Purpose
To describe optical coherence tomographic (OCT) angiography findings in chronic central serous chorioretinopathy (CSC), and to characterize their OCT B-scans by means of the split-spectrum amplitude-decorrelation angiography algorithm.
Design
Evaluation of an imaging technique in a cohort of patients.
Methods
Fluorescein (FA) and indocyanine green (ICGA) angiography (Heidelberg Spectralis, Heidelberg, Germany), OCT angiography, and OCT angiography with the split-spectrum amplitude-decorrelation angiography algorithm (XR Optovue, Fremont, California, USA) were performed. A qualitative analysis of the entire imaging data was done.
Results
Twelve eyes of 10 patients were included. Mean visual acuity was 20/30. All eyes presented findings consistent with chronic CSC (lasting more than 6 months) on biomicroscopic examination, autofluorescence, FA, ICGA, and OCT. ICGA showed the characteristic choroidal hyperpermeability, while there was no evidence of choroidal neovascularization (CNV). OCT B-scans showed 2 distinct profiles of the retinal pigment epithelium (RPE): a slight RPE detachment with small undulations was evident in 7 of 12 eyes, while 5 eyes presented a flat RPE profile. OCT angiography in 7 eyes (58%) revealed the presence of a distinct CNV corresponding to the ICGA hyperpermeability. The qualitative analysis of the OCT B-scans compared to the OCT angiographic images demonstrated that the CNV corresponded to the small undulations within the slight RPE detachment, confirming its vascularized nature. On the contrary, OCT angiography showed a normal choroidal circulation in the remaining 5 eyes (42%) with a flat RPE profile.
Conclusions
OCT angiography allows detection of CNV in chronic CSC not visible with other imaging techniques. CNV corresponds to the small undulating RPE detachment on B-scan. This might allow an appropriate treatment resulting in a better visual outcome.
Chronic central serous chorioretinopathy (CSC) is characterized by widespread alterations in the retinal pigment epithelium (RPE) that are associated with serous detachment of the neurosensory retina.
Fluorescein angiography (FA) shows 1 or multiple leaking points and diffuse alterations at the level of the RPE. Indocyanine green (ICG) angiography reveals hyperfluorescent areas that correspond to leaking points, and the choroid appears partly hypofluorescent owing to RPE atrophy and partly hyperfluorescent owing to the choriocapillary hyperpermeability.
Optical coherence tomographic (OCT) examinations reveal subretinal fluid and an irregular profile of the internal margin of the neurosensory retinal detachment secondary to a thickening and elongation of photoreceptor outer segments. A double-layer sign may appear with an undulating RPE profile, a hyporeflective middle layer, and an intact or slightly thickened Bruch membrane.
Recently, new imaging technologies have developed that allow for new insights in the visualization of normal and pathologic vascularization. Specifically, software called “split-spectrum amplitude-decorrelation angiography” allows for the visualization of both the inner and outer retinal vascular plexi and the choriocapillary layer without the need for dye injection. It is usually difficult to visualize these vascular complexes with FA and ICG angiography. This algorithm enables the noninvasive visualization of vessels in the posterior part of the eye with a segmentation of the different layers using the “en face” OCT modality.
The purposes of this study were to describe OCT angiographic findings in chronic CSC and to characterize the B-scan OCT via split-spectrum amplitude-decorrelation angiography and en face modality findings in the same cohort.
Patients and Methods
This study was approved by the Institutional Review Board of the Fédération France Macula, informed consent was obtained from all of the patients, and all research and data collection complied with the Declaration of Helsinki.
We enrolled consecutive cases of chronic CSC seen at our clinic, which is the third-largest referral center for retinal pathologies, between June 2014 and December 2014.
Every patient underwent a complete ophthalmic examination that included the following: a best-corrected visual acuity measurement with the Early Treatment Diabetic Retinopathy Study (ETDRS) charts, anterior segment examination, intraocular pressure measurement by applanation tonometry, and dilated fundus biomicroscopy. Fluorescein and ICG angiography (Heidelberg Spectralis, Heidelberg, Germany), spectral-domain OCT (SD OCT), and OCT angiography using the split-spectrum amplitude-decorrelation angiography algorithm were also performed (RTVue XR Avanti with AngioVue; Optovue Inc, Fremont, California, USA). The instrument used in the OCT angiography was based on the Optovue RTVue XR Avanti (Optovue, Inc) and was used to obtain amplitude-decorrelated angiography images. This instrument has an A-scan rate of 70 000 scans per second and uses a light source centered at 840 nm and a bandwidth of 50 nm. Each OCT angiography volume contained 304 × 304 A-scans with 2 consecutive B-scans that were captured at each fixed position before proceeding to the next sampling location. Split-spectrum amplitude-decorrelation angiography was used to extract the OCT angiography information. Each OCT angiography volume was acquired over 3 seconds, and 2 orthogonal OCT angiography volumes were acquired to perform motion correction to minimize the motion artifacts arising from microsaccades and fixation changes. The angiography information is displayed as the average of the decorrelation values when viewed perpendicularly through the thickness being evaluated. The modifications in reflectivity are directly linked to blood flow. The horizontal and vertical scans were combined with an algorithm that compensates for the motion of the patient’s eyes (ie, motion correction technology [MCT]) to create a 3-dimensional volume of the retinal vascularization. The en face imaging enabling us to focus on the superficial vessels by choosing the inner limiting membrane as a reference or to go deeper to focus on new vessels by choosing the RPE layer as a reference. A flat reference plan that makes the C-scan independent of the patient’s retina is also available.
