the **single most common** chemical in occupational eye injuries in India and developing countries due to widespread use in construction and cement work. Immediate and copious irrigation with water or saline is critical — delay in treatment worsens outcome significantly. **Mnemonic: LIME is the most common** — **L**ime, **I**ndustrial alkalines, **M**ost severe, **E**mergency irrigation needed.
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