Choriocapillaris Flow Voids Research Articles

Decreased choriocapillaris vessel density in the ipsilateral eye after carotid artery revascularization detected by widefield SS-OCTA.

ObjectiveTo investigate the short-term blood flow changes and image features of the retina and choroid in patients undergo carotid artery revascularization (CAR) for severe carotid artery stenosis (SCAS) using widefield swept-source optical coherence tomography angiography (SS-OCTA). DesignProspective study. ParticipantsThis prospective study included 112 eyes (56 eyes of the ipsilateral side and 56 eyes of the contralateral side) of 56 participants with severe carotid artery stenosis. MethodsParticipants were examined using widefield SS-OCTA covering an area of 16*16mm centered on the fovea before and after carotid artery revascularization. Retinal parameters including central macular thickness (CMT), vessel density of the retinal superficial vascular complex (VDRSVC), vessel density of the retinal deep vascular complex (VDRDVC), and vessel density of the retina (VDR) and choroidal parameters including central choroidal thickness (CCT), vessel density of the choriocapillaris (VDCC), vessel density of the medium and large choroidal vessels (VDMLC), choroidal vessel volume ratio (CVV/a), and three-dimensional choroidal vascularity index (3D-CVI) were measured. Besides, preoperative and postoperative OCTA images were screened and compared. Main Outcome MeasuresRetinal and choroidal parameters obtained from SS-OCTA. ResultsIn the ipsilateral eye (56 eyes), increase of VDRSVC, VDR, CVV/a, CCT, and 3D-CVI and decrease of VDCC was found after CAR. 13 patients were identified with postoperative ipsilateral choriocapillaris flow voids (PICCFVs) with OCTA images, and presence of PICCFVs was associated with greater postoperative VDCC decrease. In the contralateral eye (56 eyes), we found increase of VDRSVC, VDRDVC, VDR, while no difference of choroidal parameters after CAR and no findings of PICCFVs. ConclusionsFindings of this study suggest that ocular microvascular perfusion is improved after CAR in the ipsilateral eye and the contralateral eye within a wide field of the fundus. The VDCC is decreased in the ipsilateral eye, which may indicate infarctions of choriocapillaris or ischemia-reperfusion injury of the choriocapillaris after CAR.

Choroidal and Choriocapillaris Changes after Photodynamic Therapy and Subthreshold Micropulse Laser Treatment for Central Serous Chorioretinopathy

Background and Objectives: The aim of the present study is to analyze choroidal and choriocapillaris structural and functional changes in eyes affected by Central serous chorioretinopathy after Photodynamic Therapy (PDT) and Subthreshold Micropulse laser (SML) treatment. Materials and Methods: Forty-two eyes of forty-two patients were analyzed in this observational study. Twenty-four patients underwent SML treatment, whereas eighteen patients were treated with PDT. Examinations were performed at baseline and after 3 months of treatment. Main outcome measures were: Best corrected visual acuity (BCVA), central macular thickness (CMT), central choroidal thickness (CCT), pigment epithelial detachment (PED) presence and maximum height (PEDMH), and choroidal vascularity index (CVI) measured by means of Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) Optical coherence tomography (OCT) and choriocapillaris flow voids (CCFV) measured on Optical Coherence Tomography Angiography (OCT-A) platform PLEX Elite 9000 device (Carl Zeiss Meditec Inc., Dublin, CA, USA). Results: Changes in BCVA were registered in both groups over time (p < 0.001). Structural changes in terms of reduced CMT and PED presence were noted in the two groups at follow-up (p < 0.001 and p = 0.001, respectively). Structural and functional choroidal changes were found in the two groups with reduced CCT and CVI over time (p = 0.004 and p = 0.007, respectively), with significant differences between the two groups for CVI parameter (p = 0.001). CCFV increased over time in the PDT group and decreased in the SML group. Conclusions: PDT and SML are effective approaches in CSC eyes and are able to improve structural and functional parameters over time. Choroidal and choriocapillaris parameters are promising biomarkers able to monitor disease course, showing greater impact of PDT on choroid-choriocapillaris complex over time.

The effect of heart rate variability on the choroidal vascularity of the optical coherence tomography and angiography in central serous chorioretinopathy.