A qualitative analysis and comparisons of the entire imaging data set were conducted. Regarding the OCT angiography, in all cases, we set the reference at the level of the RPE. Two retinal specialists (M.Q.E.M. and C.M.E.) independently read the B-scans and OCT angiographic images to determine the presence of choroidal neovascularization (CNV) and its location in relation to the pigment epithelium detachment (PED).
Results
Twelve eyes from 10 patients (5 women and 5 men) were included. The patients ranged in age from 49 to 64 years with a mean age of 54.6 years. All of the patients were white ( Table ). The diagnoses of CSC were already established in 5 patients and newly formulated in the other 5 patients based on clinical history and fundus and angiographic features. Six patients had histories of steroid use. All patients presented with a history of long-lasting (>6 months) visual impairment. The ETDRS best-corrected visual acuities ranged from 20/40 to 20/20 (mean 20/30).
| Eye # | Sex | Age (Years) | Visual Acuity (Snellen) | Choroidal Thickness (μm) | Subretinal Fluid | RPE Profile | OCT Angiography |
|---|---|---|---|---|---|---|---|
| 1 | Female | 53 | 20/40 | 530 | Yes | Undulated | Choroidal neovascularization |
| 2 | Male | 62 | 20/40 | 325 | Yes | Undulated | Choroidal neovascularization |
| 3 | Female | 52 | 20/30 | 570 | Yes | Undulated | Choroidal neovascularization |
| 4 | Female | 52 | 20/20 | 470 | No | Undulated | Choroidal neovascularization |
| 5 | Male | 54 | 20/20 | 440 | Yes | Flat | No choroidal neovascularization |
| 6 | Female | 64 | 20/40 | 315 | Yes | Flat | No choroidal neovascularization |
| 7 | Male | 50 | 20/40 | 490 | Yes | Flat | No choroidal neovascularization |
| 8 | Female | 61 | 20/30 | 228 | No | Undulated | Choroidal neovascularization |
| 9 | Male | 50 | 20/30 | 490 | Yes | Flat | No choroidal neovascularization |
| 10 | Male | 49 | 20/30 | 380 | Yes | Flat | No choroidal neovascularization |
| 11 | Female | 54 | 20/30 | 280 | Yes | Undulated | Choroidal neovascularization |
| 12 | Female | 54 | 20/20 | 290 | No | Undulated | Choroidal neovascularization |
The anterior segment examinations did not reveal any relevant features.
The biomicroscopic fundus examinations revealed serous retinal detachment at the posterior pole, particularly in the macular region, and multiple zones of RPE alterations (hypo- and hyperpigmentations and atrophic changes). Neither drusen nor subretinal hemorrhages were detected.
All eyes presented features consistent with chronic CSC on the fundus autofluorescence, FA, ICG angiography, and SD OCT examinations. Five eyes demonstrated granular hyperautofluorescence in the macular region, and 7 exhibited a central confluent hypoautofluorescent pattern. In 8 eyes, descendent tracts were also evident.
On fluorescein angiography, the affected zones exhibited alternating hyperfluorescent and hypofluorescent spots in the early phase; in the late phase, hyperfluorescent leaking points (in 7 eyes, 58%) or small leaking areas (5 eyes, 42%) were visible and stained the serous detachment of the retina. At the posterior pole, multiple zones of RPE alterations were also visualized in 8 of the 12 eyes.
ICG angiography revealed choroidal hyperfluorescence in all eyes that was consistent with both choroidal hyperpermeability and a subretinal neovascular network. No signs of leakage or choroidal polyps were evident on the mid- or late-stage angiograms.
The B-scan SD OCT examinations demonstrated the presence of neurosensory retinal detachments and subretinal fluid in 9 of the 12 eyes (75%) and small pigment epithelium detachments in 2 of the 12 eyes (17%). Five eyes (42%) exhibited elongation of the photoreceptor outer segment on the internal margin of the retinal detachment, and none of the 12 eyes presented with intraretinal cystic degeneration. The RPE layers exhibited distinct profiles. Specifically, a slight retinal PED with small undulations and increased reflectivity between the RPE and Bruch membrane was evident in 7 of the 12 eyes (58%), and the remaining 5 eyes (42%) presented a flat RPE profile. The mean subfoveal choroidal thickness was 400 μm (range 570–228 μm) ( Table ).
OCT angiography with the split-spectrum amplitude-decorrelation angiography algorithm revealed normal retinal circulation in all of the eyes. In 7 of the 12 eyes (58%), outer retinal OCT angiogram revealed the presence of a distinct CNV network in a pattern that was strikingly similar to that of the ICG hyperfluorescence ( Figure 1 ).
