Source Optical Coherence Tomography Angiography Research Articles

Observation of the early blood vessels of cutaneous malignant melanoma using Swept Source Optical Coherence Tomography Angiography (SS-OCTA)

Melanoma, characterized by high mortality, rapid development and accompanied with angiogenesis is the most typical malignant tumor in skin cancer. Hence, the detection of blood vessels is of much significance. The early vascular network has small scale. If we remove the tumor early and biopsy it, it will increase the spread of the cancer cells and infection and bleeding. In this case, we presented a new angiography method. A high-resolution OCT system for noninvasive angiographic imaging of early skin melanoma — Swept Source Optical Coherence Tomography Angiography (SS-OCTA) is proposed. With a high lateral resolution of 10[Formula: see text][Formula: see text]m in vivo tomographic angiography, SS-OCTA is used to image and identify the morphology of the early tumor blood vessels. In addition, a control group experiment is conducted to observe the growth of melanoma in the process of rupture, malformation of micro-vessels. The results of the analysis and statistical test ([Formula: see text]) are statistically significant.

Two-Year Risk of Exudation in Eyes with Nonexudative Age-Related Macular Degeneration and Subclinical Neovascularization Detected with Swept Source Optical Coherence Tomography Angiography

Swept source optical coherence tomography angiography (SS-OCTA) was used to study the prevalence, incidence, and natural history of subclinical macular neovascularization (MNV) in eyes with unilateral nonexudative age-related macular degeneration. Prospective cohort study. Patients were imaged using 3-× 3-mm and 6-× 6-mm SS-OCTA scan patterns. MNV was detected using the outer retina to choriocapillaris en face slab. Prevalence and incidence of subclinical MNV, Kaplan-Meier cumulative estimates for the overall risk of exudation, and the association between neovascular lesion size and the risk of exudation were assessed through 2 years. From August 2014 through March 2018, 227 patients (154 intermediate and 73 late age-related macular degeneration eyes) underwent SS-OCTA imaging. Thirty eyes (13.2%) had subclinical MNV at first imaging and 12 eyes (8.9%) developed subclinical MNV during follow-up. Of the 191 eyes with >1 visit, 19 developed exudation. Fourteen of these eyes had pre-existing subclinical MNV. The incidence of exudation from the time of first detection of any subclinical MNV was 34.5%. The relative risk of exudation after detection of subclinical MNV was 13.6 times greater (95% confidence interval 4.9-37.7) than in the absence of subclinical MNV (P < .001). There was no significant risk of exudation based on lesion size alone (P= .91). By 24months, the risk of exudation was 13.6 times greater for eyes with subclinical MNV detected by SS-OCTA compared with eyes without subclinical MNV. For eyes with subclinical MNV in the absence of symptomatic exudation, we recommend close follow-up without treatment.

Retinal and choroidal vasculature changes associated with chronic kidney disease.

Retinal and choroidal microvascular changes can be related to renal impairment in hypertension and chronic kidney disease (CKD). The study examines the association between retinochoroidal parameters and renal impairment in hypertensive, non-diabetic patients. This is a cross-sectional study on Caucasian patients with systemic arterial hypertension with different levels of renal function. All subjects were studied by blood chemistry, urine examination, microalbuminuria and blood pressure. Complete eye examination was completed with swept source optical coherence tomography (SS-OCT) and optical coherence tomography angiography (OCTA) scans of macular region. Patients were divided in groups: LowGFR and HighGFR and CKD- and CKD+, according to the value of glomerular filtrate (GFR) and albuminuria. LowGFR and CKD+ groups included patients with clinical kidney impairment. One hundred and twenty eyes of 120 hypertensive patients were evaluated. The mean retinal thickness was thinner in CKD+ versus CKD- group (p < 0.009). LowGFR and CKD+ groups showed thinner choroidal values than HighGFR (p < 0.02) and CKD- (p < 0.001) groups. OCTA showed lower density in LowGFR than in HighGFR group (p < 0.001) and in CKD+ versus CKD- group (p < 0.001). Albuminuria was inversely related to choroidal and retinal thickness measures (p < 0.001) and to the indices of superficial parafoveal (p < 0.05) and foveal (p < 0.05) vascular densities. CKD is associated with retinal thinning, eGFR and decreasing renal function with progressive reduction of choroidal and retinal vascular density. SS-OCT and OCTA documented close association between CKD and reduction of both choroidal thickness and paracentral retinal vascular density in hypertensive patients.

