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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 1  |  Issue : 3  |  Page : 535-537

Can there be smoke without fire? Optical coherence tomography angiography has the answer


1 Department of Vitreo-Retinal Services, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Madurai, Tamil Nadu, India
2 Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida

Date of Submission16-Aug-2020
Date of Acceptance28-Jan-2021
Date of Web Publication02-Jul-2021

Correspondence Address:
Dr. Piyush Kohli
Department of Vitreo-Retinal Services, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Madurai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_2654_20

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  Abstract 


Macular edema is typically seen on optical coherence tomography (OCT) as fluid-filled cystic alterations that cause increased retinal thickness. The increased OCT reflectivity within these intraretinal spaces in the outer avascular retina can exhibit flow-like properties when imaged using OCT angiography (OCTA). The motion signal arising from within these intraretinal cavities corresponds to a feature of exudation known as suspended scattering particles in motion (SSPiM). We present multimodal imaging of a patient with SSPiM who underwent partial resolution of this OCTA finding.

Keywords: Diabetes mellitus, hyperreflective fluid (HRF), optical coherence tomography angiography (OCTA), suspended scattering particles in motion (SSPiM), wedge-shaped lesion


How to cite this article:
Vignesh TP, Kohli P, Kumar J, Rosenfeld PJ, Ramasamy K. Can there be smoke without fire? Optical coherence tomography angiography has the answer. Indian J Ophthalmol Case Rep 2021;1:535-7

How to cite this URL:
Vignesh TP, Kohli P, Kumar J, Rosenfeld PJ, Ramasamy K. Can there be smoke without fire? Optical coherence tomography angiography has the answer. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Jul 26];1:535-7. Available from: https://www.ijoreports.in/text.asp?2021/1/3/535/320002



Although macular edema is typically seen on optical coherence tomography (OCT) as hyporeflective cavities within retinal layers, the presence of hyperreflective fluid (HRF) has been reported.[1],[2],[3] Kashani et al. reported that HRF corresponds to a flow-like motion signal on OCT angiography (OCTA), termed as suspended scattering particles in motion (SSPiM).[4] However, not much literature is available on this new entity. We present multimodal imaging of such a patient.


  Case Report Top


A 40-year-old Asian-Indian man presented with complaints of distorted vision in his right eye for four days. He was taking treatment for diabetes mellitus and hypertension for past seven years. He gave no history of recent viral infection or fever. His best-corrected visual acuity (BCVA) was 20/25 in right eye and 20/20 in left eye. Anterior segment examination and intraocular pressures were normal in both his eyes. Fundus examination of the right eye showed a paracentral, well-demarcated, hypopigmented, wedge-shaped intraretinal lesion located inferotemporal to the fovea, extending from the inferior margin of the fovea to the inferior arcade with few hard exudates [Figure 1]a. There were no hemorrhages or cotton wool spots in either eye. The retinal thickness map showed a well-demarcated localized area of edema corresponding to the lesion seen on the fundus photo [Figure 2]a.
Figure 1: (a) Color image of right eye showing paracentral, well-demarcated, hypopigmented, wedge-shaped lesion (yellow circle) inferotemporal to fovea; (b and c) Fundus fluorescein angiography images of right eye showing a small pin-point leak inferonasal to the fovea and within the clinically-evident lesion (black arrow), multiple small microaneurysms around the foveal avascular zone (yellow circle) and patchy, punctate hyperfluorescence nasal to FAZ, with all lesions showing variable leakage in the late phase

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Figure 2: Retinal thickness map (a) showing the edema inferonasal to the fovea corresponding to the lesion seen fundus photo (red colored) at presentation; and (b) resolving edema after one month.

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OCT imaging showed multiple hyperreflective intraretinal cavities within the outer retina between the junction of the Henle fiber layer (HFL) and the outer nuclear layer (ONL) [Figure 3]a and [Figure 3]b and this same hyperreflective fluid (HRF) was also located in the subretinal space just inferior to the fovea [Figure 3]b. This HRF was associated with multiple hyper-reflective foci in and under the fovea [Figure 3]a and [Figure 3]b. OCTA structural scans showed this same HRF and the flow images showed a diffuse signal at the junction of vascular and avascular layer, which represented a property of exudation known as suspended scattering particles in motion (SSPiM) [Figure 4]a and [Figure 4]b. The OCTA en face images revealed no abnormalities in the superficial capillary layer [Figure 4]a while the deeper capillary layer and outer retina showed this HRF and its associated flow signal within the clinically-evident lesion [Figure 4]b, [Figure 4]c, [Figure 4]d. As seen from the intact capillary flow images, there was no evidence of ischemia in any part of the lesion or in any of the retinal layers. Fundus fluorescein angiography (FFA) of the right eye showed a small pin-point leak inferonasal to the fovea with multiple small microaneurysms nasal to the foveal avascular zone (FAZ) associated with patchy, punctate hyperfluorescence in the early phase and the late phase showed diffuse leakage from these same areas [Figure 1]b and [Figure 1]c. No pathology was noted by exam or imaging in the left eye. The arm-to-retina and arteriovenous transit times were normal in both the eyes. There was no evidence of any capillary non-perfusion areas or perivascular leak in either eye.
Figure 3: Optical coherence tomography line scans (a and b) at presentation showing hyperreflective fluid (HRF, arrow) (a) at the junction of the Henle retinal layer and the outer nuclear layer along with hyperreflective foci (arrow head), and (b) in the subretinal space just inferior to the fovea; and (c) after one month, resolution of HRF with an increase in hyper reflective foci in the outer retinal layers as well as inner segment/outer segment (IS/OS) defect (line)

