Macula and papillomacular bundle
Retina · Central scotoma
Cone-dense central retina responsible for acuity and colour vision; the fovea contains only cones with the inner layers displaced aside. Macular ganglion-cell axons form the papillomacular bundle, which enters the temporal side of the disc and runs centrally within the optic nerve.
Detail
- Photoreceptors
- Cones (colour, high acuity, photopic); rods dominate outside the macula (scotopic)
- Share of pathway
- Disproportionate: roughly half of optic-nerve axons and of the V1 map serve the central few degrees
- Cortical target
- Occipital pole
- Bedside tests
- Snellen acuity, Amsler grid, Ishihara colour plates
When it goes wrong
Macular disease (age-related macular degeneration, macular hole, macular oedema)
Central scotoma with distortion of straight lines (metamorphopsia) and reduced acuity; peripheral field and pupils normal
Papillomacular bundle damage (optic neuritis, toxic or nutritional optic neuropathy, Leber hereditary optic neuropathy)
Central or centrocaecal scotoma with early loss of colour vision and red desaturation
Practise this structure
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