Retinal vascular metrics difference by comparison of two image acquisition modes using a novel OCT angiography prototype

LONGITUDINAL ANALYSIS OF MICROVASCULAR CHANGES IN SICKLE CELL DISEASE USING SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To analyze the changes in macular vascular densities (VDs) and foveal avascular zone (FAZ) over a 6-year period using swept-source optical coherence tomography angiography in patients with sickle cell disease compared with unaffected control subjects.

METHODS

Thirty eyes of patients with sickle cell disease and 12 eyes of unaffected control subjects matched for age and ethnicity were examined at a 6-year interval using the same imaging protocol, including ultra-wide-field angiography, swept-source OCT, and 3 × 3-mm optical coherence tomography angiography. The macular VD and FAZ were measured on ImageJ software according to previously reported algorithms.

RESULTS

In sickle cell eyes, the mean FAZ significantly increased ( P < 0.01), and the VD decreased in the foveal (within a circle of 1.5 mm in diameter around the foveal center) and temporal areas in both the superficial and the deep capillary plexuses ( P < 0.01). The VD did not change over time in the parafoveal area (annulus between two circles of 1.5 and 3 mm in diameter) and in the superior, inferior, and nasal sectors. No worsening of peripheral retinopathy was observed in the cohort during the follow-up, except for one eye that developed sea-fan. In the control eyes, no microvascular change was observed over time in FAZ size and VD.

CONCLUSION

These longitudinal optical coherence tomography angiography findings in patients with sickle cell disease showed an enlargement of the FAZ and a decrease in VD in the temporal and perifoveal regions despite the absence of progression of peripheral retinopathy, suggesting a worsening of the macular nonperfusion over time in sickle cell disease.

The Influence of Topical Perioperative Nepafenac on Retinal Vasculature Following Phacoemulsification Using Optical Coherence Tomography Angiography: A Randomized Clinical Trial

PURPOSE

To investigate topical nepafenac drops (TND) effect on retinal vasculature following uneventful phacoemulsification.

METHODS

54 eyes were randomly assigned to G1: TND 3 days preoperatively and 1 month postoperatively; G2: TND for 1 month postoperatively; and G3 no TND (control). BCVA, macular OCTA were compared baseline, 1 week and 1 month.

RESULTS

No statistically significant differences found between 3 groups in OCTA parameters during study visits. However, at 1 month (compared to baseline) there were a statistically significant increase in superficial capillary plexus (SCP) capillary vessel density (CVD) in G2 (p=0.036); increase in central foveal thickness (CFT) in G2 (p=0.011) and G3 (control) (p=0.001); and reduced number of patients with SCP disorganization in G2 (p=0.04). There were no significant correlation/association between most of OCTA parameters and final BCVA.

CONCLUSION

TND use perioperative did not show any effect on retinal OCTA microvasculature and might affect macular edema by other mechanisms.

In vivo assessment of associations between photoreceptors structure and macular perfusion in type 1 diabetes

PURPOSE

To explore the potential relationships between macular vascular network and different adaptive optics (AO) metrics in patients with type 1 diabetes mellitus (DM1) with no signs (NoDR) or mild non-proliferative diabetic retinopathy (NPDR).

DESIGN

Observational cross-sectional study.

METHODS

Forty eyes of consecutive patients with DM1 (12 NoDR and 28 NPDR) and 10 healthy age-matched control subjects were included. All patients and controls were imaged using AO retinal camera and PLEX Elite 9000 optical coherence tomography (OCT) angiography (OCTA). The AO outcome measures to evaluate the cone photoreceptor mosaic characteristics were as follows: (1) Cone density (CD); (2) Linear Dispersion Index (LDi) and (3) Heterogeneity Packing Index (HPi). The OCTA outcome measures included: (1) superficial capillary plexus (SCP) perfusion density (PD); (2) deep capillary plexus (DCP) PD and (3) the choriocapillaris (CC) flow deficit percentage (FD%).

RESULTS

NPDR group exhibited a close relationship between cone metrics and CC FD. Notably, CC FD% increase along with LDi (p=0.035), while the increasing CC FD% were associated with reducing CD (p=0.042) and the HPi (p=0.017). Furthermore, the OCTA parameters, including PD SCP and DCP, showed a significant negative correlation with CD.

CONCLUSIONS

Our results demonstrated the relationship between macular perfusion at both retinal and choroidal levels and the cone mosaic in patients with DM1 interpolating swept-source-OCTA and AO metrics. In NPDR eyes, the photoreceptor damage was accompanied by CC insufficiency since the early stages of the disease.

