Intraretinal hyperreflective line in association with acute retinal pigment epithelitis

Arjan Singh; Haroon Beg; Ritika Gaur; Akshat Kothari; Manpreet Chugh; Sukanya Gorhe; Kumar Saurabh; Rupak Roy

doi:10.4103/ijo.IJO_2020_21

CASE REPORT

Year : 2022 | Volume : 2 | Issue : 3 | Page : 691-693

Intraretinal hyperreflective line in association with acute retinal pigment epithelitis

Arjan Singh, Haroon Beg, Ritika Gaur, Akshat Kothari, Manpreet Chugh, Sukanya Gorhe, Kumar Saurabh, Rupak Roy
Department of Vitreo Retina, Aditya Birla SankaraNethralaya, Kolkata, West Bengal, India

Date of Submission	04-Aug-2021
Date of Acceptance	08-Feb-2022
Date of Web Publication	16-Jul-2022

Correspondence Address:
Dr. Rupak Roy
Aditya Birla SankaraNethralaya, 147, Mukundapur, E.M. Bypass, Kolkata-700 099, West Bengal
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijo.IJO_2020_21

Abstract

Intraretinal hyperreflective line (IHL) is a novel optical coherence tomography (OCT) observation corresponding to the linear or curvilinear pattern of intraretinal hyperreflective foci. A middle aged female complained of recent onset black spot in the right eye visual field and was diagnosed as acute retinal pigment epithelitis (ARPE). On spectral domain (SD) OCT, in addition to features suggestive of ARPE, a vertical linear hyperreflective line was noted. Such IHLs have previously been reported to be present in association with various inflammatory, degenerative, or tractional conditions of macula. This is the first description of IHL in association with ARPE in published literature.

Keywords: Acute retinal pigment epithelitis, intraretinal hyperreflective line, SD OCT

How to cite this article:
Singh A, Beg H, Gaur R, Kothari A, Chugh M, Gorhe S, Saurabh K, Roy R. Intraretinal hyperreflective line in association with acute retinal pigment epithelitis. Indian J Ophthalmol Case Rep 2022;2:691-3

How to cite this URL:
Singh A, Beg H, Gaur R, Kothari A, Chugh M, Gorhe S, Saurabh K, Roy R. Intraretinal hyperreflective line in association with acute retinal pigment epithelitis. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 11];2:691-3. Available from: https://www.ijoreports.in/text.asp?2022/2/3/691/351133

Intraretinal hyperreflective foci (HRF) are described as distinct well-circumscribed lesions with similar or higher reflectivity than the retinal pigment epithelitis (RPE) band on optical coherence tomography (OCT).^[1] They are considered to be pigment-laden cells migrating into the subretinal space with associated focal photoreceptor loss and RPE atrophy.^[2]

Sometimes, the migrated pigment may show a linear or curvilinear shape appearing as a curvilinear or linear hyperreflective line on OCT B scans.

Initially described in the natural course of Acquired Vitelliform Lesions,^[2],[3],[4] similar vertical or curvilinear hyperreflective lines or foci have been reported in different RPE choroidal and vitreoretinal conditions.^[5]

We describe the presence of this peculiar pattern referred to as IHL in association with Acute retinal pigment epithelitis (ARPE).

ARPE is a self resolving self limiting benign idiopathic inflammatory disease of macular pigment epithelium first described by Krill and Deutman in 1972.^[6]

It is characterized by acute onset of visual symptoms (blurred vision, central/paracentral scotomas, and metamorphopsia) in young, healthy adults. It is unilateral, however, bilateral cases have been reported.^[6],[7] Males and females are equally affected.

Fundus examination shows pigment stippling in the macular area surrounded by hypopigmented halos.^[6],[7]

Case Report

A 39-year-old female presented with complain of seeing a black spot in the right eye (RE) visual field for 2 weeks. There was no history of any ocular disease or preceding systemic illness or fever. The patient was a known case of hypothyroidism since 12 years. The family history was unremarkable. Best corrected visual acuity in the RE was 20/40 and left eye was 20/20. Left eye examination was unremarkable. Anterior segment examination of RE was normal with a clear lens and no evidence of inflammation. There were no vitreous cells. Fundus examination of the RE revealed a round orange lesion surrounded by a hypopigmented halo in the fovea with multiple tiny hypopigmented lesions temporal to the fovea [Figure 1]a. Fundus autofluorescence (FAF) imaging of the RE showed hyperautofluorescent lesions temporal to the fovea corresponding to the hypopigmented lesions seen temporal to the fovea [Figure 1]b. Fundus fluorescein angiography of the RE revealed window defects temporal to the fovea [Figure 1]c. Spectral domain (SD) OCT of the RE revealed a subfoveal hyperreflective lesion in the outer retina with disruption of the ellipsoid zone (EZ) and interdigitation zone (IZ) with a vertical IHL extending from the hyperreflective lesion through the external limiting membrane (ELM) and terminating in the outer mid part of the outer nuclear layer (ONL). The RPE/Bruch complex below the hyperreflective lesion was mildly thickened [Figure 1]d.