Influence of Axial Length on Parafoveal and Peripapillary Metrics from Swept Source Optical Coherence Tomography Angiography

ABSTRACT Purpose To assess the effect of axial length (AL) on the quantification of superficial vessel density of both macular and disc region using swept source optical coherence tomography angiography (SSOCTA). Methods This is a cross-sectional clinical study. Seventy-five eyes from 75 Chinese healthy participants (56 females) with a mean age of 26.6 ± 6.8 (range 19–50) years were included in this study. All eyes were imaged with SSOCTA, using a 3 × 3mm scan pattern centered on the macular and optic disc, respectively, and the superficial layer was used for evaluation. The image size was corrected with AL using Bennett formula. Outcome measurements included perfusion density (PD), vessel length density (VLD) in parafoveal and disc regions, averaged peripapillary large vessel diameter and area of foveal avascular zone (FAZ). Image processing and measurements was performed using Image J software. Multivariate regression analysis adjusting for age and signal strength was used to assess the influence of AL on the metrics. Results AL was the only predictive factor for parafoveal PD (β = −0.273, P = .047) and VLD (β = −0.396, P = .003). There was no correlation between AL and area of FAZ, large vessel diameter, or the vessel density on any location in disc region. Age was the only predictor for PD (β = −0.287, P = .024) and VLD (β = −0.289, P = .023) on optic nerve head. Conclusions AL was negatively correlated with superficial parafoveal microvasculature, but not correlated with peripapillary capillaries, suggesting that the inner retina stretches more in the distal end of the disc with increased AL.

Swept source optical coherence tomography angiography in patients treated with hydroxychloroquine: correlation with morphological and functional tests

PurposeTo evaluate swept source optical coherence tomography angiography (SS-OCTA) in patients treated with hydroxychloroquine (HCQ) for more than 5 years and to compare results with the tests currently recommended for...

Optical coherence tomography angiography in the diagnosis of choroidal neovascular membrane

Aim To evaluate the ability to diagnose and identify the morphologic features of choroidal neovascular membranes by optical coherence tomography angiography. Patients and methods Prospective, observational study of patients with Choroidal neovascularization (CNV) attending the outpatient clinic of Mansoura Ophthalmic Center. For all patients fluorescein angiography (FA), spectral domain optical coherence tomography (SD-OCT), and swept source optical coherence tomography angiography were done. The results were analyzed and compared. Results This study included 23 eyes of 23 patients. Seven eyes had age-related CNV and 16 eyes had myopic CNV. Activity was evident in 20 cases with dye leakage in FA and fluid accumulation in SD-OCT, while in the other three cases, no active dye leakage was present in FA in one of them with minimal fluid in structural OCT; in the other cases, structural OCT showed minimal intraretinal fluid in one case and absent intraretinal fluid in the other case. Regarding cases with evident activity in fundus fluorescein angiography (FFA) and OCT, in two cases neovascular network was evident with glomerular appearance. In 18 cases, densely interlaced network of vessels was evident. In three cases without evident activity in other imaging modalities, the membrane appeared as a tangled network with filamentous vessels and loss of small branches. Conclusion OCT angiography is a noninvasive, safe imaging tool for the diagnosis of CNV which gives information about the accurate size and localization of the membrane. It is a nonexpensive and rapid method that can be used for the diagnosis, screening of patients at risk, differentiate between active and inactive membranes, and follow-up.

