Fig. 9.1
Case of MEWDS (TRC-50DX; Topcon Corporation, Tokyo, Japan); (a) Color fundus photography showing numerous subtle white spots at the RPE/deep retina level, associated with the central foveal granularity as classic presenting feature of this disease. (b) Fluorescein angiography demonstrates the early hyperfluorescence of white spots in a typical wreath-like pattern. (c) Late-phase indocyanine green angiography showing a large number of hypo-fluorescent MEWDS dots (Heidelberg Engineering, Heidelberg, Germany). (d, e) Cross-sectional B scan at time of presentation (d) showing the focal disruptions of the IS/OS junction and interdigitation zone and marked improvement of both microstructures at 4-week follow-up visit (Cirrus HD-OCT 5000; Carl Zeiss Meditec, Dublin, CA). (f, g) En face OCT images at the level of the IS/OS ellipsoid layer at time of presentation and 4-week follow-up, respectively. Green line represents location of cross-sectional B scan (d) on initial and final en face OCT. Notice that the reappearing of the IS/OS layer on the B scan is correlated with the diminishing of the dark gray spots on the en face OCT scans
Fig. 9.2
MEWDS. En face OCT scans at the level of the IS/OS ellipsoid layer at time of presentation obtained using Cirrus HD-OCT (Cirrus HD-OCT 5000; Carl Zeiss Meditec, Dublin, CA), 2-week and 4-week follow-ups, respectively, show progressive recovery of the IS/OS layer as demonstrated by the progressive disappearance of the dark gray spots
Multifocal Choroiditis and Serpiginous Choroiditis
Van Velthon et al. [15] reported the en face OCT findings of two patients affected with multifocal choroiditis (MFC) and serpiginous choroiditis (SC) , respectively. Multifocal choroiditis is a condition characterized by multifocal yellow-white spots at the level of the RPE and inner choroid, which evolve into atrophic scars [16]. Using OCT C scan, a study [15] showed that the hyper-reflective area of active lesion in MFC patients started at the vitreoretinal interface and remained visible throughout all retinal layers, reaching the RPE. This finding has important clinical relevance to illustrate that focal retinal thickening in this disease can extend into the inner retina layer.
In serpiginous choroiditis, the primary site of inflammation is assumed to be at the level of the choriocapillaris, which can secondarily involve the photoreceptor layer causing their atrophy [17]. The en face OCT findings of Van Velthon et al. [15] supported this hypothesis demonstrating that during the acute phase inflammation is limited to the deep retina and choriocapillaris structures without involvement or thickening of the inner retinal layers (Fig. 9.3).
Fig. 9.3
OCT-ophthalmoscopic images of patient with active serpiginous choroiditis lesion. (Top left) Confocal part of en face OCT C scan. Active extension (arrow) is seen as slightly less hyper-reflective area adjacent to pre-existing hyper-reflective lesion. White line indicates location at which OCT B scan was taken. (Top right) OCT part of en face OCT C scan. Active lesion is seen as hyper-reflective area at level of outer retina (arrow) just beside pre-existing parapapillary lesion. (Bottom) Cross-sectional OCT B scan shows hyper-reflective region in outer retina at side of active lesion (arrow). Figure-pending copyright release from the Van Velthon paper. VAN VELTHOVEN, M. E., ONGKOSUWITO, J. V., VERBRAAK, F. D., SCHLINGEMANN, R. O. & DE SMET, M. D. 2006a. Combined en-face optical coherence tomography and confocal ophthalmoscopy findings in active multifocal and serpiginous chorioretinitis. Am J Ophthalmol, 141, 972-5
Acute Posterior Multifocal Placoid Pigment Epitheliopathy
Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is a self-limiting idiopathic inflammatory condition involving the RPE and possibly also the choriocapillaris. Slow improvement of visual acuity is typically observed; however, if the inflammation involves the photoreceptors beneath the fovea, the visual prognosis may be limited, secondary to photoreceptor atrophy in the fovea [18].
The pathogenesis of APMPPE is still not well understood. Whereas Gass [19] originally described the placoid lesions involving the retina at the level of the RPE, Deutman et al. [20] suggested the choriocapillaris might be the site of initial insult in the acute phase, while the RPE changes could be a secondary manifestation. Increased ability to visualize this pathology using OCT has led to improved visualization of individual retinal layers involved in this disease [21, 22]. In Figs. 9.4 and 9.5, we show APMPPE findings in a patient 2 weeks after symptom onset. Using multimodal analysis, we found a correspondence between the leakage on fluorescein angiography (FA) and the hyper-reflectivity on en face OCT located at the level of the outer nuclear layer, matching the location of the lesions. Moreover, at the early stage of the disease, en face OCT scans revealed that the outer nuclear and the ellipsoid layers were more impaired compared to the RPE layer.
