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

Abstract

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), scleral 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.

Changes of optic nerve head microcirculation in high myopia

“…Axial elongation is generally the result of structural changes in the posterior segment. Nonetheless, the mechanical stretching caused by axial elongation is usually accompanied by a reduction in oxygen consumption, eventually affecting the structure of the posterior segment [24][25] , such as the retina [26] .…”

Anatomic Peculiarities Associated with Axial Elongation of the Myopic Eye

“…Axial elongation beyond an axial length of approximately 26.0 or 26.5 mm is associated primarily with an enlargement of BM opening of the optic nerve head, followed by the development of secondary BM defects in the macular region [ 78 , 79 , 80 , 81 , 82 ]. These secondary BM defects correspond to patchy atrophies at stage 3 of myopic maculopathy [ 83 ]. They are associated with a complete loss of the RPE and choriocapillaris; with an almost complete absence of mid-sized and large choroidal vessels; and with a regionally more marked scleral thinning in the region of the defect, with a defect in the overlying RPE layer (usually larger than the BM defect), a defect in the overlying outer nuclear layer (usually slightly larger than the BM defect), a defect in the overlying inner nuclear layer (usually smaller than the BM defect), and so-called inner limiting membrane bridges.…”

“…Myopic macular degeneration is differentiated into stage 1 (fundus tessellation), stage 2 (diffuse chorioretinal atrophy), stage 3 (extrafoveal patchy atrophies), and stage 4 (foveally located patchy atrophies) [ 83 ]. Fundus tessellation strongly correlated with a choroidal thinning at the posterior pole, thus marked fundus tessellation is a surrogate for a leptochoroid.…”

Does PLEX® Elite 9000 OCT Identify and Characterize Most Posterior Pole Lesions in Highly Myopic Patients?

“…A tilted disk was considered to be present if the optic nerve entered the eye at an oblique angle, usually infero-nasal, while being rotated along its anterior-posterior axis [25]. We also looked for rare findings, such as macular pits defined as a sharp retina, RPE, choroid and scleral outpouching usually located within an area of patchy macular atrophy; choroidal cavitation defined as an absence of the choroidal space that is preferably located adjacent to the optic disc; scleral dehiscence defined as full-thickness scleral defects, together with outward displacement of the retina; vascular folds defined as paravascular inner retinal cleavage due to the traction of the vessels within a staphyloma detected on OCT; and perforating scleral vessels (PSV) defined as hypofluorescent vessel-like areas breaking through the sclera and reaching the choroid, demonstrating the relationship between them and other macular lesions [26][27][28]. The foveal avascular zone (FAZ) area and its perimeter at the superficial and deep retinal plexus were then manually measured using the caliper tool in the 6 × 6 OCTA macula-centered scans, where the segmentation was automatically performed by the software.…”