Short-term peripapillary structural and vascular changes following anti-VEGF vs. Dexamethasone intravitreal therapy in patients with DME

PURPOSE

To evaluate short-term peripapillary structural and vascular changes in DME after treatment with dexamethasone implant (DEX-I) and anti-VEGFs using OCT-A.

METHODS

Sixty-five patients with naïve center-involving DME were enrolled. 33 of sixty five patients (group 1) underwent with single DEX-I 0.7 mg (Ozurdex, Allergan, Inc., USA), 32 of sixty-five (group 2) underwent with intravitreal injection of aflibercept 0.5 mg (Eylea, Bayer, Genentech, San Francisco, USA). The OCT acquisition was completed at the following visits: (i) "T1 visit" corresponding to the intravitreal injection of DEX-I or aflibercept in patients with naïve center-involving DME (ii) "T2 visit" corresponding to the examination performed 2 weeks after intravitreal injection of aflibercept and 1 month after DEX-I. The parameters analyzed were: (i) RPC vasculature density (VD); (ii) peripapillary retinal nerve fiber layer (pRNFL) thickness, and (iii) intraocular pressure (IOP).

RESULTS

The RPC analysis showed a VD increase at T2 in both groups, although values did not reach statistical significance (48.12± 4.17 and 49.04 ± 4.23; P = 0.081 in Group 1 and 46.93± 3.16 and 47.17 ± 3.70; P = 0.087 in Group 2). Likewise, the pRNFL thickness and IOP fluctuations did not show statistically significant changes in in both groups among the different study visits.

CONCLUSIONS

After intravitreal injection (anti-VEGF or DEX-I), no significant short-term changes were found in peripapillary microvasculature, IOP and pRNFL thickness in diabetic eyes treated with anti-VEGF or DEX-I.

Qualitative and quantitative comparison of two semi-manual retinal vascular density analyzing methods on optical coherence tomography angiography images of healthy individuals

The aim of this study was to evaluate qualitative and quantitative differences in vascular density analysis of an established and a novel alternative for post-processing on optical coherence tomography angiography (OCTA) images in healthy individuals. OCTA examinations of 38 subjects were performed. After extracting the images, two semi-manual post-processing techniques, the already established Mexican hat filtering (MHF) and an alternative, the Shanbhag thresholding (ST) were applied. We assessed Vessel Density (VD), Skeleton Density (SkD) and Vessel Diameter Index (VDI). We analyzed the results in order to establish similarities or potentially relevant differences. Regarding SkD and VD, MHF generally gave higher values than ST. Simultaneously, mean values were also predominantly higher by MHF; however, standard deviations (SD) were higher by ST (range [mean ± SD]: 0.054 ± 0.038 to 0.134 ± 0.01 and 0.134 ± 0.095 to 0.362 ± 0.028 vs 0.012 ± 0.014 to 0.087 ± 0.03 and 0.039 ± 0.047 to 0.4 ± 0.095 for SkD and VD with MHF vs SkD and VD with ST, respectively). Values of VDI were considerably higher with ST than with MHF, while standard deviation was still significantly higher with ST (range [mean ± SD]: 2.459 ± 0.144 to 2.71 ± 0.084 and 2.983 ± 0.929 to 5.19 ± 1.064 for VDI with MHF and ST, respectively). The noise level reduction of the two methods were almost identical (noise levels: 65.8% with MHT and 65.24% with ST). Using MHF, the vascular network gets more fragmented by an average of 40% compared to ST. Both methods allow the segmentation of the vascular network and the examination of vascular density parameters, but they produce largely inconsistent results. To determine if these inconsistent results are clinically meaningful, and which method is more suitable for clinical use, our results provide further evidence that detailed understanding of the image analysis method is essential for reliable decision making for patients with retinal pathology. For longitudinal monitoring, use of the same image processing method is recommended.

Cortisol awake response imbalance as an indicator of acute central serous chorioretinopathy: Relationship with choriocapillaris and choroidal features

Purpose

The purpose of the present study was to measure in central serous chorioretinopathy (CSC) the salivary cortisol awake response (CAR) delta percentage (Δ%) variation, a distinct and robust indicator of cortisol rhythm during wakefulness, commonly proposed as a marker of hypothalamic-pituitary adrenal (HPA) axis activity, whose alteration is frequently associated with several adverse health outcomes.

Methods

In the present cross-sectional observational study, salivary CAR Δ% variation was assessed in 17 adult male subjects affected by acute naïve CSC and compared to 17 matched healthy controls. Choroid vasculature metrics were assessed in the study population by measuring the subfoveal choroidal thickness (FCT) and the choroidal vascularity index (CVI) by the imaging technique of enhanced-depth imaging spectral-domain optical coherence tomography (EDI-SD-OCT). Furthermore, flow signal void area features of the choriocapillaris were evaluated in the study population using OCT angiography (OCTA).