To investigate the correlation between the autonomic nervous system and choroidal vascularity in patients with central serous chorioretinopathy (CSC), using heart rate variability (HRV) analysis, optical coherence tomography (OCT) and OCT angiography (OCTA). We retrospectively analyzed data of 25 patients with unilateral CSC (50 eyes, including the unaffected fellow eyes) and 25 healthy controls. The assessment involved a 5-minute HRV analysis encompassing both frequency and time domains, especially low frequency (LF), high frequency (HF), and LF/HF ratio. In OCT (12 × 9mm) and en-face OCTA (3 × 3mm) scans, we measured parameters including choroidal vascularity index (CVI), choroidal vessel density in the middle and deep layers, and choriocapillaris flow void. Regression analysis was conducted to elucidate the associations between HRV parameters and OCT/OCTA measurements. Normalized LF(LFnorm) and LF/HF ratios were higher in patients with CSC than in healthy controls. LFnorm and the log-transformed ratio of LF to HF [log(LF/HF)] demonstrated a significant and borderline correlation with CVI in the linear regression analysis (P = 0.040, R2 = 0.171, and P = 0.059, R2 = 0.147, respectively). Both CVI and deep choroid vessel density showed a more significant association with LFnorm and log (LF/HF) in the non-linear quadratic regression analysis than in the linear analysis (all, P < 0.04, R2 > 0.25). The frequency-domain parameters of HRV, including LFnorm and log (LF/HF), demonstrated a significant association with indicators reflective of large choroidal vessel luminal area on macular OCT/OCTA scans. This observation implies complicated modulation of choroidal blood flow by the autonomic nervous system in CSC.

Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

To evaluate best-corrected visual acuity (BCVA), retina sensitivity (RS), and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of retinal inner and outer layers (DRIL/DROL) and ischemia in OCT/OCT angiography (OCTA) in diabetic retinopathy (DR). Retrospective case-control study. Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, and active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls. A detailed grading of MP and OCT/OCTA images using Image J software, and specific Image Manipulation Program was applied to colocalize the presence of retina disorganization and RS. Best-corrected visual acuity and RS were correlated with the disorganization of retina layers' characteristics and grading (grade 1-DRIL; grade 2-DROL; grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of colocalization was applied to the vascular layers on OCTA using MATLAB. Correlation between BCVA and MP parameters with disorganization of retina layers grading and OCTA parameters. Best-corrected visual acuity, mean RS within 1 mm and central 3 mm (overall RS [oRS]), perfusion density, vessel density, and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (P < 0.001). Mean RS within 1 mm (21.4 decibels [dB] ± 2.4 vs. 13.8 dB ± 5.4, P= 0.002), oRS (22.0 dB ± 2.1 vs. 14.4 dB ± 4.6, P < 0.001), and BCVA (76.1 ± 7.4 vs. 61.2 ± 20.4 ETDRS letters; P= 0.02), had a significant decrease from grade 1 to grade 3 retina disorganization. Choriocapillaris flow voids (CC-FVs) increased from grade 1 to grade 3 (DROL plus) (P= 0.004). Overall retina sensitivity and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2= 0.45. Cases had more dense scotomas (P= 0.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL (P= 0.04). Microperimetry and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Unveiling the Hidden: Early Manifestations of Extensive Macular Atrophy with Pseudodrusen-like appearance.

To describe novel microperimetry and imaging findings in two patients affected by extensive macular atrophy with pseudodrusen-like appearance (EMAP) without signs of retinal pigment epithelium (RPE) atrophy. Case series. Both patients underwent mesopic and dark-adapted two-color scotopic microperimetry, followed by multimodal imaging assessment including ultra-widefield photography, fundus autofluorescence (AF), high-resolution optical coherence tomography (Hi-Res OCT), OCT angiography and high-magnification module (HMM). Albeit normal visual acuity, both patients had a significant reduction of retinal sensitivity - especially under scotopic cyan conditions. One patient had macular pigment abnormalities, while the combination of blue and near-infrared AF modalities highlighted different patterns of pseudodrusen-like lesions.Of notice, Hi-Res OCT revealed a marked separation between the RPE and Bruch's membrane, containing a hyperreflective material with two different reflectivities. OCT angiography excluded the presence of macular neovascularization and documented several choriocapillaris flow voids. HMM images showed severe alteration of photoreceptors' mosaic in the perifovea. Our comprehensive assessment of two stage 1 EMAP patients revealed a predominant damage of perifoveal rods over areas of RPE-Bruch's membrane separation. These findings underscore the importance of basal laminar deposits in the initial stages of EMAP, contributing to a deeper understanding of its underlying mechanisms.

