Associations Between Choroidal Structural Parameters and Cone Photoreceptors in Young High Myopia.

PURPOSE: To evaluate the association between choroidal structural parameters and cone photoreceptor characteristics in young individuals with different degrees of myopia and to assess whether choroidal thickness (CT) may indicate early photoreceptor alterations in high myopia (HM). METHODS: Ninety-three participants aged 18 to 28 years were classified as nonmyopic, mildly to moderately myopic, or highly myopic. CT and choroidal vascularity index (CVI) were measured using swept-source optical coherence tomography angiography. Cone metrics were quantified using adaptive optics scanning laser ophthalmoscopy with automated segmentation. Cone measurements were averaged across sampling locations to derive an overall value per eye. Group comparisons and associations were analyzed using appropriate parametric or nonparametric tests, correlation analysis, and multivariable linear regression. RESULTS: CT decreased progressively with increasing myopia across all macular regions (P < 0.001), while CVI showed no significant differences. Cone density was reduced in HM, with increased spacing and reduced regularity (P < 0.001). In unadjusted analyses, cone density was positively associated with CT (r = 0.313 to 0.394, P < 0.01). Each 1-µm increase in CT corresponded to an increase of approximately 10 to 12 cells/mm² in cone density. CONCLUSIONS: Young HM eyes show concurrent reductions in CT and cone integrity, while CVI remains relatively stable. The observed associations likely reflect shared structural changes related to axial elongation rather than independent effects of CT. TRANSLATIONAL RELEVANCE: CT may serve as a practical structural biomarker for early retinal alterations in HM.