Foveal Avascular Zone Size Research Articles

Retinal vascular changes after Silicon Oil removal in the Eye with Rhegmatogenous Retinal detachment

BackgroundThis study aims to examine vessel density changes in the optic nerve and macula following silicone oil removal (SOR) surgery in eyes with rhegmatogenous retinal detachment (RRD) at different time points by Optical Coherence Tomography Angiography (OCTA) in compared to the contralateral eye.MethodsA total of 43 eyes from 43 patients with silicone oil in their eyes for 3–9 months underwent OCT-A using AngioVue and optic disc-associated vessel density (VD) and thickness, macular-associated VD and thickness, Foveal avascular zone (FAZ) area, FAZ perimeter (PERIM), Acircularity index (AI), vessel density within a 300 μm wide region of the FAZ were compared between eyes. OCTA scans were performed one week before SOR and one month and three months after SOR.ResultsThe mean age of participants was 52.8 years (SD = 15.85) and a median visual acuity was 0.8 (range: 0.5-1.0). Notably, male participants constituted 67.4% of the sample. The preoperative mean value BCVA (logMAR) of patients was 0.73, and 3 months post-oil removal was 0.7727. Regarding optic disc parameters, RNFL thickness and vessel density (VD) measurements Peripapillary, whole disc, inside disc, and Disc Angio (superior, Nasal, inferior, temporal) did not change.In analyzing macular thickness parameters, all of them (Whole and Fovea, parafoveal, and Perifovea) remained unchanged. Examining macular vessel density parameters revealed no significant changes across superficial and deep retinal layers. Finally, the comparison of the foveal avascular zone (FAZ) area and flow density (FD) parameters demonstrated consistent measurements with non-significant alterations observed in FAZ size (p = 0.6) and FD values (p = 0.49) over the monitored duration.ConclusionThere was no change in peripapillary VD and macular vessel density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) after silicone oil removal. FAZ and full retinal thickness remained stable 3 month after SOR. Clinical trial number: Not applicable.

The Role of Widefield Optical Coherence Tomography Angiography in Assessing the Severity of Diabetic Retinopathy.

Physicians need an accurate understanding of diabetic retinopathy (DR) severity to optimally manage patients. The aim of this prospective study is to correlate the severity of macular and peripheral retinal vascular abnormalities seen on widefield (WF) optical coherence tomography angiography (OCTA) with DR grading based on WF fundus photography. The study included 150 eyes from 82 patients with treatment-naïve DR. All patients were imaged with WF fundus photography and swept-source WF OCTA. Quantitative and qualitative analyses of the foveal avascular zone (FAZ) size and shape, and measurement of capillary nonperfusion (CNP) areas, were performed from the OCTA images. The mixed-effects model was used to compare the DR grading from WF photography with the vascular changes seen on WF-OCTA, and Bonferroni correction was applied to the gradings. The mean [± standard deviation (SD)] age of patients was 55.5 (± 9.4) years. The WF-OCTA showed that an increasing size of the FAZ (from 0.442 (± 0.059) µm to 0.933 (± 0.086) µm) correlated with increasing severity of the DR (as determined with WF photography). The deep capillary plexus, FAZ size, and CNP areas in eyes with proliferative diabetic retinopathy (PDR) differed from those with mild nonproliferative diabetic retinopathy (NPDR) (p < 0.001). Most eyes with severe nonproliferative DR were found to have CNP in four quadrants [superficial capillary plexus (SCP) 60%, deep capillary plexus (DCP) 50%]. The WF-OCTA detected subtle neovascularization of the disc (NVD) in 7 eyes (10%) and neovascularization elsewhere (NVE) in 13 eyes (18%) that had been diagnosed with only moderate NPDR on WF photography. FAZ and CNP areas as measured by WF-OCTA correlate with DR severity. WF-OCTA can also detect subtle NVE and NVD that cannot be seen with fundus photography.

Clinical observation of the subthreshold micropulse laser combined with ranibizumab for treatment of diabetic macular edema