Choroidal features in non-neovascular and neovascular pachychoroid diseases.

To evaluate choroidal findings on multimodal imaging in eyes within pachychoroid spectrum diseases and to compare quantitative and qualitative choroidal features between non-neovascular (NNV-PDS) and neovascular (NV-PDS) pachychoroid diseases. Retrospective cross-sectional study comparing between NV-PDS and NNV-PDS. All patients underwent multimodal imaging including infracyanine green angiography (IFCGA) and swept source optical coherence tomography (OCT) and angiography (OCT-A). The following parameters were analyzed: subfoveal choroidal thickness (SFCT), choroidal vascular index (CVI), presence of pachyvessels and choroidal vascular interconnections (CVIC), presence of choroidal neovascularization and choriocapillaris density. Of the 87 eyes included in the study, 63 eyes (73%) had NNV-PDS and 24 eyes (27%) had NV-PDS. Mean SFCT and CVI were significantly higher in NNV-PDS group (p = 0.01; p = 0.022). Pachyvessels were more diffusely distributed in NNV-PD group and more focally distributed in NV-PDS group (p = 0.029). CVIC were more frequently noted in NV-PDS group (p = 0.024). A higher CVI was associated to a thicker choroid (p < 0.001), with significant negative correlations between the presence of CVIC and both SFCT (p = 0.015) and CVI (p = 0.002). We also observed a lower choriocapillaris vascular density and higher number of choriocapillaris flow voids in eyes with NNV-PDS (p = 0.24; p = 0.61). NNV-PDS eyes had a significantly thicker SFCT, higher CVI and a lower rate of detected CVIC than eyes with NV-PDS. These highlighted choroidal vascular changes might lead to a better understanding of pachychoroid disease pathophysiology. More frequently observed in NV-PDS group, CVIC are believed to assess the development of vortex vein anastomoses as a remodelling process for vascular decongestion.

Modifications in ocular microperfusion after transcatheter aortic valve implantation

Cerebral embolization is a known complication of transcatheter aortic valve implantation (TAVI) but the effect of the procedure on the ocular perfusion is currently unclear. Thus, we investigated post-procedural morphologic and perfusion changes of the retina and choroid, using optical coherence tomography angiography (OCTA) and color fundus photography (CFP) in a prospective cohort study. Ophthalmic examinations were conducted pre- and post-TAVI. OCTA images were analyzed quantitatively based on vessel density and skeleton density of the superficial and deep retinal plexus as well as the signal intensity and flow deficits in the choriocapillaris. CFP images were assessed for presence of acute retinal ischemia, optic nerve swelling, vessel emboli, hemorrhages and cotton wool spots. Data was analyzed using linear mixed models. Twenty patients (9 women; 11 men) at a mean age of 81 ± 6 years were included. Pre- and post-interventional ocular imaging data were available for 32 eyes. The analysis revealed a significant impairment of the choriocapillaris perfusion after TAVI with an increased proportion of flow deficits (p = 0.044). When controlling for blood pressure, the average size of choriocapillaris flow voids was significantly increased (systolic and diastolic, p = 0.039 and 0.029). Qualitatively, focal areas of retinal ischemia were detected on OCTA in 33% of participants. Silent emboli or cotton wool spots were identified on CFP in 21%. Our findings indicate a reduced choroidal perfusion as well as areas of retinal ischemia and embolization in a considerable proportion of patients following TAVI. Pending confirmation in a larger sample, these complications merit monitoring as well as inclusion in consent procedures for TAVI.

Recent Advances in Imaging Polypoidal Choroidal Vasculopathy with Swept-Source Optical Coherence Tomography Angiography.

