What are the patterns of retinal layer thickness variation across different quadrants in low vs high myopes?

Regional Variations in Retinal Layer Thickness in Myopia

High myopes have significantly thinner retinal nerve fiber layer (RNFL) thickness in non-temporal quadrants but show a thicker RNFL in the temporal quadrant compared to low myopes. 1

Patterns of RNFL Thickness Variation Across Quadrants

Low vs High Myopia RNFL Thickness Patterns

• Global Average RNFL Thickness:

  • High myopia: Significantly thinner global average RNFL compared to low myopia (107.4 μm vs 115.8 μm) 1
  • Progressive thinning correlates with increasing myopia severity 2, 3

• Quadrant-Specific Variations:

  1. Superior Quadrant: Thinner in high myopes compared to low myopes 1, 2
  2. Nasal Quadrant: Thinner in high myopes compared to low myopes 1, 2
  3. Inferior Quadrant: Significantly thinner in high myopes compared to low myopes 1, 3
  4. Temporal Quadrant: Uniquely thicker in high myopes compared to low myopes 1

This distinctive pattern creates a different topographic profile in high myopes, with relative preservation or even thickening of the temporal quadrant despite overall RNFL thinning.

Ganglion Cell-Inner Plexiform Layer (GCIPL) Variations

Unlike the variable pattern seen in RNFL, GCIPL shows more uniform thinning in high myopia:

• Average GCIPL and GCIPL thickness in all sectors are significantly thinner in high myopic groups compared to low myopic groups 2
• GCIPL thickness correlates with spherical equivalent (1.68 μm/diopter) and axial length (-2.63 μm/mm) 2

Quantitative Relationships

• RNFL thickness correlates with:
  • Spherical equivalent: 3.67 μm/diopter 2
  • Axial length: -5.38 μm/mm 2
  • Optic disc area: 9.46 μm/mm² 2

Age-Related Considerations

The rate of RNFL thinning is accelerated in high myopes, particularly in older age groups:

• Ages 40-49: -1.70 μm/year in high myopes vs -0.48 μm/year in controls 4
• Ages 50-59: -1.69 μm/year in high myopes vs -0.63 μm/year in controls 4
• Younger age groups show less pronounced differences 4

Macular Layer Variations

Beyond RNFL, other retinal layers also show distinctive patterns in myopia:

• Central Region: Outer segment of receptors layer is thicker in high myopia 5
• Peripheral Region: Total thickness is less in high myopia due to thinning of multiple layers 5
• Specialized Layers: Combined myoid and ellipsoid zone, and combined interdigitation zone and retinal pigment epithelium/Bruch complex are thicker in the peripheral region in high myopes 5

Clinical Implications

1. Diagnostic Considerations: When interpreting OCT results, refractive status must be taken into account as RNFL thickness varies with the degree of myopia 3

2. Monitoring Progression: High myopes require more careful monitoring due to accelerated RNFL thinning rates, especially in patients over 40 years 4

3. Glaucoma Assessment: The unique pattern of preserved temporal RNFL with thinning in other quadrants must be distinguished from pathological changes

4. Longitudinal Changes: High myopic eyes show significantly greater decreases in RNFL thickness over time compared to normal eyes 4