|Year : 2016 | Volume
| Issue : 3 | Page : 171-175
Tomographic features of idiopathic polypoidal choroidal vasculopathy using spectral domain OCT
Rajashree Nambiar, S Manoj, Unnikrishnan Nair, Sanika Jain
Department of Vitreoretinal Services, ChaitAnya Eye Hospital and Research Centre, Kesavadasapuram, Thiruvananthapuram, Kerala, India
|Date of Web Publication||2-May-2017|
Chaitanya Eye Hospital and Research Centre, Vitreoretinal Services Kesavadasapuram, Thiruvananthapuram - 695 004, Kerala
Source of Support: None, Conflict of Interest: None
Purpose: To study the tomographic features of idiopathic polypoidal choroidal vasculopathy (IPCV) diagnosed on indocyanine green (ICG) angiogram using spectral domain optical coherence tomography (SDOCT).
Design: This was a retrospective observational case series.
Materials and Methods: Spectral domain optical coherence tomography (SD OCT) features of 50 eyes of 50 consecutive patients diagnosed as idiopathic polypoidal choroidal vasculopathy (IPCV) between January 2013 to January 2015 on ICG angiograms were studied. A qualitative analysis based on various tomographic features corresponding to the polypoidal lesions and branching vascular network on Spectrailis OCT was studied. Polyps were localized to subfoveal and juxtafoveal areas. These were later compared with SDOCT features of 15 eyes of 15 consecutive patients newly diagnosed as occult choroidal neovascular membrane (CNVM) on FFA/ICG.
Results: Of the 50 eyes, sharp peak pigment epithelial notch (PED) was present in 49 eyes (98%); PED notch in 49 eyes (98%); a visible hyporeflective lumen with hyperreflective lesions adherent to the outer surface of the RPE in 48 eyes (96%), multiple PED in 44 eyes (80%), and diffuse PED in 44 eyes (80%); intraretinal hyperreflective dots representing hard exudates were seen in 44 eyes (88%). Surrounding OCT features such as intraretinal hyperreflective dots represent hard exudates, Cystoid macular edema and subretinal fluid were seen in 44 eyes (88%). Sub-RPE features such as PED with sheaths of internal reflectivity – branching vascular network in 19 eyes (38%) and prominent Bruchs membrane and surfacing of choroidal vessels was seen in 18 eyes (36%). At least 3 of the abovementioned OCT features were seen in all of the eyes diagnosed as PCV. The height of the PED ranged from 138–1300 μ (median = 422.2 μ). Of the 15 eyes, 80% showed presence of FVPED; multiple PED were seen in 33.3%; intraretinal hard exudates in 66.7%, and notch PED in 6.7%. Hyporeflective lumen with hyperreflective lesion under RPE was not seen in any of the eyes. The height of PED ranged from 118–339 μ (median = 164.28 μ).
Conclusions: SDOCT-based features mentioned above allows detection of IPCV and differentiate it from occult CNVM. Our results suggest that SDOCT may be a useful noninvasive tool compared to ICG in detecting PCV, especially in places where ICG is not available or is contraindicated.
Keywords: Choroidal neovascular membrane, idiopathic polypoidal choroidal vasculopathy, indocyanine green angiography, optical coherence tomography, pigment epithelial detachment
|How to cite this article:|
Nambiar R, Manoj S, Nair U, Jain S. Tomographic features of idiopathic polypoidal choroidal vasculopathy using spectral domain OCT. Kerala J Ophthalmol 2016;28:171-5
|How to cite this URL:|
Nambiar R, Manoj S, Nair U, Jain S. Tomographic features of idiopathic polypoidal choroidal vasculopathy using spectral domain OCT. Kerala J Ophthalmol [serial online] 2016 [cited 2017 Aug 23];28:171-5. Available from: http://www.kjophthal.com/text.asp?2016/28/3/171/205432
| Introduction|| |
Polypoidal choroidal vasculopathy (PCV) was initially described as a distinct choroidal vascular abnormality characterized by presence of aneurysmal polypoidal lesions in choroidal vasculature with or without branching vascular network. Indocyanine green angiography is the gold standard in diagnosis. Presence of single or multiple focal areas of hyperfluorescence arising from choroidal circulation which are called polyps within first6 minutes with or without Branching vascular network. Early time-domain optical coherence tomography (TD-OCT) studies showed that the polypoidal lesions as well as the BVN as seen on ICGA were associated with “atypical” pigment epithelial detachments (PEDs), However, TD-OCT has a poor definition of the outer retinal layers, and while the findings are suggestive of a sub-retinal pigment epithelial (sub-RPE) location of PCV, they are not confirmatory. Spectral-domain optical coherence tomography (SD-OCT) has a superior ability to resolve the outer retinal layers and may offer an opportunity to better define the location of PCV lesions in vivo4. In this study, we examined patients with a typical presentation of PCV both clinically and angiographically, using SD-OCT in an effort to characterize the tomographic features of this disease.