Results

Both the control and CSC groups showed a physiological cortisol increase that occurred during the first 30 min after awaking. However, CSC adult male patients showed remarkably blunted CAR Δ% variation in comparison with controls, which might reflect a CSC-related imbalance of HPA axis activity. Statistically significant correlations were shown by Pearson’s correlation test between salivary CAR Δ% and the selected choroidal and choriocapillaris imaging biomarkers (FCT, CVI, and flow signal void area) in the study population.

Conclusion

In conclusion, alterations of the CAR Δ% increase, associated with choroidal-retinal metrics, might provide a window into the physiopathology of acute CSC, suggesting a possible common factor to explain the association between stress and CSC.

Evaluation of macular microvascular density using optical coherence tomography angiography in patients with Posner-Schlossman syndrome

BACKGROUND

Optical coherence tomography angiography (OCTA) is a novel technology that provides a noninvasive, dye-less method to visualize the blood vessels of the retina. In the present study, we investigate macular microvascular density and the correlation of ocular and demographic factors using OCTA in Posner-Schlossman syndrome (PSS) patients.

METHODS

This is a prospective observational study. All PSS patients and age- and sex-matched healthy subjects underwent complete ophthalmologic examination, and RE, BCVA, IOP, CCT, AL, CMT, GCIPI, RNFL, C/D ratio were recorded. The whole-image vessel density (wiVD) and whole-image perfusion density (wiPD), three-circle (1 mm central ring, 3 mm inner ring, 6 mm outer ring), and four-quadrant segmental VD and PD were calculated.

RESULTS

Seventeen PSS patients and 17 healthy subjects were enrolled in this study. The mean age was 42.65 ± 11.22 years in PSS patients and 42.71 ± 10.50 years in healthy controls. IOP, CCT, and C/D ratio were higher in PSS-attacked eyes, and BCVA, OPP and RNFL thickness was lower than those in the fellow eyes (p < 0.05). BCVA and OPP were improved in the PSS-attacked eyes in intermittent period (p < 0.05). The wiVD and wiPD were lower in the PSS-affected eyes than in the fellow eyes and in the control eyes in the PSS-attacked period (p < 0.05). All segmental VD and PD was lower in the PSS affected eyes than in the healthy control eyes (p < 0.05). In intermittent period, the wiVD and wiPD were lower in the PSS-affected eyes than in the fellow eyes (p < 0.05). Age, CCT, and SSI were associated with macular wiVD and wiPD in PSS attacked period. Age and CCT were associated with macular wiVD and wiPD in PSS intermittent period.

CONCLUSION

Decreased macular superficial VD and PD was found in patients with Posner-Schlossman syndrome in attacked period and in remission. Macular wiVD and wiPD were associated with age, CCT and SSI in PSS patients.

Analysis of Optic Nerve in Adults With Amblyopia Using OCTA

Objective

The aim was to quantify and compare papillary and peripapillary vessel density in amblyopic eyes of adults and age-matched controls.

Methods

This cross-sectional study involved 20 eyes from 10 subjects with anisometropic amblyopia and 12 eyes of 6 age- and gender-matched healthy controls. Optical coherence tomography angiography (OCTA) was performed on all participants. SPSS 20 was used for data analysis.

Results

The mean subject age was 35.7 ± 10.04 years (range 18–47) in the amblyopia group and 34.67 ± 6.92 years (range 23–42) in the control group. The diopter of amblyopia ranges from +3 to +5 ds. The mean inside optic disk capillary vessel density (CVD) was 41.88 ± 6.55% in amblyopic eyes, 49.23 ± 6.55% in fellow eyes, and 50.23 ± 4% in control eyes (p < 0.05). The mean inside optic disk all vessel density (AVD) was 52.97 ± 6.71% in amblyopic eyes, 59.87 ± 4.59% in fellow eyes, and 60.45 ± 2.8% in control eyes (p < 0.05). The amblyopic eye of participants showed a decrease in vessel density in the inside optic disk than in the fellow eyes and healthy subjects.

Conclusion

Our present study revealed lower vessel density inside the optic disc of adult patients with anisometropic amblyopia. However, further studies are really needed to determine the clinical relevance of this finding.

Towards standardizing retinal optical coherence tomography angiography: a review

The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.

