Macular Bruch's membrane defects and other myopic lesions in high myopia

AIM: To compare the ocular fundus features of highly myopic eyes with and without macular Bruch's membrane (BM) defects and investigate the associations between macular BM defects and other myopic lesions. METHODS: This retrospective, observational case series included 262 eyes (139 patients) with high myopia (HM) refractive error >=-6.0 diopters (D) or axial length >= 26.5 mm from March 2019 to December 2019. The patients underwent a comprehensive ophthalmic examination, including swept-source optical coherence tomography (SS-OCT). The features of macular BM defects and other ocular fundus lesions were examined in OCT images. RESULTS: Totally 51 eyes (19.5%) were detected with macular BM defects, which were characterized by a lack of BM, retinal pigment epithelium (RPE), and an almost complete loss of photoreceptors or choriocapillaris. Eyes with macular BM defects had worse best-corrected visual acuity (BCVA) than those without (P<0.001). Dome-shaped macula (DSM, P=0.042), retinal cysts (P=0.006), choroidal neovascularization (CNV, P<0.001), choroidal defects and abnormality (P=0.003), scleral defects (P=0.015), scleral deformation (P=0.005), posterior staphyloma (P=0.011), and perforating vessels (P<0.001) occurred more frequently in eyes with macular BM defects. In multivariate analysis, the presence of macular BM defects remained the significant association with presence of DSM (P=0.013), sclera! defects (P=0.015), posterior staphyloma (P=0.001), perforating vessels (P<0.001) and CNV (P=0.004). CONCLUSION: Macular BM defects has a prevalence of approximately 20% in HM and it has tight association with other myopic fundus lesions. BM might be crucial in the pathogenesis of myopic fundus lesions due to its biomechanical function. A comprehensive understanding of BM's role is useful for further researches about myopic lesions.