Axial Length-Associated Structural and Microvascular Retinal Changes in Myopia: A Combined OCT and OCTA Analysis

To evaluate associations between axial length (AL) and optical coherence tomography (OCT) and OCT angiography (OCTA) parameters, including vessel density (VD) in the superficial and deep macular plexuses, radial peripapillary capillary plexus, and retinal nerve fiber layer (RNFL) thickness.

A cross-sectional observational study included 160 eyes from 160 participants, divided into four AL groups: <24.00, 24.00-24.99, 25.00-25.99, and ≥26.00 mm. The OCT/OCTA parameters were analyzed. Group differences were assessed using Kruskal-Wallis tests with Bonferroni-corrected post hoc pairwise comparisons. Associations between AL and OCT/OCTA parameters were evaluated using correlation and regression analyses.

Increasing AL was associated with superior and inferior peripapillary RNFL (pRNFL) thinning, with decreases of -2.24 µm and -3.29 µm per 1-mm AL increase, respectively (P < 0.05). The nasal pRNFL quadrant showed a positive association with AL. RPC VD demonstrated weaker associations, with limited sectoral differences. In the macula, VD decreased as AL increased, with more consistent associations in the deep capillary plexus. Each 1-mm AL increase was associated with 0.29% reduction in the superficial VD and 0.52% reduction in the deep VD.

Axial elongation in myopia is associated with region-specific pRNFL changes and reduced macular VD, particularly in the deep capillary plexus. Peripapillary vascular changes were relatively limited compared with structural pRNFL alterations. These findings suggest a distinct pattern of structural and microvascular changes compared with patterns previously reported in glaucoma, although further validation is needed in studies, including glaucoma cohorts.

Identification of AL-associated OCT/OCTA patterns may improve interpretation of retinal imaging findings in myopic eyes undergoing glaucoma evaluation.