OCTAVA: An open-source toolbox for quantitative analysis of optical coherence tomography angiography images

Optical coherence tomography angiography (OCTA) performs non-invasive visualization and characterization of microvasculature in research and clinical applications mainly in ophthalmology and dermatology. A wide variety of instruments, imaging protocols, processing methods and metrics have been used to describe the microvasculature, such that comparing different study outcomes is currently not feasible. With the goal of contributing to standardization of OCTA data analysis, we report a user-friendly, open-source toolbox, OCTAVA (OCTA Vascular Analyzer), to automate the pre-processing, segmentation, and quantitative analysis of en face OCTA maximum intensity projection images in a standardized workflow. We present each analysis step, including optimization of filtering and choice of segmentation algorithm, and definition of metrics. We perform quantitative analysis of OCTA images from different commercial and non-commercial instruments and samples and show OCTAVA can accurately and reproducibly determine metrics for characterization of microvasculature. Wide adoption could enable studies and aggregation of data on a scale sufficient to develop reliable microvascular biomarkers for early detection, and to guide treatment, of microvascular disease.

Relationship of Choroidal Vasculature and Choriocapillaris Flow With Alterations of Salivary α-Amylase Patterns in Central Serous Chorioretinopathy

Purpose

An abnormality in choroidal vasculature is a known factor in the pathogenesis of central serous chorioretinopathy (CSC), a chorioretinal disease affecting mostly middle-aged males. The purpose of the present study was to investigate the role of the autonomic nervous system (ANS) in the pathophysiology of CSC.

Methods

This was a cross-sectional observational study in which characteristic choroidal vasculature metrics were assessed by measuring the subfoveal choroidal thickness (FCT) and the choroidal vascularity index (CVI) using the imaging technique of enhanced-depth imaging spectral-domain optical coherence tomography (EDI-SD-OCT). Furthermore, flow signal void area features were also evaluated in the study population using OCT angiography (OCTA). Diurnal patterns of salivary α-amylase (a-AMY) production, proposed as a marker of autonomic activity, were assessed in an adult male study population affected by acute naïve CSC in comparison with matched healthy controls.

Results

Results include an overall higher diurnal output of salivary a-AMY production, which is in line with the phenomenon of a sympathetic “drive” playing a role in the pathophysiology of CSC, and a flattened diurnal percentage variation in α-AMY in CSC-affected subjects. Furthermore, Pearson's coefficient test revealed statistically significant correlations between salivary α-AMY diurnal percentage variation and selected choroidal imaging biomarkers (FCT, CVI, and flow signal void area). Finally, multiple linear regression analysis identified salivary α-AMY diurnal percentage production as the sole predictor of the CVI and flow signal void area in the study population.

Conclusions

Autonomic nervous system dysregulation was highlighted in CSC patients.

Choriocapillaris Vascular Density Changes: Healthy vs. Advanced Exudative Age-Related Macular Degeneration Previously Treated with Multiple Anti-VEGF Intravitreal Injections

Purpose: To assess choriocapillaris vascular density (VD) in healthy and advanced exudative age-related macular degeneration (ae-AMD) patients by new full-range optical coherence tomography angiography (OCT-A). Method: In this observational, cross-sectional study, 21 healthy and 21 ae-AMD eyes, already treated with anti-VEGF, were enrolled. Angio-View retina patterns centered on fovea (6.4 × 6.4 mm) were acquired for all participants using Solix full-range OCT (Optovue Inc., Freemont, CA, USA). The main outcome was to compare choriocapillaris VD between healthy and ae-AMD eyes. Automated measurements of whole image choriocapillaris VD (%) and fovea grid-based (%) were collected for the analysis. Angio-View patterns were used to assess the flow area (mm²) of macular neovascularization (MNV) by contour flow measure algorithm. Best-corrected visual acuity (BCVA) of both groups was also used for the statistical analysis. Results: The mean age was 60.9 (±8.3) in healthy and 73.33 (±15.05) in ae-AMD eyes. The mean BCVA (ETDRS letters) was 98.47 (±1.50) in healthy and 7.04 (±5.96) in ae-AMD eyes. The Mann–Whitney test comparing choriocapillaries VD for whole and fovea healthy and ae-AMD eyes showed statistical significance (p < 0.0001 (t = 4.91; df = 40) and p < 0.0001 (t = 6.84; df = 40), respectively). Regarding, the correlation between MNV and VD of choriocapillaries, neither whole nor fovea areas were statistically significant (F = 0.38 (R² = 0.01) and 1.68 (R² = 0.08), respectively). Conclusions: Choriocapillaris VD showed a statistically significant reduction in comparison to healthy eyes in ae-AMD eyes. Choriocapillaris impairment can be seen in the early phase of MNV pathogenesis.