Alkali burns to the eye are more damaging than acid burns of equivalent pH. The reason is:

• A Alkalis cause immediate protein precipitation creating a barrier to further penetration
• B Alkalis have a higher osmolarity than acids
• C Alkalis cause saponification of fatty acids and liquefy tissues (liquefactive necrosis), allowing continued deep penetration into the anterior segment ✓
• D Acids penetrate more deeply than alkalis because of their lower pH

Explanation

Alkali burns cause liquefactive necrosis through saponification of cellular membrane lipids and protein denaturation, and they do NOT form a protective coagulum — allowing continued penetration into the anterior chamber, trabecular meshwork, ciliary body, and lens. Acids, in contrast, cause coagulative necrosis with protein precipitation forming a barrier that limits depth of penetration. Calcium hydroxide (lime) is among the most dangerous alkalis due to its dual coagulative and penetrating properties. This explains why alkali injuries typically cause greater final visual morbidity.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.