Sectoral Changes in Neuroretinal Rim Pallor Across Refractive Error.

Area of Science:

• Ophthalmology
• Neuroscience
• Biomedical Engineering

Background:

• Spherical equivalent refraction (SER) is a key refractive error.
• Neuroretinal rim (NRR) pallor is an indicator of optic nerve damage.
• Understanding the relationship between SER and NRR pallor is crucial for diagnosing and managing eye conditions.

Purpose of the Study:

• To investigate the association between spherical equivalent refraction (SER) and pallor in different neuroretinal rim (NRR) sectors.
• To determine if anatomical factors like disc-fovea distance and arterial/venous concavity mediate this association.

Main Methods:

• A population-based cross-sectional study of 24,057 healthy participants aged 40-70 from the UK Biobank.
• Quantitative derivation of NRR pallor from color fundus photographs using automated software.
• Statistical analysis to examine the association between SER and NRR pallor, controlling for covariates and incorporating disc-fovea distance and temporal arterial/venous concavity.

Main Results:

• NRR pallor exhibited an asymmetrical U-shaped pattern, with least pallor observed nasally.
• Decreasing SER was associated with increasing NRR pallor in all sectors (P < 0.001).
• The temporal and temporal inferior sectors showed the steepest increase in pallor with decreasing SER, approximately 4 times faster than nasal sectors. Disc-fovea distance and temporal arterial/venous concavity accounted for ≥50% of the effect of SER on NRR pallor.

Conclusions:

• Decreasing SER significantly increases NRR pallor, with a marked temporal-to-nasal gradient.
• Disc-fovea distance and temporal arterial/venous concavity are key mediators of the relationship between SER and NRR pallor.
• These findings suggest the papillomacular nerve fiber bundle, associated with the temporal NRR, is most vulnerable to myopic stretching.