Sectoral Changes in Neuroretinal Rim Pallor Across Refractive Error.

Purpose: To investigate the association between spherical equivalent refraction (SER) and pallor in different neuroretinal rim (NRR) sectors. Design: Population-based cross-sectional study. Participants: Normal eyes of 24 057 healthy participants aged 40 to 70 years from the UK Biobank. Methods: Pallor in different NRR sectors was quantitatively derived from color fundus photographs using automated software. We first examined the association between SER and pallor in each NRR sector-controlling for age, sex, ethnicity (White vs. non-White), intraocular pressure, and mean blood pressure. We then incorporated disc-fovea distance (the shortest distance from the center of the disc to the fovea) and temporal arterial/venous concavity (extent to which the temporal artery/vein curved inwardly toward the fovea) as additional independent variables, as these features have been suggested to reflect the degree of axonal stretching at the posterior pole. Main Outcome Measures: Pallor in the temporal, temporal inferior, nasal inferior, nasal, nasal superior, and temporal superior sectors of the NRR. Results: Moving from the temporal sector to the temporal superior sector, NRR pallor varied in an asymmetrical U-shaped pattern, with the least pallor observed nasally. White participants tended to have paler NRR, but the association between SER and pallor did not differ between ethnic groups (no interaction effect between SER and ethnicity). Decreasing SER was associated with increasing pallor in all 6 NRR sectors (all Conclusions: Decreasing SER increases NRR pallor approximately 4 times faster temporally than nasally. The association between SER and NRR pallor is primarily attributable to changes in disc-fovea distance and temporal arterial/venous concavity. These findings suggest that the papillomacular nerve fiber bundle, linked to the temporal NRR, is most susceptible to myopic stretching. Financial Disclosures: The author(s) have no proprietary or commercial interest in any materials discussed in this article.