Evaluation of Macular Circulation in Patient with Sudden Visual Loss Secondary to Behcet's Perifoveal Vasculitis by using (Retinal Flow) Swept-Source Optical Coherence Tomography Angiography Map

Objective: To evaluate macular vascular circulation in patient with perifoveal vasculitis secondary to Behcet’sdisease by using (Retinal Flow) swept source optical coherence tomography angiography map.Case report: We retrospectively review a 39-year-old female patient, with history of Behcet’s disease, presented with history of sudden unexplained central loss of vision which was more significant on the right eye with best corrected vision (BCVA=0.1) and less on the left eye with best corrected visual acuity (BCVA=0.7). The clinical ophthalmic examination of both anterior and posterior segments for the both eyes were normal with no any signs of uveitis. Imaging with DRI Triton Swept Source (SS- OCTA) (Topcon, Japan) was performed for evaluation of both superficial and deep capillary plexus of macular area. Fluorescein angiography (FA) was used also for assessing foveal avascular zone features.Results: The SS-OCTA Retinal Flow map was more sensitive than FA in marking out hypoperfusion in both superficial capillary plexus (SCP), and deep capillary plexus (DCP), especially in the right eye which had the positive correlation with visual acuity. SS-OCTA Retinal Flow map was also sensitive in showing improvement of macular hypoperfusion after treatment of Behcet’s Perifoveal Vasculitis.Conclusion: OCTA is a noninvasive imaging modality that can be used to evaluate macular vascular changes in Bechet’s perifoveal vasculitis and can explain acute visual loss in Behcet.

Improving visualization and quantitative assessment of choriocapillaris with swept source OCTA through registration and averaging applicable to clinical systems

Choriocapillaris (CC) visualization and quantification remains challenging. We propose an innovative three-step registration and averaging approach using repeated swept source optical coherence tomography angiography (SS-OCTA) scans to conduct automatic quantitative assessment on CC. Six subjects were enrolled, each imaged at several locations with SS-OCTA from macular to equatorial regions using 3 mm × 3 mm scanning pattern. Five repeated volumes were collected for each subject. The complex optical microangiography (OMAG) algorithm was applied to identify blood flow in CC slab. An automatic three-step registration of translation, affine and B-Spline was applied to en face OCTA images of CC, followed with averaging. A fuzzy clustering approach was used to segment vasculature and flow deficits from the averaged images. The improvement in visualization of CC was evaluated and the average intercapillary distance was estimated by calculating the averaged capillary lumen spacing. A series of quantitative indices of flow deficit density, number, size, complexity index and aspect ratio index (FDD, FDN, FDS, FDCI and FDARI) were designed and validated with the increase of repeated scan numbers for averaging. Quantitative assessment was applied and compared on CC in macular and equatorial regions. The intercapillary distance was observed to be around 24 µm at macula and increased toward equatorial regions. All five quantitative indices (FDD, FDN, FDS, FDCI and FDARI) showed significant changes with multiple averaging and tend to become stable with repeated number of 4. Our proposed registration and averaging algorithm significantly improved the visualization of CC with SS-OCTA. The designed five indices for CC provide more options in the quantitative assessment of CC and are of great potentials in assisting the understanding of disease pathology, early diagnosis and treatment monitoring.

Variation of Retinal and Choroidal Vasculatures in Patients With Age-Related Macular Degeneration

To investigate variations in chorioretinal vasculatures in fellow eyes of patients with unilateral neovascular age-related macular degeneration (nAMD). We included fellow eyes of consecutive patients with unilateral nAMD from swept source optical coherence tomography (SS-OCT) angiography database. Vascular and nonvascular indices were determined based on SS-OCT and SS-OCT angiography images. Variation of the vascular or nonvascular index was compared between fellow eyes with and without early AMD. In 146 fellow eyes, 88 (60.3%) had early AMD and 58 (39.7%) had a normal fundus. Vascular density (VD) values of the superficial and deep retinal capillary plexus and choriocapillaris were smaller in eyes with early AMD than in those without (P < 0.001, P = 0.001, P = 0.006, respectively). Flow void area in choriocapillaris was greater in eyes with early AMD than those without (P = 0.015). In 88 fellow eyes with early AMD, vascular indices of the retina were correlated with those of choroid while nonvascular indices were not. Fellow eyes of patients with classic exudative AMD had greater foveal avascular zone area and smaller VD values of the deep retinal capillary plexus than those with polypoidal choroidal vasculopathy (P < 0.001, P = 0.004). In addition to vascular insufficiency in the choroid or choriocapillaris, retinal vascular alteration was apparent in eyes with early AMD. It may suggest that retinal vessels were involved in the pathogenesis of AMD even while changes in nonvascular components of the retina were not yet apparent.

