Macula Vessel Density and Foveal Avascular Zone Parameters in Exfoliation Glaucoma Compared to Primary Open-Angle Glaucoma

The Effect of Latanoprostene Bunod 0.024% on Optical Coherence Tomography Angiography in Newly Diagnosed Open Angle Glaucoma

PRCIS

Treatment with LBN ophthalmic solution 0.024% reduced IOP by an average of 29.9% and 31.8% in patients with POAG and PXG, respectively, and improved VD in different quadrants in all slabs. Therefore, the importance of LBN in the treatment of glaucoma is likely to be that it increases macular microcirculation, possibly through NO, independent of its IOP-reducing effect.

PURPOSE

The aim of this study was to investigate the effect of topical latanoprostene bunod 0.024% applied once daily on intraocular pressure and macular vessel density in newly diagnosed primary and pseudoexfoliative open angle glaucoma patients.

METHODS

A total of 66 patients with newly diagnosed open angle glaucoma were included in this study (group 1). Thirty-four patients had primary (POAG, group 1A) and 32 patients had secondary (pseudoexfoliative glaucoma, PXG, group 1B) open angle glaucoma. Thirty-two healthy participants (group 2) were included in this single-center, prospective study.

RESULTS

In group 1, the mean IOP decrease in first month of treatment with LBN was 7.7 mm  Hg and IOP change was -30.8%. In the superficial slab, the vessel density (VD) in the superior and nasal quadrants was lower in group 1B compared with group 1A in the first month of treatment ( P =0.038, 0.019, respectively). In the choriocapillaris slab, the VD in the superior quadrant at baseline (before treatment) was statistically lower in both groups compared with the VD in the superior quadrant in the first month of treatment ( P <0.001, for both).

CONCLUSION

In conclusion, treatment with LBN ophthalmic solution 0.024% reduced IOP by an average of 29.9% and 31.8% in patients with POAG and PXG, respectively, and improved VD in different quadrants in all slabs. Therefore, the importance of LBN in the treatment of glaucoma is likely to be that it increases macular microcirculation, possibly through NO, independent of its IOP-reducing effect.

Comparing structural and vascular parameters between advanced pseudoexfoliation glaucoma and primary open angle glaucoma using optical coherence tomography angiography

BACKGROUND

To compare structural and vascular parameters between advanced pseudoexfoliation glaucoma (PXG) and primary open-angle glaucoma (POAG).

METHODS

One hundred and six eyes of 81 patients were enrolled in this cross-sectional study. All patients underwent complete ophthalmic examination and measurement of the thickness of the peripapillary retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). The vessel densities (VD) in the peripapillary and macular area were also determined using optical coherence tomography angiography (OCTA). A linear mixed model was used for the comparison of the structural and vascular parameters between groups with adjustment for type of glaucoma, age, sex, intraocular pressure (IOP), and mean deviation (MD) of the visual field C24-2.

RESULTS

The patients in the PXG group were significantly older (68.06 ± 10.6 vs. 61.24 ± 15.23, p = 0.01) and had worse MD in the visual field C24-2 (-24.83 ± 6.18 vs. -22.37 ± 5.94, p = 0.04). Sex and IOP were comparable between groups (p > 0.05). Perippaillry RNFL and GCC thickness were not different between groups (p > 0.05). The PXG eyes showed lower VD in the average peripapillary area (32.67 ± 7.78 vs. 37.75 ± 8.87, p = 0.027) and nasal (37.45 ± 9.74 vs. 42.15 ± 7.36, p = 0.026) and inferior (38.09 ± 8.27 vs. 42.71 ± 9.13, p = 0.041) quadrants of parafovea.

CONCLUSION

The advanced PXG and POAG eyes have comparable structural defects in the peripapillary and inner macula while the PXG eyes may have more vascular deterioration, especially in the macula.

