Pigmented paravenous retinochoroidal atrophy associated with unilateral cystoid macular oedema

Abstract

A 65-year-old man was referred to our department with complaints of blurred vision in the left eye. Funduscopic examination revealed areas of retinochoroidal atrophy along the retinal veins bilaterally and bone spicule pigmentation along the nasal and superior temporal venous branches, as well as macular oedema in the left eye. Fluorescein angiography, visual field test, optical coherence tomography and electrophysiological examination were performed, and results were compatible with the diagnosis of pigmented paravenous retinochoroidal atrophy (PPRCA). Treatment with topical dorzolamide and intravitreal bevacizumab in the left eye resulted in poor anatomical and visual response. There is scarce documentation of macular involvement with non-inflammatory unilateral cystoid macular oedema in PPRCA in the literature. Further investigation is required to elucidate the pathogenesis of PPRCA and to properly manage these patients.

Background

Pigmented paravenous retinochoroidal atrophy (PPRCA) is a rare disease characterised by retinal pigment epithelium (RPE) and choroidal atrophy associated with pigment clumping distributed along the retinal veins, usually occurring in a bilateral and symmetric fashion.¹ Most patients are asymptomatic and often diagnosed during a routine examination, as the disease tends to be non-progressive or slowly progressive.^{1 2} The aetiology of PPRCA remains unknown, although genetic, inflammatory and infectious causes have been hypothesised.^{1 2}

There is limited information of this disease published in the literature, mostly arising from small case series. In the present study, we report an unusual asymmetric case of bilateral PPRCA with unilateral pigment clumping and cystoid macular oedema (CMO), with poor anatomical and visual response to intravitreal antiangiogenic treatment.

Case presentation

A 65-year-old man was referred to our Department of Ophthalmology with complaints of blurred vision in the left eye (oculus sinister (OS)) for a month, with no complains in the right eye (oculus dexter (OD)). The patient denied remarkable systemic, ocular or familial history and was not taking any medication. Best-corrected visual acuity (BCVA) in the first visit was 0.6 in the OD and 0.3 in the OS, with a refraction of −0.50D in both eyes. External examination was unremarkable and extraocular motility was full. Anterior segment examination revealed early bilateral nuclear cataracts, without any signs of intraocular inflammation in both eyes. Intraocular pressure was 16 mm Hg in both eyes.

Investigations

Dilated fundus observation revealed asymmetric findings (figure 1). While both eyes presented circumscribed patches of retinochoroidal atrophy along the retinal veins, only the left eye revealed bone spicule pigmentation along the nasal and superior temporal venous branches, as well as macular oedema. No changes were observed in both optic nerve heads the and in the retinal vessel calibre. Peripheral retina was unremarkable bilaterally.

Figure 1.

Asymmetric fundus findings with bilateral areas of retinochoroidal atrophy along the retinal veins and retinal clumping along the retinal veins accompanied by macular oedema in the left eye (right).

Fluorescein angiography (FA) showed transmitted hyperfluorescence consistent with RPE degeneration in both eyes, with more extensive areas of choriocapillaris atrophy and blocked fluorescence in the pigment accumulation areas in the left eye (figure 2). Visual field test by standard automated perimetry with the Humphrey field analyser (HFA) demonstrated a ring scotoma in both eyes, corresponding to the areas of atrophy, with preservation of central fixation (figure 3). Multifocal electroretinogram showed a reduced foveal peak in the OD and an absent foveal peak in the OS (figure 4). The amplitudes of N1, P1 and N2 in the areas between the <2° ring and the 10–15° ring were decreased, with preservation of the more peripheral areas. Electrooculogram revealed abnormal light peak to dark trough in both eyes (104% OD and 108% OS), suggesting bilateral RPE dysfunction.

Figure 2.

Late phase of fluorescein angiography showing annular transmitted hyperfluorescence in both eyes and blocked fluorescence in the pigment accumulation areas in the left eye (right).

Figure 3.

Standard automated perimetry with stimulus V demonstrating a ring scotoma in both eyes with preservation of central fixation.

Figure 4.

Map of P1 wave amplitudes of multifocal electrectroretinogram showing a reduced foveal peak in the right eye (left) and an absent foveal peak in the left eye (right). The amplitudes in the areas between the <2° ring and the 10–15° ring are decreased, while the more peripheral areas are preserved.

Spectral domain optical coherence tomography (SD-OCT) imaging (figure 5) of PPCRA-associated lesions demonstrated outer retinal thinning and intraretinal hyperreflective foci with underlying shadowing corresponding to the pigment clumps. Macular SD-OCT imaging revealed parafoveal inner and outer retinal atrophy better observed in the OD, and CMO with central subfield thickness of 468 µm in the OS. Circumperipapillary retinal nerve fibre layer was preserved in both eyes.

