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

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.

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.

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), scleral defects (P=0.015), posterior staphyloma (P=0.001), perforating vessels (P<0.001) and CNV (P=0.004).

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.