Strong association between decreased stroma in Sattler's layer and high myopia

To investigate the choroidal vascular area (VA) and stromal area (SA) in the small vascular layer (SVL), Sattler's layer (SL), and Haller's layer (HL) in myopia.

A total of 280 myopic eyes from 150 subjects were enrolled, including low myopia (LM), moderate myopia (MM), and high myopia (HM). Two scans (one horizontal and one vertical) passing through the fovea were obtained from the cube data of spectral-domain optical coherence tomography (SD-OCT), the choroidal area (CA), VA, SA, and choroidal vascularity index (CVI) of the SVL, SL, and HL were acquired using the Niblack's method. The choroidal parameters were compared among groups.

Compared to LM, CA decreased significantly in all subregions of MM and HM (P < 0.05), with HM showing a greater decline. SVLCA decreased in fovea and superior regions in MM and HM, but only decreased in the superior region when comparing HM with MM. Relative to LM and MM groups, SLCA demonstrated significant reductions across all subregions in HM (P < 0.05). Similarly, HLCA, HLVA, and HLSA exhibited decreased levels in foveal and nasal regions. Notably, the HM group presented elevated HLCVI in temporal and superior regions, along with higher foveal SLCVI compared to other groups (P < 0.05). After adjusting for age as confounding factor, generalized estimating equation analysis demonstrated a significant association between SLSA and HM (P < 0.05). Notably, the reduction in SLSA within the nasal region exerted the most pronounced influence on the HM (accuracy = 0.64).

Different choroidal vascular layers exhibit distinct responses to varying degrees of myopia, and the reduction in SA may precede that in VA. Reduced SVLCA, SLCA and HLCA in MM may signal early myopia progression; fundus changes in MM also warrant focus. Trial registration number and date of registration for prospectively registered trials: 2022-SR-544, December 6, 2022. Key messages What is Known: • Choroid may be involved in refractive adjustment and axial growth and is related to the alterations in Haller's and Sattler's layers.

• Different choroidal vascular layers exhibit distinct responses to varying degrees of myopia, and the reduction in stromal area may precede that in vascular area. • Reduced choroidal small vascular layer area, Sattler's layer area and Haller's layer area in moderate myopia may signal early myopia progression; fundus changes warrant focus. • The reduction in stromal area of Sattler's layer was highly associated with high myopia, especially prominent on the nasal region.