The gold standard for polypoidal choroidal vasculopathy (PCV) diagnosis is indocyanine green angiography (ICGA), but optical coherence tomography angiography (OCTA) has shown promise for PCV imaging in recent years. However, earlier generations of OCTA technology lacked the diagnostic efficacy to replace ICGA. Swept-source optical coherence tomography angiography (SS-OCTA), the latest generation of OCTA technology, has significantly improved penetrating ability, scanning speed, scanning range, and overall image quality compared with earlier generations of OCTA. SS-OCTA reveals a "tangled vasculature" pattern of polypoidal lesions (PLs), providing evidence that they are neovascular rather than aneurysmal structures. New choroidal biomarkers, such as the choriocapillaris flow void (FV), have been identified to explain the development of PCV lesions. Although no direct comparison between SS-OCTA and previous OCTA generations in terms of diagnostic capability has been performed, SS-OCTA has shown several advantages in differential diagnosis and monitoring early reactivation for PCV. These improvements make SS-OCTA a valuable tool for PCV diagnosis and follow-up, and it may become more important for this disease in the future. This review summarized recent advances in PCV morphology and structure, as well as the possible pathogenesis based on SS-OCTA findings. The value of SS-OCTA for PCV management is discussed, along with remaining issues, to provide an updated understanding of PCV and OCTA-guided management.

Effect of red-light therapy on retinal and choroidal blood perfusion in myopic children.

To investigate the effect of repeated low-level red-light therapy (RLRLT) on retinal and choroidal blood perfusion in myopic children. Forty-seven myopic children (mean spherical equivalent refractive error [SE]: -2.31 ± 1.26 D; age range: 8.0-11.0 years) were enrolled and received RLRLT (power 2 mW, wavelength 650 nm) for 3 min twice a day, while 20 myopic children (SE: -2.75 ± 0.84 D; age range: 7.0-10.0 years) were included as a control group. All participants wore single-vision distance glasses. Refractive error, axial length (AL) and other biometric parameters were measured at baseline and during follow-up visits in the first, second and fourth weeks after initiation of treatment. Retinal thickness, subfoveal choroidal thickness (SFCT), total choroidal area (TCA), luminal area (LA), stromal area (SA) and choroidal vascularity index (CVI) were obtained using optical coherence tomography (OCT). The percentage retinal vascular density (VD%) and choriocapillaris flow voids (FV%) were measured using en-face OCT angiography. After 4 weeks of treatment, a significant increase in SFCT was observed in the RLRLT group, with an average increase of 14.5 μm (95% confidence interval [CI]: 9.6-19.5 μm), compared with a decrease of -1.7 μm (95% CI: -9.1 to 5.7 μm) in the control group (p < 0.0001). However, no significant changes in retinal thickness or VD% were observed in either group (all p > 0.05). In the OCT images from the RLRLT group, no abnormal retinal morphology related to photodamage was observed. Thehorizontal scans revealed an increase in TCA, LA and CVI over time (all p < 0.05), while SA and FV% remained unchanged (both p > 0.05). These findings indicate that RLRLT can enhance choroidal blood perfusion in myopic children, demonstrating a cumulative effect over time.

Influence of a long-distance optical imaging workbench on accommodation and choroidal response in myopic children

