Corneal Anatomy and Acute Injuries
The cornea is the transparent, avascular anterior surface of the eye that provides most of the eye’s refractive power and a physical barrier to the globe. Its layered structure determines both presenting symptoms and management priorities in the emergency department: superficial epithelial injuries are often extremely painful but heal quickly, whereas deeper stromal or endothelial injury may be less painful yet pose a threat to vision.
Anatomy and clinical implications
- Epithelium
A stratified squamous layer with very high sensory innervation. Minor epithelial defects typically re‑epithelialise within 24-72 hours; exposed corneal nerves cause marked pain and photophobia. Persistent epithelial defects warrant specialist review.
- Bowman's layer (epithelial basement membrane)
An acellular collagenous sheet anchoring the epithelium to the stroma. Breaches increase the risk of scarring and irregular astigmatism.
- Stroma
Makes up approximately 90% of corneal thickness; organised collagen lamellae and controlled hydration maintain transparency. Stromal oedema, scarring or vascularisation cause lasting visual impairment.
- Descemet’s membrane and endothelium
Descemet’s is the endothelial basement membrane; the endothelium is a non‑regenerating cell layer that actively pumps fluid out of the stroma. Endothelial loss produces persistent oedema and long‑term vision loss.