Delineation of capillary dropout in the deep retinal capillary plexus using optical coherence tomography angiography in a patient with Purtscher's retinopathy exhibiting normal fluorescein angiography findings: a case report

Retinal ischemic cascade: New insights into the pathophysiology and imaging findings

Retinal ischemia gives rise to a complex spectrum in which the cumulative profile of ischemia of the middle and inner retina can be highly variable. We reviewed the current knowledge on paracentral acute middle maculopathy (PAMM) pathophysiology and accompanying risk factors, the middle and inner retinal vasculature and blood flow, and the vulnerability of the middle retina in vaso-occlusive disorders. The inner nuclear layer (INL) is easily affected by slight degrees of retinal hypoperfusion and ischemia. INL infarction starts at perivenular sites, manifesting as skip PAMM lesions and a fern-like appearance in cross-sectional and en face views, respectively. With horizontal progression, INL infarction may develop into diffuse globular PAMM. If vertical progression occurs, the entire middle and inner portions of the retina can be affected. Transmural infarction of the middle and inner retina would be at the end of this spectrum. This gradient of ischemic progression resembles an ischemic cascade. We review the evidence supporting the term "retinal ischemic cascade," which encompasses a broad continuum of manifestations with roots in middle retinal infarction. With this terminology, variations in spatial and temporal progression and resolution of ischemia can also be delivered; it further enables addressing the possible associations between the middle and inner retinal ischemic patterns.

Choriocapillaris alteration in patients with paracentral acute middle maculopathy

PURPOSE

To evaluate with optical coherence tomography angiography the status of the choriocapillaris in the eyes of patients with resolved paracentral acute middle maculopathy (PAMM).

METHODS

Nine patients with unilateral resolved PAMM, 14 age-matched healthy individuals, and 16 age-matched patients with unilateral retinal vein occlusion (RVO) were included. The choriocapillaris flow area, and the number of choriocapillaris flow voids was compared between the eyes of healthy individuals, both eyes of the PAMM patients, and the fellow eyes of unilateral RVO patients.

RESULTS

The number of choriocapillaris flow voids in the unaffected eyes of PAMM patients was statistically significantly higher than in the eyes of healthy individuals (p < 0.001) and in the fellow eyes of unilateral RVO patients (p = 0.022). The choriocapillaris flow area in the unaffected eyes of PAMM patients was statistically significantly lower than in the eyes of healthy individuals (p < 0.001) and in the fellow eyes of unilateral RVO patients (p = 0.019). There was no difference in the status of the choriocapillaris between two eyes of PAMM patients.

CONCLUSION

Eyes of patients with resolved PAMM have a substantial decrease of choriocapillaris perfusion.

Paracentral acute middle maculopathy and the organization of the retinal capillary plexuses

The retinal capillary vasculature serves the formidable role of supplying the metabolically active inner and middle retina. In the parafoveal region, the retinal capillary plexuses (RCP) are organized in a system of three capillary layers of varying retinal depths: the superficial capillary plexus (SCP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP). While the dynamic flow through these plexuses is complex and not completely understood, current research points to a hybrid model that includes both parallel and in series components in which blood flows in a predominantly serial direction between the superficial vascular complex (SVC) and deep vascular complex (DVC). Each capillary plexus autoregulates independently, so that under most conditions the retinal vasculature supplies adequate blood flow and oxygen saturation at varying depths despite diverse environmental stressors. When the flow in the deep vascular complex (i.e. ICP and DCP) fails, an ischemic lesion referred to as Paracentral Acute Middle Maculopathy (PAMM) can be identified. PAMM is an optical coherence tomography (OCT) finding defined by the presence of a hyperreflective band at the level of the inner nuclear layer (INL) that indicates INL infarction caused by globally impaired perfusion through the retinal capillary system leading to hypoperfusion of the DVC or specifically the DCP. Patients present with an acute onset paracentral scotoma and typically experience a permanent visual defect. Lesions can be caused by a diverse set of local retinal vascular diseases and systemic disorders. PAMM is a manifestation of the retinal ischemic cascade in which the mildest forms of ischemia develop at the venular end of the DCP, i.e. perivenular PAMM, while more severe forms progress horizontally to diffusely involve the INL, and the most severe forms progress vertically to infarct the inner retina. Management is targeted toward the identification and treatment of related vasculopathic and systemic risk factors.

Paracentral acute middle maculopathy-review of the literature

Paracentral acute middle maculopathy (PAMM) is a recently identified spectral-domain optical coherence tomography (SD-OCT) finding characterized by a hyper-reflective band spanning the inner nuclear layer (INL), which typically evolves to INL atrophy in later stages. Typical clinical features include the sudden onset of one or multiple paracentral scotomas, normal or mild reduction in visual acuity, and a normal fundus appearance or a fundus with a deep grayish lesion. Although its pathophysiology is not yet fully understood, ischemia at the level of the intermediate and deep capillary plexa has been demonstrated to play a major role. Since its first description, an increasing number of publications on PAMM have been published in ophthalmology scientific journals. The purpose of this study is to provide a review of the current literature on PAMM.

[Spectrum of diseases associated with paracentral acute middle maculopathy]

Paracentral acute middle maculopathy (PAMM) is a rare disease affecting middle layers of the central retina that is seen as a focal hyperreflective band-like lesion on optical coherence tomography. Paracentral acute middle maculopathy is associated mainly with vascular diseases. Optical coherence tomography angiography (OCTA) findings confirm the ischemic nature of paracentral acute middle maculopathy.

