The recent introduction of optical coherence tomography angiography (OCTA) has remarkably expanded our knowledge of the choroid through in vivo investigation of the anatomical and pathological ...features of this important vascular layer. New insights elucidating the morphological features of the choroid, in both physiological and pathological conditions, indicate that this vascular structure plays a crucial role in many chorioretinal disorders. In this article, a review of the salient histological and anatomical features of the choroid, essential for the proper interpretation of in vivo imaging, is followed by a discussion of the fundamental principles of OCTA and the application of this advanced imaging modality to study and understand the choroid. The current limitations of OCTA and potential advancements that may improve the widespread adoption of this tool are also discussed. A detailed review of the OCTA features of the choroid in the healthy eye is followed by relevant findings in major chorioretinal diseases, including age-related macular degeneration, central serous chorioretinopathy, uveitis, and inherited retinal disorders.
The purpose of this study was to compare the choriocapillaris plexus in eyes with intermediate AMD (iAMD), with or without neovascular AMD in the fellow eye, using optical coherence tomography ...angiography (OCTA).
We collected data from 42 eyes with iAMD from 42 patients who had obtained OCTA. This cohort was divided into two subgroups according to the status of the fellow eye, yielding a group of 20 cases with bilateral intermediate AMD (bilateral iAMD group) and 22 cases with neovascular AMD in the fellow eye (unilateral iAMD group). An additional control group of 20 eyes from 20 healthy subjects was included for comparison. Main outcome measures were: (1) the percent of nondetectable perfused choriocapillaris area and (2) the average choriocapillaris signal void size.
No differences in the percent of nondetectable perfused choriocapillaris area were found among the three groups (2.3 ± 1.4% in the unilateral iAMD group, 1.5 ± 0.9% in the bilateral iAMD group, and 1.7 ± 1.4% in the control group, respectively). The average choriocapillaris signal void size, however, was significantly increased in unilateral iAMD eyes (293.7 ± 71.2 μm2) compared to both bilateral iAMD (241.5 ± 51.6 μm2, P = 0.031) and control (212.7 ± 48.6 μm2, P = 0.001) eyes.
Intermediate AMD eyes of patients with neovascular AMD in the fellow eye have an increased average choriocapillaris signal void size compared to eyes without neovascular AMD in the fellow eye. If replicated in future studies, choriocapillaris signal void size may prove to be a useful parameter for evaluating eyes with AMD.
To evaluate the correlation between the choriocapillaris (CC) flow alterations around geographic atrophy (GA) and the GA yearly growth rate (yGR) in patients with dry age-related macular degeneration ...(AMD).
We retrospectively reviewed and analyzed spectral domain optical coherence tomography (SD-OCT) and SD-OCT angiography images of consecutive patients with GA acquired using the Cirrus OCT at the Doheny Eye Centers between 2015 and 2017. All eligible patients had one 6 x 6 mm OCTA scan acquired during the first visit (considered as baseline) and two fovea-centered 512 x 128 macular cubes (6 x 6 mm) acquired at baseline and after a minimum of 12 months.
The fundus images from the OCT volumes were used to manually delineate the GA area and calculate the yGR after square root transformation. The en-face angiogram at the level of the CC was analyzed for the percentage of flow voids (FV) outside the atrophic lesion (FVOUT) and in the para- and peri-atrophy regions (FV500 and FV1000 respectively; two concentric 500 μm wide rings around the atrophy edge). These values, together with the difference between FV500 and FV1000 (ΔFV), were then correlated with the corresponding yGR.
Thirty-three eyes of 23 patients were eligible for the analysis. The mean yGR was 0.23 ± 0.17 mm/years. At baseline, the mean FVOUT was 41.86 ± 2.71%, while FV500 and FV1000 were 46.4 ± 4.17% and 42.51 ± 2.65% respectively. The mean ΔFV was 3.89 ± 2.6%. While in the univariable analysis, the yGR was significantly associated with FV500 and with ΔFV (both p < 0.001), in multivariable model the association remained significant only with ΔFV (p < 0.001).
Our study reports a correlation between the CC flow impairment around the atrophic lesions and their yGR in patients with GA. If replicated in future longitudinal studies, the choriocapillaris FV in the para-and peri-atrophy regions may prove to be useful parameters for evaluating the prognosis of these eyes.
To quantitate regional differences in the choriocapillaris (CC) of patients with intermediate age-related macular degeneration (iAMD), using swept-source optical coherence tomography angiography ...(SS-OCTA) imaging.