Objective: To evaluate the efficacy and safety of the subthreshold micropulse laser (SMPL) combined with ranibizumab in treating diabetic macular edema (DME). Methods: This was a prospective randomized controlled study. Patients diagnosed with DME in the Ophthalmology Department of Beijing Hospital were enrolled from January 2020 to December 2022. Patients were randomized in a ratio of 1∶1 using a table of random numbers into the ranibizumab monotherapy group and the SMPL combined with ranibizumab therapy group. We compared the changes of best-corrected visual acuity, central macular thickness measured by optical coherence tomography and optical coherence tomography angiography parameters, including the vessel density of the superficial and deep capillary plexus (DCP), foveal avascular zone size and peripapillary vessel density, at baseline, 6 and 12 months after the treatment. After 12 months of follow-up, fundus fluorescein angiography results, adverse events, and the number of injections or laser therapies were recorded. The Fisher's exact test and group t-test were used for statistical analysis. Results: Seventy-two patients (72 eyes) were enrolled, with a mean age of (61.1±8.2) years. Patients in the combination therapy group included 19 males and 17 females, while patients in the ranibizumab monotherapy group were 17 males and 19 females. There was no statistically significant difference in baseline characteristics between the two groups (P>0.05). A significant improvement in best-corrected visual acuity was shown in both groups at 6 and 12 months [(58.5±12.9) and (58.2±12.2) ETDRS letters in the combination therapy group, and (63.3±13.1) and (63.8±12.5) ETDRS letters in the ranibizumab monotherapy group]. A significant reduction in central macular thickness was shown in both groups at 6 and 12 months [(451.0±185.5) and (380.4±159.3)μm in the combination therapy group, and (387.5±135.5) and (372.8±146.1)μm in the ranibizumab monotherapy group]. However, there was no significant difference between groups at each timepoint (all P>0.05). At 12 months, the vessel density of the superficial capillary plexus showed no statistical difference compared to the baseline value in each group or between groups (42.6%±5.9% in the ranibizumab monotherapy group and 42.2%±5.5% in the combination therapy group, P>0.05). The vessel density of the DCP in the combination therapy group significantly increased to 47.5%±5.6% at 12 months, significantly different from that in the ranibizumab group (43.4%±5.1%; P<0.05). The foveal avascular zone size in the ranibizumab monotherapy group reduced to (0.32±0.13) mm2, significantly different from that in the combination therapy group [(0.34±0.16) mm2] at 12 months (P<0.05). Patients in the ranibizumab monotherapy group received (7.3±2.5) intravitreal injections, while patients in the combination therapy group received 3 injections. No unfavorable outcomes on fundus fluorescein angiography or systemic or topical severe adverse events were observed during the follow-up. Conclusions: The SMPL combined with intravitreal ranibizumab injections was effective and safe in treating DME patients. The combination treatment significantly reduced the number of injections and improved the vessel density of the DCP and macular ischemia, compared to the ranibizumab monotherapy.

Quantitative Analysis of Different Foveal Avascular Zone Metrics in Healthy and Diabetic Subjects

The primary aim of this study was to assess the size and shape of the Foveal Avascular Zone (FAZ) in patients with type 2 diabetes mellitus compared to healthy subjects. The study used 80 OCTA images from the FAZID dataset. The FAZ size was measured by its area, perimeter, and maximum/minimum Feret diameters. The shape was assessed using the axial ratio, circularity, roundness, and solidity. These metrics were calculated automatically using Matlab® R2020b. Statistical analysis was performed using SPSS statistical software version 28.0, with a p-value of less than 0.01 considered significant. The results showed that the FAZ area was significantly larger in diabetic eyes (mean = 0.50 mm2) compared to control eyes (mean = 0.37 mm2), with a p-value of less than 0.01. Both the maximum and minimum diameters of the FAZ were also significantly larger in diabetic groups compared to the control group. Parameters associated with FAZ’s shape were significantly smaller in the diabetic groups than in the control group, except for the axial ratio. The main finding of this study is that diabetic eyes without clinically detectable diabetic retinopathy exhibit morphological changes and irregularities at the FAZ border.

Investigation of factors that may affect the foveal avascular zone: An optical coherence tomography angiography study

SIGNIFICANCE An understanding of factors that affect the foveal avascular zone (FAZ) in healthy eyes may aid in the early identification of patients at risk of retinal pathology, thereby allowing better management and preventive measures to be implemented. PURPOSE The size and shape of the FAZ can change due to retinal diseases associated with oxidative stress, including diabetic retinopathy, glaucoma, and macular degeneration. This study aimed to assess the relationship, if any, between factors that may affect the superficial FAZ (i.e., vessel density, vessel perfusion, overweight/obesity) and possible links with macular pigment optical density in young, healthy participants. METHODS One hundred thirty-nine participants aged 18 to 35 years were recruited to this cross-sectional study. The superficial FAZ area, foveal vascularity, and central macular thickness (CMT) were assessed using the Cirrus 5000. Health parameters, body mass index, trunk fat %, and macular pigment were analyzed to determine possible associations with the superficial FAZ. RESULTS Mean FAZ area was 0.23 ± 0.08 mm2. Females had a significantly larger mean FAZ area than males (p=0.002). The FAZ area was positively correlated with body mass index (Pearson's r = 0.189, p=0.026). Significant correlates of the FAZ area in the multivariate model included vessel perfusion (central), CMT, and trunk fat %, collectively explaining 65.1% of the overall variability. CONCLUSIONS Study findings suggest that reduced vessel perfusion, thinner CMT, and higher trunk fat % are plausible predictors of a larger FAZ area in healthy Caucasian adults. Low macular pigment optical density was, however, not associated with increased FAZ size in young healthy eyes. Noninvasive optical coherence tomography angiography testing, in association with these predictors, may aid in the early detection and monitoring of retinal diseases associated with oxidative stress.