Applications of optical coherence tomography angiography in glaucoma: current status and future directions

Glaucoma is a leading cause of irreversible blindness worldwide, with its pathophysiology remaining inadequately understood. Among the various proposed theories, the vascular theory, suggesting a crucial role of retinal vasculature deterioration in glaucoma onset and progression, has gained significant attention. Traditional imaging techniques, such as fundus fluorescein angiography, are limited by their invasive nature, time consumption, and qualitative output, which restrict their efficacy in detailed retinal vessel examination. Optical coherence tomography angiography (OCTA) emerges as a revolutionary imaging modality, offering non-invasive, detailed visualization of the retinal and optic nerve head microvasculature, thereby marking a significant advancement in glaucoma diagnostics and management. Since its introduction, OCTA has been extensively utilized for retinal vasculature imaging, underscoring its potential to enhance our understanding of glaucoma's pathophysiology, improving diagnosis, and monitoring disease progression. This review aims to summarize the current knowledge regarding the role of OCTA in glaucoma, particularly its potential applications in diagnosing, monitoring, and understanding the pathophysiology of the disease. Parameters pertinent to glaucoma will be elucidated to illustrate the utility of OCTA as a tool to guide glaucoma management.

The Role of Optical Coherence Tomography Angiography in Glaucoma

Glaucoma is the leading cause of irreversible vision loss and comprises a group of chronic optic neuropathies characterized by progressive retinal ganglion cell (RGC) loss. Various etiologies, including impaired blood supply to the optic nerve, have been implicated for glaucoma pathogenesis. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality for visualizing the ophthalmic microvasculature. Using blood flow as an intrinsic contrast agent, it distinguishes blood vessels from the surrounding tissue. Vessel density (VD) is mainly used as a metric for quantifying the ophthalmic microvasculature. The key anatomic regions for OCTA in glaucoma are the optic nerve head area including the peripapillary region, and the macular region. Specifically, VD of the superficial peripapillary and superficial macular microvasculature is reduced in glaucoma patients compared to unaffected subjects, and VD correlates with functional deficits measured by visual field (VF). This renders OCTA similar in diagnostic capabilities compared to structural retinal nerve fiber layer (RNFL) thickness measurements, especially in early glaucoma. Furthermore, in cases where RNFL thickness measurements are limited due to artifact or floor effect, OCTA technology can be used to evaluate and monitor glaucoma, such as in eyes with high myopia and eyes with advanced glaucoma. However, the clinical utility of OCTA in glaucoma management is limited due to the prevalence of imaging artifacts. Overall, OCTA can play a complementary role in structural OCT imaging and VF testing to aid in the diagnosis and monitoring of glaucoma.

Macula vessel density and its relationship with the central visual field mean sensitivity across different stages of exfoliation glaucoma

CLINICAL RELEVANCE

Alterations in ocular microvasculature may contribute to pathogenesis of exfoliation glaucoma (XFG) and may improve monitoring this aggressive type of open angle glaucoma.

BACKGROUND

This work aims to compare the macula vessel density and the relationship between macula vessel density and central visual field mean sensitivity between eyes with XFG and eyes with primary open-angle glaucoma (POAG) of different stages.

METHODS

In this cross-sectional observational study, the macula vessel density values were compared among 52 POAG cases (26 early stage, 26 moderate to advanced stage) and 53 XFG cases (27 early stage, 26 moderate to advanced stage). The vessel density values were evaluated with optical coherence tomography angiography. Vasculature-function and structure-function relationships were analysed by comparing macula vessel density, inner macula thickness and visual field mean sensitivity in early and moderate to advanced stages of XFG and POAG eyes separately.

RESULTS

The early stage XFG eyes had a significantly lower global macula vessel density compared with early stage POAG eyes (42.81 ± 3.85% and 46.56 ± 3.90%, respectively; p = 0.02). However, the tendency of XFG eyes for a lower vessel density compared with the POAG eyes did not exhibit any significance in moderate to advanced stages of glaucoma (37.39 ± 5.65% and 38.35 ± 4.67%, respectively; p = 0.9). The macula vessel density (%)-visual field mean sensitivity (1/Lambert) correlation was statistically significant in early stage XFG eyes (r = 0.464 p = 0.01), while no such correlation was notable for the early stage POAG eyes (r = -0.029 p = 0.89).