Quantitative changes in the ageing choriocapillaris as measured by swept source optical coherence tomography angiography

AimTo analyse quantitative optical coherence tomography angiography (OCTA) parameters of choriocapillaris (CC) at the foveal, perifoveal and parafoveal regions in healthy subjects of different age.MethodsIn this observational cross-sectional study, consecutive...

Visualizing large choroidal blood flow by subtraction of the choriocapillaris projection artifacts in swept source optical coherence tomography angiography in normal eyes

Optical coherence tomography angiography (OCTA) seems not to image the choroidal blood flow pattern in the normal individual because of the OCT light attenuation. Our purpose in the current study was to visualize the large choroidal blood flow pattern after subtraction of the choriocapillaris projection artifact in normal eyes non-invasively by swept source (SS) OCTA. Sixty-one eyes of 45 individuals (19 men, 26 women) without ocular disease were examined by SS-OCTA (AngioPlex Elite 9000, Zeiss, Germany). A 12 × 12 mm macular area was scanned. Subfoveal choroidal thickness (SCT) was measured, and the choroidal blood flow pattern in a slab of 30 µm width at one-half of SCT was analyzed. In examining the choroidal blood flow pattern, a slab that was between 30 to 60 µm posterior to the retinal pigment epithelium, in which the choriocapillaris blood flow was most clearly imaged, was used for the subtraction of the projection artifacts from the choriocapillaris on the stromal area of choroid. The ratio (%) of the choroidal blood flow area in the whole choroidal region was calculated after binarization. Thirty-four eyes of 27 individuals (12 men, 15 women) were also examined by spectral domain OCTA (SD-OCTA). After the subtraction, the middle and large choroidal blood flow were clearly visible in SS-OCTA in all eyes. The mean SCT was 297 ± 61 µm, and the mean ratio of the choroidal blood flow area was 27.3 ± 8.2%, which was significantly correlated with SCT (R = 0.738, P < 0.01). SD-OCTA did not show the choroidal blood flow pattern. In conclusion, removal of the projection artifacts of choriocapillaris can make the choroidal blood flow visible in SS-OCTA of normal eyes. Because the ratio of choroidal blood flow area was correlated with SCT, the choroidal blood flow might be an important factor related to the choroidal thickness.

Swept source optical coherence tomography and optical coherence tomography angiography in pediatric enhanced S-cone syndrome: a case report

BackgroundEnhanced S-cone syndrome is an autosomal recessive retinal dystrophy related to a defect in a nuclear receptor gene (NR2E3) that leads to alteration in cells development from rod to S-cone. This retinal dystrophy may be associated with retinal schisis. The aim of this report is to describe structural optical coherence tomography and optical coherence tomography angiography features in a case of enhanced S-cone syndrome associated with macular schisis.Case presentationA Caucasian 13-year-old girl underwent measurement of best corrected visual acuity, ophthalmoscopic evaluation, and fundus autofluorescence examination. Photopic and scotopic electroretinography were carried out as well. Enhanced S-cone syndrome was suspected on the basis of clinical and electrophysiological findings. Structural optical coherence tomography and optical coherence tomography angiography allowed the further characterization of the associated macular schisis.Genetic analysis not only confirmed the diagnosis but increased the clinical novelty of this case report by showing two variations in the NR2E3 gene probably related to the phenotype: a missense variation c.1118T>C which leads to the substitution of leucine with proline in amino acid position 373, and c.349+5G>C, which involves a gene sequence near a splicing site.ConclusionsSwept source structural optical coherence tomography (B scans and “en face” images) and optical coherence tomography angiography allowed the observation of retinal structural details and the involvement of each retinal layer and capillary plexus in enhanced S-cone syndrome. Of interest, neither of the two NR2E3 gene variants found in this case report have been linked to any form of retinopathy.