Evaluation of glaucomatous macular and optic nerve vascular damage by optical coherence tomography angiography

Purpose The aim of this study was to compare the macular and optic nerve head vessel perfusion density in mild primary open-angle glaucoma (POAG) and moderate–severe POAG patients to normal eyes as a control cohort. Patients and methods This is a retrospective comparative case–control study that included 80 eyes of 46 participants. The study included 60 eyes of 36 POAG patients and 20 eyes of 10 healthy participants (control group). The patients underwent 3.0×3.0 mm optical coherence tomography angiography (OCTA) scans centered on the macula and 4.5×4.5 mm scans on the optic disc. Results The OCTA scans of the glaucomatous eyes revealed a reduction in microvasculature in the peripapillary area, which was absent in the control cohort. The whole disc vessel density (VD) was significantly less in the glaucomatous eyes (mean=38.02±8.74) compared to the control cohort (mean=50.41±2.58, P&lt;0.001). The severity of glaucoma was linked to a decrease in macular VD percentage, with a mean superficial VD of 36.09±5.67 in the glaucoma cohorts and 46.64±5.53 in the control cohort (P&lt;0.001), which was more pronounced than in the deep layer (P&lt;0.008). There was no statistically significant difference in the foveal avascular zone size between the control and glaucoma cohorts at any stage (P=0.999). Conclusion The OCTA vascular density accurately distinguished the glaucoma from healthy eyes, with superior performance in the peripapillary region. The foveal avascular zone size did not indicate glaucoma severity. The OCTA noninvasive assessment of the capillary networks showed a potential for managing the glaucoma patients by characterizing the retinal vascular changes.

The long-term influence of perinatal factors on macular morphology and vessel density in preterm children

BackgroundIncreased survival rate of extremely preterm children is associated with a higher risk of retinopathy of prematurity (ROP) and long-term sequelae, which implicate retinal changes. PurposeTo assess an influence of perinatal characteristics on morphology and retinal vascularity of the macula in preterm children. MethodsA cohort of 123 preterm children at the age of 10.5 years (IQR: 8.12-12.77) was prospectively assessed. Optical coherence tomography angiography (OCTA) was performed using RTVueXR Avanti. Foveal thickness, parafoveal thickness, size of foveal avascular zone (FAZ), superficial and deep vessel density, central choroidal thickness (CCT) were analyzed. The associations between OCTA results and perinatal factors, including the presence of ROP and therapy requirements were assessed in preterm children. ResultsSignificantly smaller FAZ, higher foveal thickness and vessel density were noted in children with ROP, Respiratory Distress Syndrome, Bronchopulmonary Dysplasia, required erythropoietin, transfusion or steroids. Foveal thickness was increased in children with ROP (p < 0.001) and following laser treatment (p < 0.05). Thinner CCT was noted in children with a history of sepsis (p < 0.05) and ROP required treatment (p < 0.05). Pregnancy bleeding was associated with higher superficial foveal vessel density (p < 0.05) and smaller FAZ (p < 0.05). ConclusionNeonatal factors have a huge impact on retinal development, but the role of prenatal factors should not be neglected in preterm children.

Optical coherence tomography angiography of the foveal avascular zone after successful macula‐off rhegmatogenous retinal detachment repair