ABSTRACT Clinical relevance Optical approaches to modulating near work may be beneficial in arresting the progression of myopia Background To explore whether a long-distance optical image workbench (LOIW) can replace traditional near-distance reading and has beneficial influences on accommodation and choroidal parameters. Methods This self-control study included two sessions. In session 1, an open-field autorefractor measured sustained accommodative response and pupil diameter when participants viewed virtual images from 3.42 m away through LOIW with + 0.50 D over-correction lenses (3.42 m/+0.50 D), LOIW with full-correction lenses (3.42 m/FC), or the visual target at a given distance of 0.33 m with + 0.50 D over-correction lenses (0.33 m/+0.50 D), with full-correction lenses (0.33 m/FC). In session 2, swept-source optical coherence tomography angiography assessed subfoveal choroidal thickness (SFChT), choroidal volume (CV), and choriocapillaris flow void percentage (FV%) at baseline and before and after reading via LOIW with + 0.50 D over-correction lenses (Far/+0.50 D) or in habitual near distance with full-correction (Near/FC) for a sustained 30-min period. Results Thirty-five myopic (mean spherical equivalent refraction: −1.11 ± 0.78 D) children (median [range] age: 8.36 [8–10] years) were analysed. Children viewing virtual images in 3.42 m/+0.50 D exhibited mild-degree accommodative leads (−0.54 ± 0.17 D), much smaller pupil diameter (3.39 ± 0.63 mm) and microfluctuations (0.13 ± 0.04 D); accommodative lags (0.88 ± 0.04 D), larger pupil diameter (5.05 ± 0.75 mm) and microfluctuations (0.88 ± 0.16 D) were observed in 0.33 m/+0.50 D, and the microfluctuations were unstable (F = 2.185, p = 0.038). Compared with baseline data, SFChT, CV, and FV% changed by 13.40 ± 4.71 μm, 0.26 ± 0.21 mm3, and − 0.14%±3.66% in Far/+0.50 D, respectively, while changes under Near/FC were − 10.19 ± 7.48 μm, −0.15 ± 0.22 mm3 and 1.95%±2.92%, respectively. All changes differed significantly between these two conditions (all p < 0.001). Conclusion The long-distance working mode may exert beneficial effects on accommodative and choroidal parameters in myopic children compared with traditional near work.

In Vivo Visualization and Quantification of Optic Disc Microvasculature for Assessing Renal Dysfunction

To assess the relationship between optic disc microvasculature and renal function in subjects with diabetes mellitus without diabetic retinopathy (DR). Prospective, cross-sectional study. A total 1629 patients with type 2 diabetes mellitus without DR were recruited from the community of Guangzhou, China. All subjects underwent 6 mm× 6 mm OCT angiography (OCTA) centered on the optic nerve head. Four state-of-the-art microcirculation parameters, including peripapillary vessel density (PVD) in the radial peripapillary capillaries (RPC), superficial capillary plexus, deep capillary plexus (DCP), and a choriocapillaris flow void density percentage (CC FVD%) were assessed via swept-source OCTA. Renal function was assessed by levels of microalbuminuria (MAU) and estimated glomerular filtration rate (eGFR). Compared with non-chronic kidney disease (CKD) participants, PVD was significantly lower in subjects in the CKD group and worsened as eGFR declined. After adjustment for covariates, higher eGFR was significantly associated with higher PVD in the RPC (β= 0.01; 95% confidence interval [CI], 0.01-0.02; P < 0.001), in the superficial capillary plexus (β= 0.010; 95% CI, 0.002-0.019; P= 0.020), in the DCP (β= 0.02; 95% CI, 0.01-0.03; P < 0.001), and lower CC FVD% (β=-0.01; 95% CI,-0.03 to-0.001; P= 0.040) in the entire images. After they were fully adjusted, the parameters in the inner ring of the RPC, DCP, and CC FVD% were significantly associated with MAU (P < 0.05). Decrease in retinal and choroidal microcirculation in the optic nerve head was independently associated with renal dysfunction. Further longitudinal studies are needed to clarify the peripapillary vessel changes during CKD progression. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Association between choriocapillaris perfusion and axial elongation in children using defocus incorporated multiple segments (DIMS) spectacle lenses.

To investigate choroidal and ocular biological variables that influence axial length (AL) elongation in children wearing defocused incorporated multiple segments (DIMS) spectacle lenses. This cohort study included 106 myopic children aged 7-14 years with a 1-year follow-up. Participants were divided into two groups according to the increase in AL in one year: rapid (>0.2 mm) and slow (≤0.2 mm) axial elongation groups. Cycloplegic autorefraction and AL were measured at baseline and after 6 and 12 months. The area of choriocapillaris flow voids (FVs) and choroidal thickness (ChT) at baseline were measured. Univariate linear regression analysis showed that AL elongation were significantly associated with the FVs area (standardised β = 0.198, P < 0.05) and age (standardised β = -0.201, P < 0.05). Multiple linear regression showed that the FVs area, age, and average K reading were associated with AL elongation. Multiple logistic regression analyses showed that greater degrees of myopia and larger FVs areas were risk factors for rapid axial elongation, while older age, large pupil diameter and steeper cornea were protective factors. In estimating axial elongation, the FVs area alone demonstrated an area under the curve (AUC) of 0.672 (95% CI, 0.569-0.775, P < 0.01), and that of FVs area and other ocular variables was 0.788 (95% CI, 0.697-0.878, P < 0.001). Larger choriocapillaris FVs area at baseline may help to predict axial elongation in myopic eyes. The association between FVs area and axial elongation should be taken into consideration in further myopic cohort studies.