PARACENTRAL ACUTE MIDDLE MACULOPATHY IN PURTSCHER RETINOPATHY

PURPOSE

To describe paracentral acute middle maculopathy associated with Purtscher retinopathy, particularly in Purtscher flecken lesions as a retinal complication in a case secondary to fractures of long bones.

METHODS

Case report.

RESULTS

A 16-year-old boy with bilateral paracentral scotomata presented with bilateral paracentral acute middle maculopathy as part of Purtscher retinopathy in both eyes as consequence of tibia and fibula fractures.

CONCLUSION

Paracentral acute middle maculopathy is one of the optical coherence tomography findings in Purtscher retinopathy.

Electric shock induced Purtscher-like retinopathy

The most common ocular manifestation following electric shock injury is the development of cataract. Retinal manifestations can vary from development of macular holes to retinal detachments. Purtscher-like retinopathy following electrical injury has not been reported till date. We hereby present a case of a 19-year-old electrician who presented with grossly reduced vision in the right eye of 2 months following an electric shock. The fundus of the right eye showed macular ischemic degeneration, occluded vessels, cotton-wool spots, and hemorrhages. Optical coherence tomography angiography revealed presence of capillary drop-out in the para-foveal region, which was more pronounced in the deep capillary plexus. Electric shock injury can lead to a clinical picture simulating Purtscher's retinopathy. The electrical injury leads to a more extensive damage to the deep capillary plexus as compared with the superficial plexus.

Multimodal imaging including optical coherence tomography angiography in patients with type B Niemann-Pick disease

PURPOSE

To evaluate accumulation patterns of deposits in retinal layers of type B Niemann-Pick patients by multimodal imaging.

METHODS

Seven patients with type B Niemann-Pick disease were included in this study. All participants underwent a complete ophthalmologic evaluation, high-resolution digital colour imaging, spectral-domain optical coherence tomography, blue light fundus autofluorescence and optical coherence tomography angiography (OCTA).

RESULTS

We demonstrated different accumulation patterns in the retinal ganglion cell layer, the retinal nerve fibre layer and the subfoveolar region by multimodal imaging. Local retinal capillary nonflow areas in the superficial plexus, increased vascular tortuosity and deformed foveal avascular areas were shown in OCTA scans.

CONCLUSION

Multimodal imaging including OCTA is a useful technique for the identification of different types of accumulation patterns, diagnosis and follow-up of type B Niemann-Pick patients.

Assessment of capillary dropout in the superficial retinal capillary plexus by optical coherence tomography angiography in the early stage of diabetic retinopathy

Background

To assess capillary dropout in the superficial retinal capillary plexus (SCP) by optical coherence tomography angiography (OCTA) in the early stage of diabetic retinopathy (DR).

Methods

This study was a cross-sectional observational study. Patients that underwent OCTA examinations in our hospital between November 2015 and May 2016 were included in the study. The subjects were divided into two groups: A) normal controls (41 eyes of 41 subjects) and B) the DR patients (49 eyes of 49 patients with mild non-proliferative DR (NPDR)). The retinal thickness and SCP vessel density were analyzed using built-in software in nine sections of the macular area; whole scan area; fovea; parafovea; and sub-sections of the parafovea, superior-hemi, inferior-hemi, temporal, superior, nasal, and inferior. The correlation between vessel density and retinal thickness was also analyzed.

Results

The SCP density was significantly lower (P < 0.05) in mild NPDR patients than in normal controls in all areas, with the exception of the fovea (P > 0.05). In the parafovea, superior-hemi, inferior-hemi, temporal, and nasal sectors of group B, the SCP density was negatively correlated with the corresponding retinal thickness (P < 0.05). Specifically, as the SCP density decreased, retinal thickness increased.

Conclusions

In the early stage of NPDR, retinal capillary dropout and retinal thickness changes can be clearly captured and analyzed by OCTA. The results confirm a negative correlation between vessel density and retinal thickness in diabetic patients. This noninvasive technique could be applied for DR detection and monitoring. Further study with a larger sample size is warranted.

Purtscher-like retinopathy associated with squamous cell carcinoma of the cervix

PURPOSE

To describe a previously unreported case of Purtscher-like retinopathy secondary to severe acute renal failure associated with squamous cell carcinoma of the cervix.

METHODS

This is a case report.

RESULTS

A 31-year-old female presented with a week history of acute abdominal pain, vomiting and severe renal failure followed by a sudden onset of bilateral visual loss. Vision was hand movement in either eye with central scotoma. Ophthalmic examination demonstrated bilateral retinal thickening and whitening with intraretinal hemorrhages localized to the peripapillary area, consistent with the diagnosis of Purtscher-like retinopathy. Further systemic examination revealed bilateral hydronephrosis secondary to underlying undiagnosed cervical carcinoma. Patient was treated with a short course of high-dose steroids. At 2 months, patient vision remained poor despite the resolution of retinal edema and hemorrhages.

CONCLUSIONS

This case serves as the first report of Purtscher-like retinopathy secondary to acute renal failure associated with cervical carcinoma, expanding the list of causes of Purtscher's or Purtscher-like retinopathies. In the presence of significant uremia and absence of previously known association, the authors postulate that the sudden surge of uremia causes increase of endothelin-1 (a potent vasoconstrictor), resulting in downstream endothelin-induced vasculopathy with subsequent occlusion of the pre-capillary arteriolar network.