Aims/Purpose: To investigate the size and shape of the foveal avascular zone (FAZ) after successful macula‐off rhegmatogenous retinal detachment (RRD) repair using swept source OCT angiography (SS OCTA).Methods: A prospective comparative cross‐sectional study including 21 eyes of 21 patients with macula‐off RRD that were successfully repaired. The size of the superficial FAZ was assessed by its area, length of perimeter, and Feret's diameter, and the shape by the circularity, axial ratio, roundness and solidity. The correlations between each parameter and the clinical and OCT findings were statistically determined. The unaffected fellow eyes were used as controls.Results: The mean initial BCVA was 1.92 ± 0.41 Log MAR (20/2000 Snellen's equivalent). The mean BCVA at OCTA acquisition (3 months) was 0.78 ± 0.39 Log MAR (20/100 Snellen's equivalent) (p &lt; 0.001). FAZ was significantly larger (323.09 ± 129.03 μm2 vs. 245.27 ± 93.15 μm2; p = 0.038), with longer perimeter (2.31 ± 0.35 mm vs. 2.07 ± 0.31 mm; p = 0.048), and irregular shaped (mean circularity: 0.73 ± 0.72 vs. 0.78 ± 0.5; p = 0.019 and mean solidity: 0.90 ± 0.02 vs. 0.93 ± 0.02; p = 0.002) in operated eyes than in the control group. The average Feret's diameter was 0.77 ± 0.10 mm versus 0.71 ± 0.88 mm (p = 0.076). The average axial ratio was 1.25 ± 0.20 versus 1.22 ± 0.22 (p = 0.531), and the average roundness was 0.81 ± 0.11 versus 0.83 ± 0.11 (p = 0.531). Mean central foveal thickness (CFT) was significantly lower in operated eyes than in control eyes (178.23 ± 40.59 μm vs. 247.44 ± 38.2 μm (p &lt; 0.001)). There was a significant inverse correlation between FAZ area and post‐operative outer nuclear layer thickness (r = −0.520, p = 0.016) and CFT (r = −0.571, p = 0.007) in operated eyes. There was no significant correlation between the post‐operative visual acuity and FAZ parameters.Conclusions: Enlargement and irregularities of FAZ after successful macula‐off RRD repair, as demonstrated by SS OCTA, might suggest an ischaemic macular damage caused by RRD that may affect post‐operative functional outcome.

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

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. 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. 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. 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.

Retinal mid-peripheral capillary free zones are enlarged in cognitively unimpaired older adults at high risk for Alzheimer’s disease

BackgroundCompared to standard neuro-diagnostic techniques, retinal biomarkers provide a probable low-cost and non-invasive alternative for early Alzheimer’s disease (AD) risk screening. We have previously quantified the periarteriole and perivenule capillary free zones (mid-peripheral CFZs) in cognitively unimpaired (CU) young and older adults as novel metrics of retinal tissue oxygenation. There is a breakdown of the inner retinal blood barrier, pericyte loss, and capillary non-perfusion or dropout in AD leading to potential enlargement of the mid-peripheral CFZs. We hypothesized the mid-peripheral CFZs will be enlarged in CU older adults at high risk for AD compared to low-risk individuals.Methods20 × 20° optical coherence tomography angiography images consisting of 512 b-scans, 512 A-scans per b-scan, 12-µm spacing between b-scans, and 5 frames averaged per each b-scan location of the central fovea and of paired major arterioles and venules with their surrounding capillaries inferior to the fovea of 57 eyes of 37 CU low-risk (mean age: 66 years) and 50 eyes of 38 CU high-risk older adults (mean age: 64 years; p = 0.24) were involved in this study. High-risk participants were defined as having at least one APOE e4 allele and a positive first-degree family history of AD while low-risk participants had neither of the two criteria. All participants had Montreal Cognitive Assessment scores ≥ 26. The mid-peripheral CFZs were computed in MATLAB and compared between the two groups.ResultsThe periarteriole CFZ of the high-risk group (75.8 ± 9.19 µm) was significantly larger than that of the low-risk group (71.3 ± 7.07 µm), p = 0.005, Cohen’s d = 0.55. The perivenule CFZ of the high-risk group (60.4 ± 8.55 µm) was also significantly larger than that of the low-risk group (57.3 ± 6.40 µm), p = 0.034, Cohen’s d = 0.42. There were no significant differences in foveal avascular zone (FAZ) size, FAZ effective diameter, and vessel density between the two groups, all p > 0.05.ConclusionsOur results show larger mid-peripheral CFZs in CU older adults at high risk for AD, with the potential for the periarteriole CFZ to serve as a novel retinal vascular biomarker for early AD risk detection.

Evaluation of retina and choroid perfusion with optical coherence tomography angiography in patients with retinitis pigmentosa

PurposeIn this study, we aimed to evaluate macular perfusion with optical coherence tomography angiography (OCTA) and to investigate the correlation between OCTA quantitative data and visual acuity (VA) in patients with retinitis pigmentosa (RP). MethodsThis retrospective single-center study was conducted on 60 eyes of 30 RP patients and 52 healthy eyes. The vessel density (VD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) of the macula, the size of foveal avascular zone (FAZ), choriocapillary flow density (FD) were measured using OCTA. Quantitative data obtained with OCTA were compared between the two groups. In addition, the correlation between the OCTA measurements and VA was examined. ResultsIn patients with RP, the choriocapillary FD was decreased (p = 0.001), the FAZ area was enlarged (p = 0.010), and the VDs of the SCP and DCP were decreased in all areas (p = 0.001). Correlation was found between VA and SCP VD, whole image (p = 0.011, rho = -0.327) and parafoveal (p = 0.001, rho = -0.444) areas. ConclusionQuantitative data from OCTA showed reduced macular perfusion in patients with RP compared to healthy controls. There was also a correlation between the quantitative OCTA data and VA.