Change in three-dimensional choroidal vessel network after AR device assisted 1-hour visual task in 2D/3D mode in young healthy subjects.

The purpose of the study was to investigate the changes of choroidal blood perfusion in different layers and quadrants and its possible related factors after 1 h visual task by augmented reality (AR) device in two-dimensional (2D) and three-dimensional (3D) mode, respectively. Thirty healthy subjects aged 22-37 years watched the same video source in 2D and 3D mode separately using AR glasses for 1 h with a one-week interval. Swept-source optical coherence tomography angiography (SS-OCTA) was performed before and immediately after watching to acquire choroidal thickness (ChT), three-dimensional choroidal vascularity index (CVI) of large- and middle-sized choroidal vessels and choriocapillaris flow voids (FV%) at macular and peripapillary area. Near point of accommodation (NPA) and accommodative facility (AF) were examined to evaluate the accommodative ability. Pupil diameters by infrared-automated pupillometer under scotopic, mesopic and photopic condition were also obtained. Compared with pre-visual task, the subfoveal CVI decreased from 0.406 ± 0.097 to 0.360 ± 0.102 after 2D watching (p < 0.001) and to 0.368 ± 0.102 after 3D watching (p = 0.002). Pupil sizes under different illuminance conditions became smaller after both 2D and 3D watching (all p < 0.001). AF increased after both 2D and 3D watching (both p < 0.05). NPA receded in post-3D watching (p = 0.017) while a not significant tendency was observed in post-2D. A reduction in subfoveal choroidal blood flow accompanied with pupil constriction was observed immediately after 1 h visual task using AR glasses in 2D and 3D mode. Accommodative facility improved after 2D and 3D watching with AR glasses, whereas decrease in the maximum accommodation power was only found in 3D mode.

Состояние хориокапилляров у пациентов с парацентальной острой срединной макулопатией

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). Method. 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 &lt; 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 &lt; 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. Keywords: paracentral acute middle maculopathy; choriocapillaris; vessel density; optical coherence tomography angiography; retinal vein occlusion

Fully automatic segmentation and monitoring of choriocapillaris flow voids in OCTA images.

Optical coherence tomography angiography (OCTA) is a non-invasive ophthalmic imaging modality that is widely used in clinical practice. Recent technological advances in OCTA allow imaging of blood flow deeper than the retinal layers, at the level of the choriocapillaris (CC), where a granular image is obtained showing a pattern of bright areas, representing blood flow, and a pattern of small dark regions, called flow voids (FVs). Several clinical studies have reported a close correlation between abnormal FVs distribution and multiple diseases, so quantifying changes in FVs distribution in CC has become an area of interest for many clinicians. However, CC OCTA images present very complex features that make it difficult to correctly compare FVs during the monitoring of a patient. In this work, we propose fully automatic approaches for the segmentation and monitoring of FVs in CC OCTA images. First, a baseline approach, in which a fully automatic segmentation methodology based on local contrast enhancement and global thresholding is proposed to segment FVs and measure changes in their distribution in a straightforward manner. Second, a robust approach in which, prior to the use of our segmentation methodology, an unsupervised trained neural network is used to perform a deformable registration that aligns inconsistencies between images acquired at different time instants. The proposed approaches were tested with CC OCTA images collected during a clinical study on the response to photodynamic therapy in patients affected by chronic central serous chorioretinopathy (CSC), demonstrating their clinical utility. The results showed that both approaches are accurate and robust, surpassing the state of the art, therefore improving the efficacy of FVs as a biomarker to monitor the patient treatments. This gives great potential for the clinical use of our methods, with the possibility of extending their use to other pathologies or treatments associated with this type of imaging.

Artifact-Removed Quantitative Analysis of Choriocapillaris Flow Voids.