Bimodal imaging of proliferative diabetic retinopathy vascular features using swept source optical coherence tomography angiography

To categorize neovessels morphology and to detect response to anti-angiogenic therapy by using structural and angiographic modes of swept source optical coherence tomography (SS-OCT). Thirty-two eyes with neovessels at disc (NVD) and neovessels elsewhere (NVE) - as diagnosed by fluorescein angiography- were included. Cross sectional OCT images of disc and macular regions were registered to enface OCT angiography (OCTA), B-scan blood flow over lay and density maps. Three eyes received anti-angiogenic treatment. Pin point registration of cross-sectional OCT and OCTA images differentiated active NVD with vascular elements from fibrous or equivalent fibrovascular elements. En face images delineated NVE as vascular tufts or area of filling while cross-sectional images differentiated NVE from microvascular intraretinal abnormality (IRMA). All cases were associated with enlargement of foveal avascular zone and or areas of capillary non perfusion. Regressed NVD appeared as ghost vessel or pruned vascular loops after injection. Structural and angiographic modes of SS-OCT can detect, characterize and categorize the pattern of wide spectrum of neovessels based on blood flow data and density maps. It is potentially useful to detect ischemic changes in the vascular bed and regression of NVD after therapeutic regimens providing substitute for invasive techniques.

Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

BackgroundThere are two forms of system implementation of optical coherence tomography angiography (OCTA) in ophthalmic imaging, i.e., spectral domain (SD-) and swept source OCTA (SS-OCTA). The purpose of this paper is to compare the SD-OCTA and SS-OCTA for elucidating structural and vascular features associated with central serous retinopathy (CSR), and to evaluate the effects of CSR on SD- and SS-OCTA’s imaging capabilities.MethodsNormal subjects and CSR patients were imaged by SD- and SS-OCTA using 3 × 3 mm and 6 × 6 mm scan patterns. OCT signal strengths at the superficial retina, deep retina, Sattler’s layer and Haller’s layer were used to compare the ability of SD- and SS-OCTA to image structural features. In addition, the ability to acquire angiograms were discussed by evaluating retinal vessel density. Central serous volume (CSV) was measured and it was correlated with difference in signal strengths (∆S) between two OCTA devices.ResultsSeven normal eyes and seven diseased eyes were recruited. Results showed no significant differences between SD- and SS-OCT in detecting structural features of the retinal layer according to the paired t-test. However, when imaging the Sattler’s layer for normal eyes, a significant difference is found between SD- and SS-OCT (p < 0.0001 for 3 × 3 mm scan, and p = 0.0002 for 6 × 6 mm); while for CSR eyes, the corresponding values were p < 0.0001 and p = 0.0003, respectively. At Haller’s layer for normal eyes, the corresponding values were p = 0.0004 and p = 0.0014; and for CSR eyes, p = 0.0004 and p < 0.0001, respectively. A strong correlation between ∆S and CSV was observed in the Sattler’s layer (3 × 3 mm – p = 0.0031 and R2 = 0.951; 6 × 6 mm – p = 0.0075 and R2 = 0.911) and Haller’s layer (3 × 3 mm – p = 0.0026 and R2 = 0.955; 6 × 6 mm – p = 0.0013 and R2 = 0.972).ConclusionsThe results suggest no differences between SD- and SS-OCTA for imaging the retinal layers however, when imaging beyond retinal layers, SS-OCTA appears advantageous in detecting returning signals. In CSR cases, the CSV may have an impact on sub-CSR tissue imaging and appears to have more impact on SD- than SS-OCTA.

Accurate estimation of choriocapillaris flow deficits beyond normal intercapillary spacing with swept source OCT angiography.