Foveal avascular zone size and mfERG metrics in diabetes and prediabetes: a pilot study of the relationship between structure and function.

Previous studies have demonstrated functional and structural retinal changes in type 2 diabetes (T2DM). However, less is understood in prediabetes, which is an important precursor to T2DM. Here, we evaluate the microvasculature structure of the foveal avascular zone (FAZ) and how it is correlated with retinal function as measured by the multifocal electroretinogram (mfERG) across levels of glucose dysfunction to uncover how T2DM and prediabetes alter this structure-function relationship. 33 subjects were included: 9 controls, 12 prediabetes, 12 T2DM with no retinopathy or edema. Subjects were aged 30-70years, had BCVA of 20/25 or better, and had no confounding ocular conditions. Blood was collected via fingerstick to determine Hemoglobin A1c (HbA1c), which was used along with previous diagnosis, to determine study grouping. Optical coherence tomography angiography (OCTA) was used to analyze the FAZ area and was corrected for refractive error. FAZ area was measured by hand using the Heidelberg Spectralis software. mfERG (VERIS 6.3) metrics implicit time (IT) and amplitude were evaluated in the foveal region, macular region, and averaged over the posterior pole of the right eye. Regression analysis was performed between each study group parameter to determine relationships, and t tests with corrections were used to compare groups. FAZ area (superficial plexus) was negatively correlated with mfERG posterior pole amplitude (p < 0.01, R2 = 0.30), foveal amp (p = 0.02 R2 = 0.17) and macular amplitude (p = 0.02 R2 = 0.18) across all 33 study subjects. FAZ and mfERG metrics were not significantly different between study groups in this cohort except for IT, which was more delayed in the diabetes group compared to other groups. FAZ area is correlated with mfERG amplitudes but not IT. This suggests a link between the structural metrics and retinal function. Longitudinal follow-up work would be helpful to determine the timing of these changes in prediabetes.

The Association of Neovascularization With Optical Coherence Tomography Angiography Parameters in Proliferative Diabetic Retinopathy.

We aim to find an association between neovascularization (NVn) and optical coherence tomography angiography (OCTA) parameters in proliferative diabetic retinopathy (PDR). In a prospective study, 41 subjects including 28 (68%) males and 13 (32%) femaleshaving PDR were examined for neovascularization disc (NVD) and neovascularization elsewhere (NVE) clinically and with fundus fluorescein angiography (FFA). A total of 79 eyes were found to be involved. We examined OCTA parameters including foveal avascular zone (FAZ) size, perimeter and circularity, and vessel density (VD) in the superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retina (OR), outer retinal chorio-capillaries (ORCC), chorio-capillaries (CC), and choroid (C) in these subjects. In eyes with NVD, the central foveal thickness (CFT) (p=0.83) and sub-foveal choroidal thickness (SFCT) (p=0.08) were higher, the FAZ area was significantly larger (p=0.005), and the VD was lower in all retino-choroidal layers. However, it was significantly lower in SCP foveal (p=0.005) and ORCC foveal (p=0.05) than in eyes not having NVD. For NVE, the CFT (p=0.03) and SFCT (p=0.01) were more in affected eyes. The eyes without NVE had a better circularity index (p=0.07) and the highest VD in OR slab (p=0.02) than those eyes that had NVE < ½ disc area (DA) and NVE > ½ DA. On comparing eyes without NVE, NVE < ½ DA, and NVE > ½ DA, the latest had the highest VD in SCP (p=0.59) and lowest VD in DCP (p=0.43) and OR (p=0.02). The VD in ORCC, CC, and choroid was highest in the no NVE group, followed by the NVE > ½ DA and NVE < ½ DA groups in that order. The subjects having vitreous hemorrhage (VH) and intra-retinal microvascular abnormalities (IRMA) had higher values for CFT and SFCT than eyes without these. An increased CFT and SFCT are associated with the appearance of NVD, NVE, VH, and IRMA. The presence of NVD, VH, and IRMA is associated with a larger FAZ area, while that of IRMA and NVE is associated with reduced FAZ circularity. Eyes with NVD, VH, and IRMA had lesser VD in all the retino-choroidal layers. Eyes with NVE > ½ DA had the highest VD in SCP and lowest in DCP and OR; this pattern of VD foretells severer affection in NVE. IRMA was associated with a larger FAZ area, larger FAZ perimeter, and lesser circularity, indicating the presence of central ischemia.