Aim of study
To study the tomographic features of idiopathic polypoidal choroidal vasculopathy (IPCV) using spectral domain optical coherence tomography (SDOCT).
| Materials and Methods|| |
This was a retrospective observational case series. SDOCT tomographic features of 50 eyes of 50 consecutive patients diagnosed as IPCV between January 2013 to January 2015 on indocyanine green (ICG) angiograms were studied. A qualitative analysis based on various tomographic features corresponding to the polypoidal lesions and branching vascular network on Spectralis OCT (Heidelberg Engineering Gmbh) using posterior pole raster acquisition protocol was studied. Polyps were localized to subfoveal and juxtafoveal areas. These were later compared with SDOCT features of 15 eyes of 15 consecutive patients newly diagnosed as occult choroidal neovascular membrane (CNVM) on FFA/ICG. Statistical analysis was done using Chi-square test.
| Results|| |
Fifty eyes of 50 patients diagnosed as IPCV on ICG were retrospectively evaluated (27 males; 23 females) (mean age 65.6; SD ± 9.7 years; median 64.5 years) were included. Forty-six of the patients were hypertensive and 38% of the patients were diabetic.
Of the second group of the 15 eyes diagnosed as occult CNVM on FFA/ICG, 8 were males and 7 were females (Mean age 73.14; SD ± 8.55; Median age 65.5 years). Patients with IPCV were at least 10 years younger than occult group. A total of 26.7% of the patients were hypertensive, whereas 40% were diabetic.
Assessment of the spectral domain optical coherence tomography features of polypoidal choroidal vasculopathy
Of the 50 eyes sharp peak PED was present in 49 eyes (98%); notched PED in 49 eyes (98%); multiple peaked PED (80%), diffuse PED (80%), a visible hyporeflective lumen with hyperreflective lesions adherent to the outer surface of the RPE in 48 eyes (96%). Surrounding OCT features such as intraretinal hyperreflective dots represent hard exudates. Cystoid macular edema and subretinal fluid were seen in 44 eyes (88%). Subretinal pigment epithelial features such as PED with sheaths of internal reflectivity-BVN in 19 eyes (38%), and prominent Bruchs membrane and surfacing of choroidal vessels was seen in 18 eyes (36%) [Figure 1]. At least 3 of the abovementioned OCT features were seen in all of the eyes diagnosed as PCV. The height of the PED ranged from 138–1300 μ (median = 422.2 μ).
Assessment of the spectral domain optical coherence tomography features of occult choroidal neovascular membrane
Of the 15 eyes, 80% showed presence of fibrovascular PED; multiple PED were seen in 33.3%; intraretinal hard exudates in 66.7%, and notched PED in 6.7%. Hyporeflective lumen with hyperreflective lesion under RPE was not seen in any of the eyes [Figure 2]. The height of PED ranged 138–1300 μ (median = 422.2 μm), which was higher than the comparison group of occult CNVM, which ranged 118–339 μ (median = 164.28 μ) [Figure 3].
|Figure 3: Graph showing comparison between Height of PED in the study groups|
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Between the groups except for the presence of intraretinal hyperreflective dots representing hard exudates (P = 0.124), there was statistically significant difference between all the other tomographic features of PCV and occult CNVM (P < 0.05) [Figure 4].
|Figure 4: Comparison of qualitative variables in PCV and occult CNVM analysed by Chi- square test|
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| Discussion|| |
PCV is characterized by recurrent serosanguinous detachment of RPE; at present, ICG is considered the gold standard for the diagnosis as it allows visualization of BVN and its polypoidal lesions.
As ICG is an invasive technique with possible complications, a quest has been ongoing to find newer and better modalities for diagnosis. Principal among these has been the newer imaging technique of SDOCT. The ICG images have speculated that the vascular abnormalities in PCV represent a peculiar form of neovascularization located beneath the RPE. The angiogram can, however, not clearly delineate the precise locations of sub-RPE lesions. The histological examinations in some surgical specimens did show dilated venules and arterioles under Bruch's membrane or fibrovascular tissue within Bruch's membrane.
