Misalignment Between Center of Foveal Avascular Zone and Center of Foveal Photoreceptors in Eyes With Idiopathic Epiretinal Membrane

Abstract

To determine the degree of misalignment between the center of foveal avascular zone and the center of foveal photoreceptors in eyes with an idiopathic epiretinal membrane (ERM).Methods: We reviewed the medical records of 61 eyes with an idiopathic ERM. A 3 • 3 mm area centered on the fovea was scanned with optical coherence tomography angiography before and at 6 months after surgery. The center of foveal avascular zone and the center of foveal photoreceptors were detected by en-face optical coherence tomography angiography images and sequential optical coherence tomography B-sections in the macular region. The presence or absence of ectopic inner foveal layers was also evaluated.Results: The mean distance from the center of foveal photoreceptors to the center of foveal avascular zone was 111.7 ± 106.8 mm in eyes with preoperative ERM. This distance was significantly correlated with the preoperative central foveal thickness (r = 0.33, P = 0.0104). Preoperatively, the ectopic inner foveal layers were present in 27 (44.3%) of 61 eyes. The foveal misalignment was greater in eyes with ectopic inner foveal layers than in those without ectopic inner foveal layers (158.6 ± 140.0 vs. 74.4 ± 45.4 mm, P , 0.0003). At 6 months after ERM surgery, the foveal misalignment was significantly reduced to 73.7 ± 48.0 mm (P = 0.0018).Conclusion: Determining the degree of misalignment between the center of foveal avascular zone and the center of foveal photoreceptors might be a useful way to evaluate the degree of ERM traction.

Distance between the center of the foveal avascular zone measured automatically and the highest foveal bulge using OCT angiography

“…Hasegawa et al reported the degree of misalignment between the center of the FAZ and the highest FB point in individuals with ERM in one eye and a healthy contralateral eye. 16 The mean distance from the highest FB point to the center of the FAZ was 38.7 ± 20.0 µm in the healthy eyes, which is consistent with the results of the current study. The previous study reported that the degree of misalignment between the center of the FAZ and the highest FB point was greater in eyes with more advanced ERM, which may be useful for evaluating the degree of ERM traction.…”

“…18 The program utilizing the OCTA instruments faced several limitations, and required manual delineation of FAZ, unlike in this study. 16 The automated methods are more objective and reproducible than the manual method, and the speci c KSM method and its clinical applications have been reported. 15,18 The identi cation of the FAZ has excellent reproducibility and is comparable to measurements obtained manually.…”

“…Several recent studies have reported that the FB, foveal pit (FP), and center of the FAZ, which are considered to indicate the center of the central fovea, are misaligned even in healthy eyes. 16,17,19 Kuppuswamy et al reported that the position of the FB nasally deviates from the FP in healthy eyes, with a median distance of 58.6 μm. 19 Matsui et al reported that the highest FB point was on the nasal side of the FP in 97 eyes (66%) and the superior side of the FP in 82 eyes (55%) in a study of young, healthy, Japanese participants.…”

“…12 In addition, the FAZ has been evaluated in glaucoma, 13,14 15 and idiopathic epiretinal membrane (ERM). 16 In recent reports, the center of fovea pit, center of the FB, and center of the FAZ have been located manually using OCT angiography (OCTA), though the manually-located landmarks are not always accurate. 16,17 Recently, we generated and reported a macro program to automatically determine the FAZ area using OCTA.…”

“…16 In recent reports, the center of fovea pit, center of the FB, and center of the FAZ have been located manually using OCT angiography (OCTA), though the manually-located landmarks are not always accurate. 16,17 Recently, we generated and reported a macro program to automatically determine the FAZ area using OCTA. 15,18 Although previous studies have suggested that both the FAZ and FB are critical biomarkers of the functional properties of the fovea in eyes with various retinal diseases, the spatial relationship between the center of the FAZ in en-face images and the highest FB point are poorly understood.…”