Analysis of Vascular Changes of Fundus in Behcet's Uveitis by Widefield Swept-source Optical Coherence Tomography Angiography and Fundus Fluorescein Angiography.

To investigate vascular changes of fundus in quiescent Behçet's uveitis(BU) based on widefield swept-source optical coherence tomography angiography(SS-OCTA) and fluorescein angiography (FA). This case-control study included 33 quiescent BU patients(57eyes)and 35 healthy people(60 eyes) as the control. All participants underwent the widefield SS-OCTA, and BU patients additionally underwent the FA. The quantitative analysis of the widefield SS-OCTA assessed the vessel density(VD) of 9 anatomic locations in the fundus. Vascular leakage and retinal nonperfusion on FA were assessed in BU patients. Compared with the control group using Mann-Whitney U test, BU patients had enlargement of foveal avascular zone (FAZ) (P=0.005, P=0.04, respectively) and decreased VD within a 300μm width around the FAZ(FAZ300μm) (P=0.001, P<0.0001, respectively) both in the superficial and deep retina. Larger FAZ size and lower FAZ300μm were correlated with higher logarithm of the minimum angle of resolution best-corrected visual acuity in BU (P≤0.003, P<0.0001, respectively). VD of choriocapillaris(CC), as the most widely involved of all layers of the retina and choroid, was lower in 6 locations(P≤ 0.03∼0.0001) in the peripheral fundus of BU compared to the controls. Vascular leakage and retinal nonperfusion in the peripheral fundus was observed in 54.4% and 66.7% of the patients on FA. Fovea and peripheral fundus were prone to the damage of ischemia as evidenced by significantly decreased VD of capillaries. Combination of SS-OCTA with FA could accurately evaluate the changes in the retinal and choroidal vasculature in BU.

Commentary: Optical coherence angiography in intermediate uveitis: What is the scope?

Intermediate uveitis is a subset of uveitis where the vitreous is the primary site of inflammation. It is associated with an infection or systemic disease.[1] The disease affects individuals in all age groups but predominantly affects the third to the fourth decade.[2] In India, the incidence of intermediate uveitis is 1.4/100,000 and its prevalence is 0.25%.[3] Ocular inflammation can cause vascular occlusion, ischemia, capillary leak, and alteration of cellular mediators. Due to the sequalae of uveitis, sight-threatening ocular complications such as macula edema are seen. Early identification, treatment, and monitoring play a crucial role in visual recovery. Regardless of the anatomical location of uveitis, the most common complication of uveitis is macula edema. This is due to the release of inflammatory cytokines that disrupt the inner and outer blood-retina barrier. These changes occur even in anterior uveitis, presumably due to diffusion of inflammatory mediators in the vitreous. Imaging in uveitis is a game changer in the practice patterns of uveitis. Pro-imaging strategies have helped the clinician improvise the quality of eye care and play an important tool in management of ocular inflammation. With the advent of optical coherence tomography angiography (OCTA), an insight into the retinal microvascular changes provides additional information in the pathophysiological changes in uveitis.[4] Based on the definition of intermediate uveitis, the primary site of inflammation is in the vitreous and peripheral retina.[1] Acquiring images of the pars plana, ciliary body, and the peripheral retina is beyond the reach of OCTA. Though there are numerous studies on the microvasculature changes on OCTA in various retinal diseases, little is known about the changes in intermediate uveitis. However, a recent study analyzed the quantitative analyses of macular vascular structures in intermediate uveitis. They demonstrated significantly reduced vascular density in both superficial and deep retinal layers in intermediate uveitis patients [Table 1].[5]Table 1: Studies on OCTA in intermediate uveitisIn a case–control study on intermediate uveitis, reduced vascular density and complexity in superficial as well as deep retinal layers and altered choriocapillaris perfusion were detected. These alterations in OCTA indicates an impairment of the macular microvasculature even in the absence of macular edema.[6] Tian et al.[7] also reported that intermediate uveitis and vasculitis presented with reduced central vessel density. On OCTA, capillary non-perfusion and reduced perfusion was observed more in the choroid, choriocapillaris, and deep capillary plexus than in the superficial capillary plexus. Intermediate uveitis with vasculitis presented more with non-perfusion and hypoperfusion in the deep capillary plexus and superficial capillary plexus than intermediate uveitis without vasculitis. Ischemia on fluorescein angiogram was associated with non-perfusion on wide-field OCTA in superficial and deep capillary plexus. Tian et al.[8] reported another prospective: a cross-sectional study to evaluate vascular changes in patients with intermediate uveitis with or without vasculitis (wide-field montage and central 3 × 3 mm slabs). Though the wide-field images gave important information about peripheral vascular changes, their lower resolution limited the detectability of flow alterations compared to the high resolution of the central scans. Microvascular changes in eyes with intermediate uveitis were found at the level of the superficial capillary plexus, deep capillary plexus, the choriocapillaris, and the choroid. Also, a change of central vascular density found in the central scans did not correlate to alterations found on wide-field OCTA. They also concluded that rather than the presence of an epiretinal membrane and a macula edema, intermediate uveitis had an alteration on the foveal avascular zone size. Capillary changes may be also found beyond the posterior pole on wide-field OCTA. The differences in capillary density and morphology that was detected in uveitis patients shows that the effects of intraocular inflammation can be quantitatively measured even within a 3 × 3 mm2 parafoveal window.[8] Along with investigating the gross changes in the peripheral retina with wide-field imaging studies, OCTA assessment of changes in the parafoveal capillary density and branching complexity provides a unique assessment of disease severity that is not otherwise available. Surprisingly, not only the retinal vasculature is altered but also the choriocapillaris and the choroid is affected in intermediate uveitis. This definitely indicates that long-term studies on this domain are needed. Data on active eyes with intermediate uveitis are sparse. Hence, we would need to evaluate the disease activity which can be visualized using OCTA.

