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Retinal Pigment Epithelium Activation in Angioid Streaks Imaged With En Face Optical Coherence Tomography

Ramtohul, Prithvi MD; Comet, Alban MD; Denis, Danièle MD, PhD

Editor(s): Grewal, Dilraj; Brodie, Frank L.; Feng, Henry

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doi: 10.1097/IAE.0000000000002854
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Angioid streaks (AS) refer to linear, irregular, crack-like ruptures of a calcified Bruch membrane (BM) radially spreading from the optic nerve toward the retinal periphery. Pathogenic processes include mechanical forces exerted by the extraocular muscles on a fragile and less flexible posterior pole.1 On the optical coherence tomography (OCT) B-scan, AS appear as a focal hyporeflective area of the retinal pigment epithelium (RPE)-BM complex.2 Recently, en face OCT performed at the depth of the BM has demonstrated enhancement of the visualization and characterization of AS.3

We describe a 58-year-old man diagnosed with pseudoxanthoma elasticum. Fundus photography showed peripapillary AS and macular geographic atrophy (Figure 1A). Fundus autofluorescence revealed a butterfly-shaped pattern dystrophy (Figure 1B). Angioid streaks appeared as speckled hyperautofluorescent lines (Figure 1B). En face OCT at the level of the RPE-BM complex enhanced the visualization of AS and demonstrated clustered hyperreflective dots (Figure 1C) that colocalized with the mottled RPE-BM complex on the OCT B-scan (Figure 1D). Intraretinal hyperreflective foci were also documented in the fovea on the OCT B-scan (Figure 1D). The 6-month follow-up en face OCT demonstrated loss of these hyperreflective dots and subsequent enlargement of the AS. On the OCT B-scan, marked RPE-BM complex atrophy developed within AS (Figure 2, A and B). The OCT B-scan in the superior macula depicted varying maturity of AS, including flat elevation of the RPE and RPE-BM atrophy (Figure 2C).

Fig. 1.
Fig. 1.:
A. Fundus photography showed peripapillary AS and macular geographic atrophy. B. Fundus autofluorescence revealed a butterfly-shaped pattern dystrophy, and AS appeared as speckled hyperautofluorescent lines. C. C. En face OCT at the level of the RPE-BM complex enhanced the visualization of AS and demonstrated clustered hyperreflective dots. A 20-mm thick ellipsoid zone-based contour positioned at the depth of the RPE-BM was used to obtain en face OCT images. The dashed square is a magnified view highlighting the hyperreflective dots. D. The OCT B-scan through AS highlighted the mottled RPE-BM complex (arrowheads) and intraretinal hyperreflective foci in the fovea (orange arrowheads). The green line indicates the location of the OCT B-scan.
Fig. 2.
Fig. 2.:
Baseline (A) and follow-up (B) en face OCT images showing loss of hyperreflective dots. The red arrows in the magnified views (yellow dashed squares) highlighted the horizontal enlargement of AS. A 20-mm-thick ellipsoid zone-based contour positioned at the depth of the RPE-BM complex (dashed line) was used to obtain en face OCT images. The red arrowheads delineated the RPE-BM complex atrophy. C. The OCT B-scan in the superior macula depicted varying maturity of AS, including flat elevation of the RPE and RPE-BM atrophy (arrowheads). The green line indicates the location of the OCT B-scan.

Intraretinal hyperreflective foci in AS have been described using the OCT B-scan and are supposed to be derived from the RPE cells undergoing transdifferentiation.4 In this article, we reported a novel en face OCT feature at the level of the RPE-BM complex within AS termed “hyperreflective dots.”

References

1. Chatziralli I, Saitakis G, Dimitriou E, et al. Angioid streaks: a comprehensive review from pathophysiology to treatment. Retina 2019;39:1–11.
2. Corbelli E, Carnevali A, Marchese A, et al. Optical coherence tomography angiography features OF angioid streaks. Retina 2018;38:2128–2136.
3. Hanhart J, Greifner H, Rozenman Y. Locating and characterizing angioid streaks with en face optical coherence tomography: Retin Cases Brief Rep 2017;11:203–206.
4. Romano F, Mercuri S, Arrigo A, et al. Identification of hyperreflective foci in angioid streaks. Eye 2019;33:1916–1923.
Keywords:

angioid streaks; optical coherence tomography; pseudoxanthoma elasticum; retinal pigment epithelium

Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Opthalmic Communications Society, Inc.