To investigate choriocapillaris flow voids (FV) with a new optical coherence tomography angiography (OCTA) image processing strategy that can eliminate artifacts caused by vitreous opacities, sub-retinal pigment epithelium fluid and deposits, and subretinal fluid (SRF) by thresholding the en-face OCT image of the outer retina. We retrospectively reviewed medical records of patients with drusen and patients with active central serous chorioretinopathy (CSC). FV number (FVn), average area (FVav), and maximum area (FVmax) and the percentage of nonperfused choriocapillaris area (PNPCA) obtained using the proposed strategy were compared with those obtained by removing only artifacts caused by the superficial capillary plexus (SCP). The SRF group included 21 eyes with active CSC and the drusen group included 29 eyes with nonexudative age-related macular degeneration. FVav, FVmax, FVn, and PNPCA obtained using the algorithm were significantly lower than those obtained by removing only SCP-related artefacts in both groups (all p<0.05). The algorithm was also able to remove 96.9% of artifacts secondary to vitreous opacities and all artifacts secondary to serous pigment epithelial detachments. Choriocapillaris nonperfusion areas on OCTA images may be overestimated in eyes with RPE abnormalities and SRF due to artifacts. These artifact areas on choriocapillaris OCTA images can be removed using thresholded images of the outer retina en-face OCT scans. Our new artifact-removal strategy is useful in the assessment of choriocapillaris FV in eyes with SRF, drusen, drusen-like deposits, and pigment epithelial detachment.

Repeatability of choriocapillaris flow voids by optical coherence tomography angiography in central serous chorioretinopathy.

To assess the repeatability of flow signal voids (FSV) measurements of the choriocapillaris (CC) and choroid (CH) in central serous chorioretinopathy (CSCR) by Swept-Source optical coherence tomography angiography (SS-OCTA). Cross-sectional study including 104 eyes of 52 patients with unilateral CSCR. Two consecutive macular 6x6 mm SS-OCTA scans (Plex Elite 9000; Zeiss, Dublin, CA) were obtained from the affected eyes with persistent subretinal fluid (SRF) (CSCR group) and the fellow unaffected eyes (control group). FSV area and the number of contours measurements were analyzed using three slabs: inner CC, outer CC and CH. The repeatability of the measurements was assessed with intraclass correlation coefficients (ICC) and coefficients of variation (CV). In the CSCR group, ICCs for the FSV area in the three slabs were all ≥0.859, observing higher values for the outer CC and the CH (0.959 and 0.964) than for the inner CC (0.859). Similar ICC values were obtained for the FSV area in control eyes, observing the highest values for the outer CC (0.949), followed by the CH (0.932) and inner CC (0.844). Regarding the FSV number of contours measurements, ICCs were higher for the outer CC and CH (0.949 and 0.932) than for inner CC (0.844). CV for the FSV area was 4.7%, 3.8% and 8.6% in the CSCR eyes and 4.8%, 3.9% and 9.3% in the control group for the inner CC, outer CC and CH respectively. SS-OCTA offers good repeatability to quantify macular FSV in CSCR eyes and fellow eyes.

Pigment epithelium and choroid changes in pachychoroid pigment epitheliopathy: A descriptive study

AbstractPurpose: To describe characteristic elementary lesions of retinal pigment epithelium and choroidal vascular parameters determined by swept source optical coherence tomography (SS‐OCT) and OCT‐angiography (OCT‐A) in eyes with pachychoroid pigment epitheliopathy.Methods: Twenty‐seven patients with retinal pigment epithelium (RPE) abnormalities associated to pachychoroid features, with no history or findings indicative of subretinal fluid or soft drusen were evaluated. All eyes underwent comprehensive ophthalmic examination, fundus photography, SS‐OCT and OCT‐A. After binarization of B‐scan images with ImageJ Software, the choroidal vascularity index (CVI), the choroidal vascularity proportion (CVP) and flow voids area were calculated.Results: A total of 27 eyes of 23 patients, 19 of whom were male (70.37%), with a mean age of 59.11 ± 12.76 years were enrolled in this study. We detected six different types of RPE lesions: focal disruption in ellipsoid and interdigitation zones in 18 eyes (66.66%), RPE elevation with microbreak appearance in 12 eyes (44.44%), RPE thickening in 10 eyes (37.03%), small pigment epithelium detachment in seven eyes (25.92%), RPE spike in five eyes (18.51%) and outer nuclear layer thinning in five eyes (18.51%). The subfoveal choroidal thickness (SFCT) was 399, 78 ± 88, 13 μm. The mean inner choroidal thickness was 87.18 ± 36.67 μm. The CVI was 65.28 ± 3.35%. The CVP was 59.10 ± 0.58% in the choriocapillaris and 59.69 ± 1.42% in the Haller layer. The total choriocapillaris flow void area was 39.87 ± 1.21%.Conclusions: SS‐OCT and OCT‐A are valuable diagnostic tools to characterize pigment epithelium and choroidal changes in PPE eyes.