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Figure 4: Optical coherence tomography angiography structural scan with corresponding en face images. (a-d) At presentation showing suspended scattered particle in motion (SSPiM) at the junction of the vascular and avascular layers (yellow color dots) with (a) normal superficial capillary layer, (b) specks of hyperreflective signals in the deep capillary layer, and (c and d) intense hyperreflective signals in the avascular retinal layer throughout clinical lesion including the foveal avascular zone; and (e and f) after one month, resolving SSPiM with decreased hyperreflective signals in the deep capillary layer and the avascular layer

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Further evaluations showed blood pressure 150/80mmHg, hemoglobin 14.6 g/dL, random blood sugar 427 mg/dL, glycosylated hemoglobin 12.8%, triglycerides 490 mg/dL, total cholesterol 286 mg/dL, low-density lipoprotein 157 mg/dL, very low-density lipoprotein 98 mg/dL and erythrocyte sedimentation rate 16 mm/h. Complete blood count, peripheral blood smear, renal function tests, carotid Doppler, and echocardiography did not reveal any pathology. He was diagnosed to have SSPiM secondary to uncontrolled diabetes with his macular edema being a manifestation of an early retinal vein occlusion as the macular edema respected the horizontal raphe. He was advised to maintain a strict metabolic control.

One month later, his symptoms improved and BCVA improved to 20/20. The intensity of the hypopigmented lesion seen on fundus examination became less apparent [Figure 3]c, with the corresponding retinal thickness map revealing resolving edema [Figure 2]b. The amount of intraretinal HRF on OCT imaging decreased, the subretinal HRF resolved [Figure 3]c, and the SSPiM signal associated with the HRF diminished along with the fluid. [Figure 4]e and [Figure 4]f. Hyper-reflective foci increased in number along with the appearance of an inner segment/outer segment (IS/OS) defect [Figure 3]c.


  Discussion Top


Kashani et al. found that the patients with hyperreflective cavities of intraretinal edema showed a corresponding diffuse OCTA flow signal that was not associated with blood flow, and this OCTA feature of exudative retinal diseases was termed SSPiM. They proposed that  Brownian motion More Details of particulate material within the pockets of intraretinal edema could be responsible for this signal on OCTA. They reported that these lesions appear in patients with exudative maculopathy like diabetic retinopathy, retinal vein occlusions, and neovascular age-related macular degeneration and are associated with poor prognosis.[4],[5]

Our patient presented with a paracentral, well-demarcated, hypopigmented, wedge-shaped intraretinal lesion that we thought would be paracentral acute middle maculopathy (PAMM); however, OCTA and FFA in our case were not consistent with PAMM.[6],[7] The hyperreflective signals along the deep capillary and outer retinal layers were most consistent with the type of signal seen with exudation and referred to as SSPiM.

SSPiM is an OCTA finding with a predilection for regions between vascular and avascular layers such as the HFL, ONL, and FAZ. Since SSPiM is associated with exudation, it is not surprising that the hyper-reflective foci, which are associated with hard exudates, increase in number as the SSPiM resolves. Although the earlier authors have reported a lack of SSPiM findings in the subretinal space, however, in our patient, SSPiM was present in the subretinal space apart from its presence in HFL and ONL.


  Conclusion Top


SSPiM is a novel OCT-A finding seen in patients with exudative maculopathy. With the increased use of OCT-A in evaluation of patients, more details about this finding will be appreciated.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Liang MC, Vora RA, Duker JS, Reichel E. Solid-appearing retinal cysts in diabetic macular edema: A novel optical coherence tomography finding. Retin Cases Brief Rep 2013;7:255-8.  Back to cited text no. 1
    
2.
Kashani AH, Lee SY, Moshfeghi A, Durbin MK, Puliafito CA. Optical coherence tomography angiography of retinal venous occlusion. Retina 2015;35:2323-31.  Back to cited text no. 2
    
3.
Matsunaga DR, Yi JJ, De Koo LO, Ameri H, Puliafito CA, Kashani AH. Optical coherence tomography angiography of diabetic retinopathy in human subjects. Ophthalmic Surg Lasers Imaging Retina 2015;46:796-805.  Back to cited text no. 3
    
4.
Kashani AH, Green KM, Kwon J, Chu Z, Zhang Q, Wang RK, et al. Suspended scattering particles in motion: A novel feature of OCT angiography in exudative maculopathies. Ophthalmol Retina 2018;2:694-702.  Back to cited text no. 4
    
5.
Ahn J, Han S, Ahn SM, Kim SW, Oh J. Clinical implications of suspended scattering particles in motion observed by optical coherence tomography angiography. Sci Rep 2020;10:15.  Back to cited text no. 5
    
6.
Mrejen S, Le HM, Nghiem-Buffet S, Tabary S, Quentel G, Cohen SY. Insights into perifoveal exudative vascular anomalous complex. Retina 2020;40:80-6.  Back to cited text no. 6
    
7.
Bhavsar KV, Lin S, Rahimy E, Joseph A, Freund KB, Sarraf D, et al. Acute macular neuroretinopathy: A comprehensive review of the literature. Surv Ophthalmol 2016;61:538-65.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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