Figure 1: (a): RE: Colour Fundus—Round orange lesion surrounded by a hypopigmented halo in the fovea (black arrow) with multiple tiny hypopigmented lesions temporal to the fovea (white arrow). (b): RE: FAF—Hyperautofluorescent lesions temporal to the fovea (white arrow) corresponding to the color fundus lesions. (c): RE: FFA—Window defects temporal to the fovea (white arrow). (d): RE: SD-OCT—Subfoveal hyperreflective lesion in the outer retina with vertical IHL (white arrow) extending through the ELM till ONL with EZ - IZ disruption (white arrowhead). Mildly thickened underlying RPE/Bruch complex.

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A diagnosis of acute retinal pigment epithelitis was made based on history, clinical, and imaging findings. The patient was given a course of oral steroids and followed up after 1 month. On follow-up, fundus examination of the RE revealed a reduction in round orange lesion and hypopigmented lesions [Figure 2]a. FAF imaging of the RE also showed reduction in hyperautofluorescent lesions temporal to the fovea [Figure 2]b. Spectral domain optical coherence tomography of the RE revealed that the subfoveal hyperreflective lesion and the vertical IHL had disappeared with restoration of EZ and IZ. The RPE/Bruch complex below the hyperreflective lesion was also reduced in thickness [Figure 2]c.

Figure 2: RE: Colour Fundus—Shows reduction in round orange lesion and hypopigmented lesions (a). RE: FAF—Shows reduction in hyperautofluorescent lesions temporal to the fovea (b). RE: SD-OCT—Shows resolution of subfoveal hyperreflective lesion and the vertical IHL with restoration of EZ and IZ. The RPE/Bruch complex below the hyperreflective lesion was also reduced in thickness (c).

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Discussion

In this case, we describe the presence of a vertical linear IHL in association with ARPE.

Presence of IHLs have previously been reported in association with various macular conditions like adult vitelliform dystrophy, epiretinal membrane, thick choroid, age-related maculopathy, partial resorption of subretinal or intraretinal hemorrhages, idiopathic macular microhole, vitreomacular traction, multiple evanescent white dot syndrome, fundus flavimaculatus, and pachychoroid pigment epitheliopathy.^[5],[8]

They are classified as vertical or curvilinear.^[5]

During the acute phase of retinal pigment epithelitis, we observed a linear IHL on SD OCT that resolved with the underlying condition. A similar pattern has been previously reported in multiple evanescent white dot syndrome, assumed to be an inflammatory condition involving photoreceptors and/or the RPE.^[9]

Histologically, IHLs have been shown to consist of cells of RPE origin, blood components, or inflammatory cells, all showing a similar hyperreflectivity on OCT akin to subretinal hyperreflective exudative material.

The pathogenesis of IHL is currently unclear.

Following potential mechanisms have been described in literature:^[8]

RPE layer breaks causing lipoprotein extravasation from the choroidal vessels, and its deposition in the ONL and HFL in a linear/curvilinear fashion.
Migration of RPE cells containing highly reflective melanosome, lipofuscin, and melanolipofuscin granules.
Accumulation of activated microglial cells and/or macrophages which are enlarged after phagocytosis of lipoprotein derived from the blood or degenerated photoreceptors, and which migrates from defects in the RPE to the outer neuroretina.
IHL could also represent thickened Müller cell processes containing phagocytozed lipoprotein that flowed through RPE gaps into the neuroretina during acute inflammatory damage.

However, further investigations are needed to determine the pathogenesis of IHL.

We hypothesize that, in this case, the IHL is formed due to an interplay of the later two pathogenic mechanisms described above, possibly leading to changes in the reflectivity of the central cones and Muller cells.

Conclusion

IHL appeared as a peculiar pattern, not described earlier in association with ARPE, representing a previously unnoticed response to various photoreceptor, Muller cell, and/or RPE damage.

Acknowledgements

Moupiya Das and Marina Parveen (Ophthalmic photographers).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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