To estimate choriocapillaris flow deficits beyond normal intercapillary distance with swept source optical coherence tomography angiography (SS-OCTA). Subjects were enrolled and repeated SS-OCTA scans were performed using the 3 mm × 3 mm scan pattern. Blood flow was identified using the complex optical microangiography (OMAGc) algorithm. The choriocapillaris (CC) was defined as a 20 µm slab of the flow volume beneath the outer boundary of Bruch's membrane (BM) and was compensated with the corresponding structural image for flow deficits measurement. Flow deficits were segmented based on one mean standard deviation from a normal database. A histogram based thresholding method was developed to remove small flow deficits that were determined by examining intercapillary spacing within normal CC networks. A registration method based on affine and B-spline transformation was utilized for the CC angiogram averaging. Four repeated scans were averaged, and results were compared with and without removal of small flow deficits after averaging a different number of scans (N=1, group 1; N=2, group 2; N=3, group 3 and N=4, group 4). Seven normal subjects were enrolled. Intercapillary distance was found to be 24 µm for the CC networks under OCTA, which was used as the threshold to exclude small flow deficits for CC quantification. After averaging, significant reduction in background noise and improvement in continuity of blood vessel networks were observed both on retinal and choriocapillaris angiograms. Flow deficit percentages of the choriocapillaris were significantly reduced with averaging (group 1 vs. group 2: P<0.0001; group 2 vs. group 3: P<0.001; group 3 vs. group 4: P<0.001). The flow deficit percentages were also significantly reduced after removing the small flow deficits (≤24 µm in diameter) in all groups (P<0.01). A statistically significant difference was found after removing small flow deficits (≤24 µm in diameter) between group 1 and group 2 (P<0.001), between group 2 and group 3 (P<0.05), and between group 3 and group 4 (P<0.05). However, the significance was decreased compared to that without small flow deficits removal. A method was developed to improve the robust estimation of choriocapillaris flow deficits by removing the small flow deficits corresponding to normal intercapillary spacing. After the removal of small flow deficits, fewer repeats were required for image averaging to achieve comparable accuracy of flow deficit measurements with SS-OCTA.

Imaging the Deep Choroidal Vasculature Using Spectral Domain and Swept Source Optical Coherence Tomography Angiography

To evaluate the deeper choroidal vasculature in eyes with various ocular disorders using spectral domain (SD) optical coherence tomography angiography (OCTA) and swept source (SS) OCTA. Patients underwent OCTA imaging with either SD-OCTA (Zeiss Cirrus Angioplex or Optovue AngioVue) or SS-OCTA (Topcon Triton). Retinal pigment epithelium (RPE) integrity, structural visualization of deep choroidal vessels on en face imaging, and OCTA of deep choroidal blood flow signal were analyzed. Choroidal blood flow was deemed present if deeper choroidal vessels appeared bright after appropriate segmentation. Structural visualization of choroidal vessels was feasible in all eyes by en face imaging. In both SD-OCTA and SS-OCTA, choroidal blood flow signal was present in all eyes with overlying RPE atrophy (100% of eyes with RPE atrophy, 28.6% of all imaged eyes, P < .001). While choroidal vessels can be visualized anatomically in all eyes by en face imaging, choroidal blood flow detection in deep choroidal vessel is largely restricted to areas with overlying RPE atrophy. Intact RPE acts as a barrier for reliable detection of choroidal flow using current OCTA technology, inhibiting evaluation of flow in deeper choroidal vessels in most eyes.

Aflibercept Treatment Leads to Vascular Abnormalization of the Choroidal Neovascularization.

Recent studies do not support the hypothesis of vascular normalization in the eyes receiving various types of intravitreous antivascular endothelial growth factor (VEGF). This retrospective study considered 57 eyes of 32 patients with vascular age-related macular degeneration (AMD) undergoing aflibercept treatment. In this study, we measured the vessel density, Horton-Strahler (HS) ramification ratio (complexity), and the length ratio in 14 eyes with choroidal neovascularization treated with 3–5 Eylea injections, 17 eyes receiving 1-2 injections, and 14 treatment-naïve eyes to the use of swept source optical coherence tomography angiography (OCTA). Macular 6 × 6 mm scans were acquired using the DRI OCT Triton by a single trained technician. OCTA images were standardized, binarized, and skeletonized using ImageJ. Then, the HS analysis of the CNV was performed. Our data suggest that the vascular density significantly decreases after an anti-VEGF injection 36 and 93 versus 41 and 87 in treatment-naïve patients. Moreover, CNV before the treatment and in a group with 3–5 injections was more complex than after receiving 1-2 injections. The branch length was not changed. Repeated anti-VEGF can lead to vascular abnormalization and further research is needed to confirm the results of this study.