Cross-sectional study.
Subjects were imaged with the SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc, Dublin, California, USA). The CC en face images were first compensated for the signal attenuation caused by drusen by using the structural information from the same slab. Subsequently, for each eye, 2 compensated CC en face images generated from 2 different OCTA volume scan sets were registered and averaged. The averaged CC images were then exported to ImageJ and binarized for subsequent quantitative analysis. In addition to the analysis of the whole averaged CC en face image in iAMD eyes, quantitative analysis was also performed in 3 different regions: (1) drusen region, (2) 150-μm-wide ring around the drusen border, and (3) drusen-free region.
Thirty eyes (30 patients) with iAMD and 30 healthy eyes from 30 controls were enrolled. Compared with controls, iAMD eyes displayed a lower number of signal voids (median and interquartile range IQR: 2561 and 2343-2746 vs 2734 and 2558-2834; P = .013), a greater signal void average size (median, IQR: 581.9 μm2, 466.1-726.9 μm2 vs 503.8 μm2, 429.1-576.8 μm2; P = .027), and a greater total signal void area (median, IQR: 26.0%, 22.1%-29.6% vs 23.8%, 21.2%-26.4%; P = .038). In multiple regression analysis, the presence of iAMD was not significantly associated with any of the CC variables. By contrast, the drusen region area was significantly associated with CC alterations. In the evaluation of the iAMD group, both the area underneath drusen and the 150-μm-wide ring region around drusen were characterized by an increased total signal void area (P = .005 and P = .045, respectively) vs the drusen-free region.
Intermediate AMD eyes demonstrated increased CC flow impairment, which co-localizes to the area of CC beneath and immediately surrounding drusen.
Imaging and histopathological studies have demonstrated that structural changes of the retina affect subjects with Alzheimer's disease (AD) or mild cognitive impairment (MCI). The aim of this study ...was to quantitatively investigate the retinal vessels in these disorders, using dynamic vessel analyzer (DVA) and optical coherence tomography angiography (OCTA) analysis. Twelve subjects with AD, 12 subjects with MCI, and 32 gender- and age-matched controls were prospectively enrolled. Mean ± SD age was 72.9 ± 7.2 years in the AD group, 76.3 ± 6.9 years in the MCI group, and 71.6 ± 5.9 years in the control group (p = 0.104). In the DVA dynamic analysis, the arterial dilation was decreased in the AD group (0.77 ± 2.06%), in the comparison with the control group (3.53 ± 1.25%, p = 0.002). The reaction amplitude was decreased both in AD (0.21 ± 1.80%, <0.0001) and MCI (2.29 ± 1.81%, p = 0.048) subjects, compared with controls (3.86 ± 1.94%). OCTA variables did not differ among groups. In the Pearson correlation analysis, amyloid β level in the cerebrospinal fluid was directly correlated with the arterial dilation (R = 0.441, p = 0.040) and reaction amplitude (R = 0.580, p = 0.005). This study demonstrate that Alzheimer's and MCI subjects are characterized by a significant impairment of the retinal neurovascular coupling. This impairment is inversely correlated with the level of amyloid β in the cerebrospinal fluid.
Purpose
To quantify the shrinking in outpatient and intravitreal injections’ volumes in a tertiary referral retina unit secondary to virus causing coronavirus disease 2019 (COVID-19).
Methods
In this ...retrospective cross-sectional study, we reviewed the charts of all patients who had a visit at a medical retina referral center during the Italian quarantine (from 9th of March 2020 to 3rd of May 2020). Number and characteristics of these data were compared with data from the same period in 2019 (from 9th of March 2019 to 3rd of May 2019).
Results
In the 2019 study period, there were 303 patients attending clinic (150 males, 153 females). In the 2020 study period, patients decreased to 75 (48 males, 27 females;
P
= 0.022 comparing gender prevalence between the two periods) with an overall reduction of 75.2%. Mean ± SD age was 71.4 ± 14.3 years (range 25–93 years) in the 2019 study period and 66.7 ± 13.1 years (range 32–91 years) in the 2020 study period (
P
= 0.005). The largest drop in outpatient volume was recorded in AMD patients (− 79.9%). Regarding the intravitreal treatments, there were 1252 injections in the 2019 period and 583 injections in the 2020 period (− 53.6% in injections). The drop in intravitreal treatments was larger in patients with posterior uveitis, retinal vein occlusion, and diabetes (− 85.7%, − 61.9%, and − 59.6%, respectively).
