Cornea – Basic Anatomy & Corneal Reflex
High-Yield Visual Revision
📐 Cornea Overview
- Avascular → maintains transparency
- Refractive power → +43D to +48D
- Refractive index → ~1.376
- Transparent, convex structure
🔗 Nerve Supply
- Sensory → Trigeminal nerve (CN V1)
- Via → Nasociliary nerve
- Highly sensitive tissue
⚡ Corneal Reflex Arc
Stimulus: Touch cornea
Afferent (CN V): Trigeminal nucleus
Efferent (CN VII): Orbicularis oculi
Response: Blinking
🏥 Clinical Correlation
- CN V lesion → No sensation
- CN VII lesion → No blinking
- Bell’s palsy → Lagophthalmos
⚠️ Corneal Anaesthesia Causes
- Herpes keratitis (most common)
- Diabetes • Leprosy
- Contact lens overuse
- Acanthamoeba infection
- Surgical trauma
Tap cornea: CN V senses touch → CN VII motor → Blink