Fig. 9.4
Case of APMPPE. Comparing the en face OCT scans obtained using spectral-domain OCT (Cirrus HD-OCT 5000; Carl Zeiss Meditec, Dublin, CA) at the level of the outer nuclear layer (a), IS/OS ellipsoid (b), and RPE layer (c) at early stage of APMPPE shows different degrees of affection of these retinal layers
Fig. 9.5
APMPPE. FA (TRC-50DX; Topcon Corporation, Tokyo, Japan) (a) images and superimposed en face OCT scans (Cirrus HD-OCT 5000; Carl Zeiss Meditec, Dublin, CA) with decreasing transparency value, at the time of the presentation. The transparency value of the superimposed en face pictures was set at 30% in b, 40% in e, and 100% in f. The overlay shows the correspondence between the leakage from the lesions on the FA and the hyper-reflectivity on en face OCT scan (green arrowheads) located at the level of the outer nuclear layer (c). The B-scan OCT image (d) shows the disappearance of the IS/OS junction along with hyper-reflectivity of the ONL and focal thickening of the RPE
Acute Macular Neuroretinopathy
Acute macular neuroretinopathy (AMN) is a rare condition that was first described in 1975 [23]. Although the etiology is still unknown, a vascular insult to the outer retinal capillary network has been hypothesized [24]. Usually AMN affects only one eye but rarely both eyes can be involved. Patient complaints are typically the sudden onset of one or more paracentral scotomas that can persist or, more commonly, resolve partially over time. Classically the fovea is involved, but the RPE is spared [23]. Although the first reports described the lesions as affecting the superficial retinal layers, later studies demonstrated that the lesions involve the outer retina [25]. The lesions of AMN are generally better visualized with red-free photography; however, the origin of the dark lesions and the correspondence with the infrared (IR) images were not well understood. A study by our group [24] suggests that the dark lesions are related to disruption of the interdigitation zone on OCT rather than the IS/OS layer. Indeed, this hypothesis was supported by the fact that during the healing phase, when the IS/OS junction normalized, an abnormality in the interdigitation zone was still present and correlated well with the fading hyporeflective IR lesion (Fig. 9.6).
Fig. 9.6
Case 1. Lateral extension of the en face lesion corresponds to OS/RPE line during progression and healing phases. (a) Registered IR and OCT, comparing the same region of the right macula at 1 week and 6 weeks, showing lateral expansion of the IR lesion and corresponding lateral extension of OS/RPE line (arrow). Inset A focuses on the edge of the lesion and the lateral extension of the OS/RPE line. The green vertical marker on IR corresponds to the location of the vertical green line on OCT, where the original lateral margin of the lesion existed. The red arrow illustrates the location of the OS/RPE line on OCT and its corresponding overlap with the edge of the lesion on IR on both visits. Note that the IS/OS line, although attenuated, is still visible in the second visit in the region of the new lesion, whereas the OS/RPE is non discernible. (b) Infrared reflectance and OCT scans of the right eye, during resolution of the lesion. Top OCT and IR obtained at 14 weeks show that the lateral extent of the lesion has decreased compared with the IR in (a). The green vertical lines are located just inside the lateral border of the lesion, which on OCT shows relative attenuation of the IS/OS with absent OS/RPE. The red arrow again corresponds to border of intact OS/RPE, which tightly correlates to lateral border of the lesion. On follow-up, 1 year later (bottom OCT), there is improved intensity of the IS/OS and OS/RPE lines, which now both overly the edge of the lesion. Within the lesion, OCT shows slight attenuation of the IS/OS junction, with persistent absence of the OS/RPE junction. Insets highlight the respective OCT findings. Figure-pending copyright release from the Fawzi A. FAWZI, A. A., PAPPURU, R. R., SARRAF, D., LE, P. P., MCCANNEL, C. A., SOBRIN, L., GOLDSTEIN, D. A., HONOWITZ, S., WALSH, A. C., SADDA, S. R., JAMPOL, L. M. & ELIOTT, D. 2012. Acute macular neuroretinopathy: long-term insights revealed by multimodal imaging. Retina, 32, 1500-13
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