Polarized Light Microscopy-Based Quantification of Scleral Collagen Fiber Bundle Remodeling in the Lens-Induced Myopia Mouse Model

Scleral remodeling plays a crucial role in myopia development. Although ultrastructural collagen changes have been described, quantitative assessment at the fiber bundle level remains limited. This study quantitatively evaluated scleral collagen remodeling in a lens-induced myopia (LIM) mouse model using polarized light microscopy (PLM) combined with picrosirius red (PSR) staining. LIM was induced in C57BL/6J male mice by applying a monocular −30 D lens from postnatal week 3 to 6. Eyes wearing −30 D lenses showed myopic shifts in refraction (−8.42 ± 3.87 D vs. 4.42 ± 4.45 D; p = 0.002) and axial elongation (0.21 ± 0.04 mm vs. 0.18 ± 0.05 mm; p = 0.020) compared with contralateral controls. PLM revealed looser, more disorganized collagen bundles in myopic sclera. Quantitative analysis showed reduced bundle proportion (40.91 ± 6.58% vs. 48.36 ± 6.47%; p = 0.040) and mean size (147.11 ± 59.38 µm2 vs. 281.45 ± 101.00 µm2; p = 0.002). These results indicate that myopia development involves structural remodeling of the sclera and that PLM with PSR staining provides a practical approach for quantitative wide-field evaluation of collagen architecture in experimental myopia.