Serial choriocapillaris flow changes in eyes with branched retinal vascular obstruction (BRVO).

To evaluate the choriocapillaris (CC) flow changes in branched retinal vascular obstruction (BRVO) on optical coherence tomography angiography (OCTA). Retrospective analysis of 29 patients with unilateral BRVO (58 eyes, including unaffected fellow eyes for controls). 4.5 x 4.5 mm macular scans were divided into 4 quadrants. Serial analyses were conducted on CC flow voids of the opposite quadrant to the active occluded area in BRVO eyes. Each of the quadrants were also compared to the occluded quadrant of resolved eyes and the contralateral quadrant of fellow eyes by matched data analysis. A regression analysis was performed on the several parameters (Choroidal thickness; CT, Choroidal vascularity index; CVI, Central macular thickness; CMT, The number of intravitreal injections) and CC flow voids. The CC flow void increased sequentially: The uninvolved quadrant of acute BRVO-affected eyes, that of resolved eyes after 3-month/1-year, the contralateral quadrant of fellow eye, the involved (occluded) quadrant of resolved eyes. There were significant correlations between initial CMT, the number of injections and the CC flow void of uninvolved quadrants (P = 0.025, 0.031, respectively), and between the involved (occluded) quadrants and fellow CT (P = 0.029). CC flow void of uninvolved macular areas decreased significantly in eyes with acute BRVO, suggesting that CC changes were limited to the blocked area and a compensatory mechanism would work in surrounding areas.

Short-term effect of orthokeratology lens wear on choroidal blood flow in children with low and moderate myopia

We investigated changes in choroidal vascularity and choriocapillaris blood perfusion during orthokeratology (Ortho-K) lens wear. Sixty-two children with low to moderate myopia were enrolled. The Ortho-K group (n = 42) continuously wore Ortho-K lenses for 3 months, and the controls (n = 20) wore single-vision distance spectacles. All of the patients were instructed to return for follow-up visits after 1 day, 1 week and 1 month and 3 months of treatment. The subfoveal choroidal thickness (SFChT), choroidal vascularity [including the total choroidal area, luminal area, stromal area, and choroidal vascularity index (CVI)] and percentage of choriocapillaris flow voids (FV%) were determined with a Cirrus HD-OCT instrument. Additionally, ocular parameters were measured. In the Ortho-K group, the SFChT significantly increased by 12.61 ± 5.90 μm, the CVI was significantly increased by 2.99 ± 2.07% and 3.01 ± 2.32% on the horizontal and vertical scans respectively, and the FV% was significantly decreased by 0.89 ± 0.34% from baseline at the 1-week visit (all p < 0.001). The choroidal parameters remained unchanged at the 1-month and 3-month follow-ups with respect to the 1-week follow-up. In the control group, the choroidal parameters did not change significantly at 1 month (all p > 0.05). At the 3-month visit, the changes in the axial length (AL) and vitreous chamber depth (VCD) were significantly greater in the control group than in the Ortho-K group (0.14 ± 0.23 and 0.03 ± 0.05 mm in AL, 0.15 ± 0.23 and 0.06 ± 0.03 mm in VCD respectively). Our longitudinal study showed several choroidal parameter changes in the early stage in Ortho-K lens wearers with low to moderate myopia, and these changes persisted over 3 months. We speculate that Ortho-K lenses regulate choroidal thickness and blood perfusion, affecting myopia development.