Amblyopia
👁️ Amblyopia leads to permanent decreased vision in the affected eye if not treated early, even if the underlying ocular problem is corrected later in life. It is the most common cause of unilateral decreased vision in children and young adults.
📖 About
- Amblyopia is the failure of normal neurological development
- It represents cortical suppression of visual input from one eye during the critical period of visual development.
🧬 Aetiology
- Due to inadequate visual stimulation during the critical period of visual pathway maturation.
- Consequences include poor stereovision, reduced acuity, impaired pattern recognition, and low sensitivity to motion/contrast.
- Failure of neural network development in the visual cortex.
- MRI studies show reduced visual cortex volume in amblyopic patients.
🔎 Causes
- Three main causes: refractive error, strabismus, and media opacity.
- Most common: unilateral amblyopia from anisometropia (difference in refractive error between eyes).
- Hypermetropic anisometropia carries the highest risk.
- Myopic anisometropia is less amblyogenic, as near-vision focus offers some protection.
- Media opacity (e.g. congenital cataract, corneal dystrophy) may cause bilateral amblyopia.
🩺 Clinical
- Often asymptomatic until vision is formally tested (e.g. school screening, driving test).
- Treatment relies on penalisation of the better-seeing eye to stimulate the amblyopic eye. The commonest method is patching, but atropine penalisation drops may also be used.
- ⚠️ After ~8 years old, cortical plasticity is reduced and visual recovery is unlikely.
🛡️ Prevention
- Early detection is key — amblyopia is preventable but not reversible after the critical period.
- In the UK, all children should have a vision screen at school entry (~age 4).
- Free annual NHS eye checks are available for all children of school age.
📚 References