Figure 5.

Spectral domain optical coherence tomography of PPCRA-associated lesions demonstrating outer retinal thinning and intraretinal hyperreflective foci with underlying shadowing corresponding to the pigment clumps (top). Macular imaging revealed parafoveal inner and outer retinal atrophy in both eyes (middle and bottom) and cystoid macular oedema in the left eye (bottom).

General physical examination, as well as laboratory studies including complete blood cell counts, serum electrolytes, serum protein electrophoresis and erythrocyte sedimentation rate were within normal limits. Tuberculin skin test and serological evaluation ruled out tuberculosis, syphilis, toxoplasmosis, cytomegalovirus, systemic lupus erythematosus and rheumatoid arthritis.

Treatment

The patient underwent treatment with topical 2.0% dorzolamide and a loading dose of three intravitreal bevacizumab injections in the OS, followed by pro re nata treatment regimen for 12 months.

Outcome and follow-up

Treatment resulted solely in slight improvement in BCVA (from 0.3 to 0.4), and in central subfield thickness (from 468 to 445 µm). After a 3-year follow-up with fundus examination, FA, HFA and SD-OCT, no clinical progression has been observed in both eyes, with persistence of CMO in the OS.

Discussion

In this report, we present a case of bilateral asymmetric PPRCA with macular involvement. Dilated fundus exam revealed areas of retinochoroidal atrophy along the retinal veins that reached the parafoveal region in both eyes, while there was a more typical PPRCA phenotype in the OS, with retinal clumping along the retinal veins accompanied by more pronounced areas of retinochoroidal atrophy and CMO. FA helped to better delineate the area of atrophy while SD-OCT confirmed parafoveal atrophy in both eyes and CMO. While PPRCA is commonly thought to be bilateral and symmetric, a recent large cohort reported marked interocular asymmetry on structural and functional assessment.²

The areas of retinochoroidal atrophy, typically confined to a paravenous distribution, were more extensive in this case. As the patient only presented at 65, there is no way of telling whether this represents progression of the retinochoroidopathy or severe disease ab initio. Nevertheless, in the 3-year follow-up, there were no changes recorded in the fundus lesions.

Unlike this case, PPRCA is usually asymptomatic. This patient presented with symptoms of blurred vision in the OS due to significant macular oedema and was unaware of the constricted visual fields. While fundus appearance in PPRCA is variable, from mild retinal changes to prominent retinal disturbance, the macula is seldom involved. To the best of our knowledge, there is only one case of mild CMO in PPCRA described in the literature,² which was associated to extensive chorioretinal changes. There is a case report of a secondary (inflammatory) PPRCA which presented with bilateral CMO,³ but its aetiology was probably related to active inflammation and not to the disease per se. Pathogenesis of CMO in PPRCA is not yet understood but it might be similar to the retinitis pigmentosa (RP)-associated CMO,^{2 4} most likely involving failure of the RPE pump mechanism or blood–retinal barrier dysfunction. Neither topical dorzolamide, a common first line treatment in CMO secondary to RP, nor intravitreal antiangiogenic treatment resulted in significant anatomic and functional improvement. As there is no randomised controlled trial regarding the management of rebound CMO in RP,⁵ further studies in this area may help guiding our management of CMO associated with PPRCA.

Macular SD-OCT of the OD demonstrated parafoveal outer and inner retinal thinning, with loss of the ellipsoid and ganglion cell complex layer, which helps to clarify the reduced vision in this eye. Both the submacular choroid and central foveal region maintained their integrity and regular thickness. Classically, the most common changes in macular OCT imaging of PPRCA is attenuation of all outer retinal and choroidal layers.² However, thinning of the inner layers along the region of paravenous retinochoroidal atrophy has also been described,⁶ which showed good correlation with functional loss.

As observed in this case, normal optic nerve heads and retinal vessel calibre is common on PPRCA,² which may help to differentiate it from RP.

Learning points.

• Pigmented paravenous retinochoroidal atrophy (PPRCA) is a rare and poorly understood disorder that tends to be slowly progressive. It usually has good visual prognosis, apart from the rare cases with macular involvement.

• There is scarce documentation in the literature about macular involvement with non-inflammatory unilateral cystoid macular oedema.

• In the presented case, treatment with topical anhydrase inhibitor and intravitreal antiangiogenic resulted in poor anatomic and functional improvement.

• Further investigation is needed to elucidate the pathogenesis of PPRCA to properly manage these patients.