Multimodal imaging for paracentral acute maculopathy; the diagnostic role of en face OCT

(2021) 7:13 Riazi‑Esfahani et al. Int J Retin Vitr https://doi.org/10.1186/s40942-021-00283-y ORIGINAL ARTICLE International Journal of Retina and Vitreous Open Access Multimodal imaging for paracentral acute maculopathy; the diagnostic role of en face OCT Hamid Riazi‑Esfahani1, Elias Khalili Pour1, Kaveh Fadakar1, Nazanin Ebrahimiadib1, Fariba Ghassemi1, Ramin Nourinia2, Hassan Khojasteh1, Behnoosh Attarian2, Hooshang Faghihi1 and Hamid Ahmadieh2* Abstract Background: To describe the features of multimodal imaging and the diagnostic role of en face OCT in the paracen‑ tral acute middle maculopathy (PAMM) spectrum. Methods: In this observational case series, 5 eyes of 5 patients with acute PAMM were identified. Demographic char‑ acteristics as well as data regarding the underlying disease, presenting visual acuity (VA) and ophthalmic examination results were recorded. All patients underwent multimodal imaging within 3 days after symptom onset. Results: The mean age of patients was 52.2 (range, 33–67) years. Systemic comorbidities including diabetes mel‑ litus and hypertension were identified in two patients. Except for one patient diagnosed with isolated PAMM, other patients had signs of retinal vascular disease such as a cilioretinal artery or branch retinal artery obstruction, nonischemic central retinal vein occlusion, or a combination of these vascular disorders. The central vision was preserved in two cases; however, the remaining cases presented with profound VA reduction. Different patterns of PAMM including arterial, globular, and fern-like were observed in en face OCT at deep capillary plexus (DCP) level. En face OCT images could precisely delineate the margin of the PAMM area. Optical coherence tomography angiography (OCTA) showed decreased vascular density in DCP. Unresolved projection artifact by conventional OCTA software was observed in DCP and choriocapillaris slabs in all cases. Conclusion: En face structural OCT in PAMM can delineate the area of ischemia and the degree of foveal involve‑ ment. Unresolved projection artifact by conventional OCTA software in the PAMM area can be seen in DCP and choriocapillaris layers. Keywords: En face OCT, Multimodal imaging, Paracentral acute middle maculopathy Background Paracentral acute middle maculopathy (PAMM) is the result of an ischemic insult to the deep or intermediate capillary plexus, affecting the middle retinal layers [1, 2]. It appears in cross-sectional optical coherence tomography (OCT) B-scans as a hyper-reflective band involving the inner nuclear layer (INL) [3–5]. PAMM may occur in *Correspondence: 2 Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran, Iran Full list of author information is available at the end of the article isolation or secondary to various retinal disorders such as retinal arterial or venous occlusions and retinal vasculitis, or it may happen as a consequence of arterial hypoperfusion such as globe compression, migraine, or excessive caffeine consumption [1, 6, 7]. OCT angiography (OCTA) has provided better insight into the nature of the retinal vascular pathologies including diabetic retinopathy (DR), central retinal vein occlusion (CRVO), and arterial hypoperfusion [8–12]. OCTA delivers depth-resolved retinal vascular structure images, making it possible to differentiate capillary plexuses at superficial and deep layers of the retina; a phenomenon in which fluorescein angiography (FA) as the conventional © The Author(s) 2021. 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The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/ zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Riazi‑Esfahani et al. Int J Retin Vitr (2021) 7:13 Page 2 of 10 standard for evaluation of retinal vascular diseases fails to identify due to the superimposition of the superficial capillary plexus over the deep capillary plexus as well as being masked by leakage and hemorrhage [7, 7]. En face OCT also known as C-scan OCT is an advanced processing application of OCT images created by participating the information from whole A-scans into a picture of the retinal surface in the desired slab, allows frontal portions of retinal layers to be viewed precisely. The en face images are equal to the depth-resolved retinal fundus images with additional focus on specific sites within the region of interest [9, 10]. In this case series, we are going to describe various presentations of PAMM using multimodal imaging. We emphasize the utility of en face OCT to reveal the pattern and extension of the ischemic area. by the device module was used to visualize the level of vascular pathology. Superficial capillary plexus (SCP) was segmented from 3 µm beneath the internal limiting membrane to 15 µm beneath the outer border of the inner plexiform layer (IPL). DCP was segmented from this point down to 9 μm below the outer plexiform layer (OPL). Whenever the segmentation lines were not correctly aligned according to the parameters defined above, the automatic segmentation was corrected manually by an expert (KF), using the ‘Edit Band/Propagation’ tool on the device software. The segmentation correction began from a single most central B scan and the propagation tool was used to automatically spread the correction to other adjacent B scans [11]. En face OCT and OCTA images in superficial and deep retinal capillary plexuses of each case were extracted. Methods This study was an observational case series of 5 patients with PAMM presenting to the retina clinics at Farabi Eye Hospital and Labbafinejad Medical Center, Tehran, Iran. Informed consent was obtained from all participants. This study adhered to the tenets of the Declaration of Helsinki and was approved by the ethics committees at both centers. Patients with isolated PAMM or in association with arterial or venous occlusion were included in this study. The diagnosis was made through the ophthalmic exam and ancillary tests including SD-OCT, en face OCT, and OCTA. A thorough investigation inclu (...truncated)