STELLATE NONHEREDITARY IDIOPATHIC FOVEOMACULAR RETINOSCHISIS: NOVEL FINDINGS AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ANALYSIS.

To present novel findings in stellate nonhereditary idiopathic foveomacular retinoschisis, including the largest series of optical coherence tomography angiography findings to date. A retrospective case series with multimodal imaging was obtained and reviewed. All three patients were women, aged 59-63. Two cases were unilateral, and one was bilateral. Vision ranged from 20/20 to 20/60 in the affected eyes. Peripheral retinoschisis was observed in all three patients. All patients were followed for a minimum of 1 year. In one case, progressive macular retinoschisis leading to foveal involvement was observed over two years, with an associated vision decline from 20/25 to 20/60. Attempted interventions included topical dorzolamide in all cases and intravitreal bevacizumab in one patient; however, no treatment effect was observed. The foveal avascular zone size was within normal limits (mean 280 µ m). In all stellate nonhereditary idiopathic foveomacular retinoschisis eyes, the retinoschisis cavities were nonvascular. Novel findings regarding stellate nonhereditary idiopathic foveomacular retinoschisis include the progressive nature of foveal involvement and the lack of response to topical dorzolamide and intravitreal bevacizumab. Foveal avascular zone was normal in all eyes, consistent with the relatively preserved vision in these cases. Retinoschisis cavities were nonvascular in all eyes, a finding which may give insight into the mechanism of this disease.

Microvasculature evaluation of anisometropic amblyopia children by Angio-OCT

To compare and assess the choroidal and retinal microstructural vascularity in amblyopic eyes with the fellow eyes in anisometropic amblyopic children using angiography optical coherence tomography (Angio-OCT). Twenty-seven children (54 eyes; 5.59 ± 1.08 years old; 59.3% girls) were enrolled in this study. Choroidal thickness (CT) was measured with the use of the enhanced depth imaging mode in Angio-OCT. Parafoveal/peripapillary vascular density indices and the foveal avascular zone (FAZ) size were analyzed by MATLAB code programming on Angio-OCT images. The mean FAZ size of the amblyopic eyes were larger both in superficial and deep capillary plexus layer (SCPL/DCPL). Compared with the contralateral eyes (BCVA were normal), all the vascular density indices of SCPL and DCPL in the parafoveal and peripapillary zones were lower in the amblyopic eyes, however, the difference was insignificant (p > 0.05). No significant decrease was observed in four quadrants analyses of the amblyopic eyes (p > 0.05). Except for the measurement at 2000 µm and 1500 µm from the fovea in temple, CT in amblyopic eyes were significantly thicken than the fellow eyes (p < 0.05). Compared with the fellow eyes, the CT of certain areas were thicker in the amblyopic eyes. Though the FAZ size of the amblyopic eyes was larger in SCPL/DCPL layers, the retinal vascular density indices in SCPL/DCPL were lower in amblyopia eyes without statistical difference. Angio-OCT may be an effective way to evaluate the status of the choroidal and retinal vascular system in amblyopic children.

Macular vascularisation changes analysed using OCT angiography after successful rhegmatogenous retinal detachment repair.