Conclusion
The volume of outpatient visits and intravitreal injections declined during the COVID-19 quarantine. The short- and long-term impacts are that routine in-person visits and intravitreal injections are expected to increase after the quarantine and, even more, after the pandemic.
To evaluate the topographic distribution of the choriocapillaris (CC) flow deficits in a population of healthy subjects.
Using a swept-source optical-coherence tomography angiography (SS-OCTA) ...device, two repeated volume 6 x 6 mm and 3 x 3 mm scans were acquired in healthy subjects at the Doheny-UCLA Eye Centers. The en-face CC angiogram was binarized and analyzed for percentage of flow deficits (FD%) using a grid of progressive, concentric rings covering a circular area with a diameter of 2.5 mm (in the 3 x 3 mm scans) and 5 mm (in the 6 x 6 mm scans). The FD% for each ring was plotted against the distance from the fovea. The linear trendline of the resulting curve was analyzed and the slope (m) and intercept (q) were computed.
Seventy-five eyes of 75 subjects were enrolled and divided into three subgroups based on age (year ranges: 21-40, 41-60 and 61-80). For the entire cohort and within each subgroup, there was a significant association between distance from the fovea and FD% in both 3X3 mm and 6X6 mm scans, with flow deficits increasing with closer proximity to the foveal center. Age was a significant predictor for both m and q for both scan patterns, with older subjects showing a steeper slope.
In SS-OCTA images, the topographic distribution of CC flow deficits varies with distance from the fovea and age. In particular, the FD% tends to decrease from the fovea towards the periphery, with a steeper decline with advancing age. These normal trends may need to be accounted for in future studies of the CC in disease.
The aim of this study was to explore whether rotational three-dimensional (3D) visualization of optical coherence tomography angiography (OCTA) volume data may yield valuable information regarding ...diabetic retinal microaneurysm (MA) characteristics. In this retrospective, observational study, we collected data from 20 patients (20 eyes) with diabetic retinopathy. Subjects were imaged with the SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). The OCTA volume data were processed with a volume projection removal algorithm and then exported to imageJ in order to obtain a 3D visualization of the analyzed MAs. The rotational three-dimensional OCTA images were qualitatively and quantitatively investigated. A total of 52 MAs were included in the analysis. On rotational 3D OCTA images, the number of vessels associated with each MA varied between 1 and 4, and most MAs (59.6%) were associated with 2 vessels. Moreover, in 20 MAs (38.4%) these vessels seem to originate from the SCP, while 26 MAs (50.0%) had associated vessels originating from the DVC, and 6 MAs had associated vessels arising from both the SCP and DVC (11.6%). Most MAs (31/52) had a 'saccular' shape. The number of retinal layers occupied by each MA ranged between 1 and 3 and the inner nuclear layer was the retinal layer most frequently occupied by MAs. In conclusion, this study used an algorithm to obtain rotational three-dimensional visualization of retinal MAs. The MAs' architecture is complex and 3D visualization may clarify the true vascular origin of these lesions, which is often mistaken using en face OCTA images.
To investigate alteration in superficial and deep retinal vascular densities and choroidal thickness, in patients affected by early and intermediate age-related macular degeneration (AMD).
All ...patients had undergone optical coherence tomography angiography (OCTA). All eyes were grouped into two stages: "early AMD" and "intermediate AMD." Outcome measures were superficial vessel density, deep vessel density, and choroidal thickness. A control group of healthy subjects was selected for the statistical comparisons.
A total of 37 eyes of 37 dry AMD patients were enrolled for the study. Fourteen of 37 eyes were classified as having early AMD, the remaining 23 of 37 eyes were classified as being affected by intermediate AMD. Superficial and deep vessel densities were 39.21% ± 10.67% and 43.84% ± 11.57%, respectively, in the control group and 28.30% ± 10.73% and 36.41% ± 12.30%, respectively, in AMD patients (P = 0.001 and P = 0.017, respectively). Choroidal thickness was significantly reduced in AMD patients.
In the last years, several studies have reported vascular factors playing an important role in AMD pathogenesis. We demonstrated that both superficial and deep retinal plexuses are altered among patients affected by AMD. Interestingly, this alteration starts immediately at the intermediate AMD stage and also the choroidal thickness reduction.
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