OCT is a noninvasive tool which works on the principle of interoferometry capturing light reflecting from the plane of interest to produce high-resolution images enabling near histologic visualization of anatomical features of PCV. The RPE is represented on OCT images as a highly reflective line. The polypoidal lesions appear as sharp protrusions of the RPE with moderate reflectivity beneath the RPE line. The conventional OCT poorly delineates these sub-RPE lesions because of its limited axial resolution of approximately 10 μm. The higher resolution OCT such as EDI provide better delineation of the sub-RPE lesions.
In this study, in the 50 eyes which were diagnosed as PCV on ICG, we studied different tomographic features on SDOCT. These features included sharp peak PED; PED notch; multiple PED; diffuse PED; a visible hyporeflective lumen with hyperreflective lesions adherent to the outer surface of the RPE; and surrounding OCT features such as intraretinal hyperreflective dots representing hard exudates, cystoid macular edema, subretinal fluid, and subretinal pigment epithelial features. These features were compared to various tomographic features of occult CNVM and their statistical significance were analyzed by chi square test (P < 0.05).
Of these features, one of the earliest tomographic signs described in PCV has been a steep sharp peak like elevation of the RPE with underlying moderate reflectivity within the peak [Figure 5]. DeSalvo et al. noticed this feature in 91.9% of the eyes with PCV whereas 7.1% of the eyes with occult CNVM showed this feature. In our study, this feature was seen in 98% of the eyes with PCV, while this was not seen in any of eyes with Occult CNVM (P < 0.001).
The tomographic notch(notched PED) appears as V shaped depression between two PEDS [Figure 6]. Tsujikawa et al. found tomographic notch in 57% of the eyes with PCV and proved that the hyperreflectivity under the dome corresponded to polypoidal lesion seen by ICG [Figure 7]. The reason for hyperreflectivity under the dome being the polyps have increased exudate and hence the fluid from the lesion infiltrate under the polyps and the lesions detach from the bruchs membrane appearing located inside the pigment epithelial detachment. In the current study tomographic notch was seen in 98%of the eyes with PCV and hyperreflectivity under the PED was seen in 96%of the eyes. This was comparable with the study by Desalvo et al. where this feature was seen in 100% of the eyes with PCV.
|Figure 6: SD OCT image shows polypoidal structures which are divided by septa correlating with angiographic findings of PED notch|
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The presence of multiple PED, diffuse PED, and surrounding OCT features such intraretinal hyperreflective dots were also studied, which represent hard exudates over the hyporeflective subretinal fluid [Figure 8]. In our study, 80% of eyes showed multiple PEDs, which were statistically significant in comparison to the occult CNVM cases (P < 0.002). However, the other feature of intraretinal hyperreflective dots were seen in 88% of PCV versus 66.6% of occult CNVM did not show statistical significance (P = 0.124). This was comparable with other studies.
|Figure 8: Surrounding OCT features including intraretinal hyperreflective dots representing hard exudates,CME and SRF|
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In 15 eyes with occult CNVM, 80% showed presence of fibrovascular PED (FVPED) on OCT while none of the cases of PCV showed this feature [Figure 9]. On FFA/ICG, all these cases showed irregular leakage, which was suggestive of FVPED and hot spot compatible with occult CNVM. These were described by some as shallow PED and no hyporeflective lumen in occult CNVM cases.
The height of PED ranged 138–1300 μ (median = 422.2 μm), which was higher than the comparison group of occult CNVM which ranged 118–339 μ (median = 164.28 μ). Our study showed that the height of PED in PCV group was higher than occult group as in other studies.
Sub-RPE features such as multilayering under the PED could represent BVN (38%) and prominent Bruchs membrane (36%) and surfacing of choroidal vessels indicating associated reactive changes was statistically significant comparable to other studies [Figure 10] and [Figure 11].,
|Figure 10: SUB RPE FEATURES like PED with sheaths of internal reflectivity - BVN|
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|Figure 11: SD OCT image showing Prominent Bruchs membrane and surfacing of choroidal vessels|
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Our study had a few limitations including that it was a retrospective study and the number of patients were small. This study only deals with two conditions – PCV and occult CNVM. Other retinal conditions such as CSR, classic CNV showing PED, and their distinguishing features were not studied. Role of EDI in diagnosis of PCV has a major role but in this study this modality was used in a small number of patients and was not statistically powered to give any significance.
| Conclusions|| |
Sharp peak PED, notched PED, hyperreflective lesion at summit of the PED, diffuse PED, and sub-RPE changes studied on SDOCT were found to be statistically significant in distinguishing PCV from occult CNVM. Using the abovementioned OCT criteria, PCV can be suspected based on the nature of PED and other OCT features without ICG angiography, which is not as widely used as FFA. However, ICG angiogram is essential to confirm diagnosis in suspicious and presumed PCV when contemplating PDT or combination therapy is mandatory.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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