To analyse the macular vascularisation changes analysed using optical coherence tomography angiography (OCTA) after successful rhegmatogenous retinal detachment (RRD) repair by comparing gas vs silicone oil and macula-on vs macula-off. This retrospective data collection included 77 eyes with RRD that underwent pars plana vitrectomy (PPV) and gas or silicone oil tamponade. We performed an OCTA during the postoperative control between 6 and 24mo after the last surgery and evaluated the main parameters measured by OCTA: foveal avascular zone (FAZ) and parafoveolar vascular density (PVD) in the superficial capillary plexus. The patients were divided into four groups: RRD with macular involvement treated with gas tamponade, RRD without macular involvement treated with gas tamponade, RRD with macular involvement treated with silicone oil tamponade and RRD without macular involvement treated with silicone oil tamponade. A one-way ANOVA test combined with post hoc Bonferroni corrections compared FAZ sizes and PVD in all four groups. The FAZ size was statistically significantly larger in eyes with RRD involving the macula than in those not involving it (P=0.005). There was no statistically significant difference in the FAZ sizes of the eyes treated with silicone oil tamponade compared to those treated with gas tamponade (P=0.54). There was no statistically significant difference in the PVD comparing all four groups. Despite the known risks associated with silicone oil, our findings suggest that the type of tamponade used during PPV to treat an RRD has no significant effect on the future integrity of the PVD or the size of the FAZ in the superficial capillary plexus as measured by OCTA.

An Open-source Image Analysis Toolbox for Quantitative Retinal Optical Coherence Tomography Angiography.

Qualitative and quantitative assessment of retinal perfusion using optical coherence tomography angiography (OCTA) has shown to be effective in the treatment and management of various retinal and optic nerve diseases. However, manual analyses of OCTA images to calculate metrics related to Foveal Avascular Zone (FAZ) morphology, and retinal vascular density and morphology are costly, time-consuming, subject to human error, and are exposed to both inter and intra operator variability. This study aimed to develop an open-source software framework for quantitative OCTA (QOCTA). Particularly, for analyzing OCTA images and measuring several indices describing microvascular morphology, vessel morphology, and FAZ morphology. In this analytical study, we developed a toolbox or QOCTA using image processing algorithms provided in MATLAB. The software automatically determines FAZ and measures several parameters related to both size and shape of FAZ including area, perimeter, Feret's diameter circularity, axial ratio, roundness, and solidity. The microvascular structure is derived from the processed image to estimate the vessel density (VD). To assess the reliability of the software, three independent operators measured the mentioned parameters for the eyes of 21 subjects. The consistency of the values was assessed using the intraclass correlation coefficient (ICC) index. Excellent consistency was observed between the measurements completed for the superficial layer, ICC >0.9. For the deep layer, good reliability in the measurements was achieved, ICC >0.7. The developed software is reliable; hence, it can facilitate quantitative OCTA, further statistical comparison in cohort OCTA studies, and can assist with obtaining deeper insights into retinal variations in various populations.

The early diagnostic value of optical coherence tomography (OCT) and OCT angiography in thyroid-associated ophthalmopathy.

The retinal microvascular density changes have been identified in thyroid-associated ophthalmopathy (TAO) patients. Whereas a lack of research has been done on the diagnostic ability of optical coherence tomography (OCT) combined with optical coherence tomography angiography (OCTA) parameters. This study aims to evaluate the retina perfusion variations in eyes with active and stable TAO and its diagnostic abilities using OCT and OCTA. This is cohort longitudinal retrospective study. A total of 51 patients with TAO and 39 healthy controls (HCs) were recruited. The TAO eyes were divided into active and stable stage groups. The foveal avascular zone (FAZ), macular perfusion density (mPD), and peripapillary PD were measured by OCTA. The peripapillary retinal nerve fiber layer (RNFL), central retinal thickness (CRT), and whole macular volume (wMV) were measured by OCT. Visual evoked potential (VEP) and visual field (VF) were also assessed. The mPD of the superficial retinal capillary plexus (SRCP) was significantly different in all subfields among active, stable, and HC groups (p < 0.05) except for the temporal inner (p = 0.137), and the active group achieved the lowest PD. The FAZ size increased significantly in the active and stable groups compared with the HC group (p < 0.001). Significant difference was observed in mPD of deep retinal capillary plexus (DRCP) in all quadrants among three groups (p < 0.05). Moreover, PD parameters of optic nerve head (ONH) and radial peripapillary capillary plexus (RPCP) showed a different trend among three groups (p < 0.05). The r-value of visual field-mean deviation (VF-MD) of TAO with DRCP-whole PD (wPD) and RPCP-wPD was 0.421 and 0.299, respectively (p < 0.05). The DRCP-wPD in OCTA and RNFL in OCT were significantly higher in area under the receiver operating characteristic curve (AUC) than that of HC eyes. OCT and OCTA can noninvasively detect the peripapillary and macular changes in various stages of TAO patients, and it might be a high diagnostic value tool to monitor the TAO progression.