Compact akinetic swept source optical coherence tomography angiography at 1060 nm supporting a wide field of view and adaptive optics imaging modes of the posterior eye.

Imaging of the human retina with high resolution is an essential step towards improved diagnosis and treatment control. In this paper, we introduce a compact, clinically user-friendly instrument based on swept source optical coherence tomography (SS-OCT). A key feature of the system is the realization of two different operation modes. The first operation mode is similar to conventional OCT imaging and provides large field of view (FoV) images (up to 45° × 30°) of the human retina and choroid with standard resolution. The second operation mode enables it to optically zoom into regions of interest with high transverse resolution using adaptive optics (AO). The FoV of this second operation mode (AO-OCT mode) is 3.0° × 2.8° and enables the visualization of individual retinal cells such as cone photoreceptors or choriocapillaris. The OCT engine is based on an akinetic swept source at 1060 nm and provides an A-scan rate of 200 kHz. Structural as well as angiographic information can be retrieved from the retina and choroid in both operational modes. The capabilities of the prototype are demonstrated in healthy and diseased eyes.

Features of choroidal naevi on swept source optical coherence tomography angiography and structural reverse flow optical coherence tomography

The purpose of our study was to describe features of choroidal naevi as seen on swept source optical coherence tomography angiography (OCTA) and also on en face images derived from structural data from OCTA. A prospective observational cohort study was carried out. Patients attending a specialised choroidal naevomelanocytic with known naevi were imaged with swept source OCTA. Seventy-one eyes of 70 patients were imaged. Forty-three patients and 44 eyes were included. Mean age was 57.7years (SD 14.9), range 29-81years. Male to female ratio was 20:23. On OCTA after manual segmentation, naevi could be seen in 47.6% of cases, whereas in the en face images, naevi could be clearly visualised in 79.5% of cases. In OCTA, the superficial and deep capillary plexuses appeared undisturbed as did the outer retinal layer appeared in all cases of flat naevi. In choroidal naevi with mild elevation, the outer retinal layer appeared more susceptible to projection artefacts from overlying retinal vasculature. The choriocapillaris layer showed a fading of the normal homogenous vascular mosaic corresponding to the area of the naevus. In the en face images, even the faintest and thinnest naevi could be visualised in striking detail, and naevi greater than 120μm thickness appeared darker (p = 0.0034). OCTA presents characteristic changes in the choriocapillaris layers in cases of choroidal naevi. The association of naevus substance appearing darker with increasing thickness may offer a novel prognostic clue. En face structural OCT may allow accurate, detailed measurement of lateral dimensions which could be of value in the monitoring of suspicious naevi.

Observation of neovascularization of the disc associated with proliferative diabetic retinopathy using OCT angiography.

To describe the relationship between the vitreous and the neovascularization of the disc (NVD) using swept source optical coherence tomography (SS-OCT) and OCT angiography (OCTA). Retrospective. We examined 17 eyes of 11 consecutive patients diagnosed as NVD associated with proliferative diabetic retinopathy (PDR). The location of the NVD feeder or collector vessels were examined by using RTVue XR Avanti. To determine the condition of the posterior vitreous detachment (PVD) and the proliferative tissue of the NVD, we performed 12 mm horizontal and vertical scans through the disc using SS-OCT. OCT images of all 17 cases indicated there was no PVD on the optic disc. OCTA showed that the locations of the newly formed vessels from the optic disc were overwhelmingly outside the physiological cupping (95%). No cases exhibited formation of neovascularization inside the physiological cupping. OCT images revealed all 17 eyes had proliferative tissues located under the posterior wall of the vitreous, with 12 out of 17 eyes exhibiting additional invasion of the proliferative tissue into the vitreous through the posterior wall. Epiretinal membrane or a thickened posterior wall of the vitreous was present in 10 out of the 17 eyes. NVD associated with PDR arises from outside the physiological cupping and grows along the posterior wall of the vitreous. The absence of PVD on the optic disc is essential to the growth of NVD.