CONCLUSION

The macula vessel density appears to be more severely affected in early stage XFG than POAG of similar severity, suggesting a relatively greater value of vascular insufficiency in XFG. The significant vasculature-function association in early stage XFG, which was absent in early stage POAG, may infer the importance of macula vessel density in monitoring functional loss in early stages of XFG.

Enhancing foveal avascular zone analysis for Alzheimer's diagnosis with AI segmentation and machine learning using multiple radiomic features

We propose a hybrid technique that employs artificial intelligence (AI)-based segmentation and machine learning classification using multiple features extracted from the foveal avascular zone (FAZ)-a retinal biomarker for Alzheimer's disease-to improve the disease diagnostic performance. Imaging data of optical coherence tomography angiography from 37 patients with Alzheimer's disease and 48 healthy controls were investigated. The presence or absence of brain amyloids was confirmed using amyloid positron emission tomography. In the superficial capillary plexus of the angiography scans, the FAZ was automatically segmented using an AI method to extract multiple biomarkers (area, solidity, compactness, roundness, and eccentricity), which were paired with clinical data (age and sex) as common correction variables. We used a light-gradient boosting machine (a light-gradient boosting machine is a machine learning algorithm based on trees utilizing gradient boosting) to diagnose Alzheimer's disease by integrating the corresponding multiple radiomic biomarkers. Fivefold cross-validation was applied for analysis, and the diagnostic performance for Alzheimer's disease was determined by the area under the curve. The proposed hybrid technique achieved an area under the curve of [Formula: see text]%, outperforming the existing single-feature (area) criteria by over 13%. Furthermore, in the holdout test set, the proposed technique exhibited a 14% improvement compared to single features, achieving an area under the curve of 72.0± 4.8%. Based on these facts, we have demonstrated the effectiveness of our technology in achieving significant performance improvements in FAZ-based Alzheimer's diagnosis research through the use of multiple radiomic biomarkers (area, solidity, compactness, roundness, and eccentricity).

Comparison of microvascular parameters and diagnostic ability of optical coherence tomography angiography between eyes with primary angle closure glaucoma and primary open angle glaucoma

BACKGROUND

To investigate and compare the peripapillary and macular microvascular parameters between eyes with primary angle closure glaucoma (PACG) and primary open-angle glaucoma (POAG) using optical coherence tomography angiography (OCTA).

METHODS

Seventy-nine eyes of 43 patients with primary angle closure glaucoma (PACG), 78 eyes of 43 patients with primary open-angle glaucoma (POAG), 64 eyes of 35 patients with primary angle closure (PAC), and 73 eyes of 40 control subjects underwent imaging with OCTA. Perfusion density (PD) and vessel density (VD) for the macular area, and PD and flux index (FI) for the peripapillary area were calculated automatically. The area under receiver operator characteristic curves (AUC) were constructed to distinguish PACG and POAG eyes from healthy control eyes.

RESULTS

The peripapillary FI in all quadrants and PD and VD of the macular outer circle in superior and inferior quadrants were significantly lower in PACG and POAG eyes than in control eyes. The peripapillary FI in the inferior quadrant was significantly lower in the POAG group than in the PACG group (0.348 ± 0.06 vs. 0.369 ± 0.06, p = 0.04). The remaining OCTA parameters in the peripapillary and macular area did not show a significant difference between the POAG and PACG groups. Eyes with PAC presented significantly lower PD and VD than healthy control eyes at the superior and inferior quadrant of the macular outer circle, while retinal nerve fiber layer and ganglion cell inner complex thickness were not significantly different from than control eyes. The best diagnostic parameter was peripapillary FI in both PACG (AUC: 0.922) and POAG (AUC: 0.938) eyes.

CONCLUSIONS

We found significantly lower peripapillary FI in the inferior quadrant in POAG eyes compared to the PACG eyes, which may indicate the different underlying pathogenesis between POAG and PACG. The PAC eyes had lower macular PD and VD than normal eyes. This suggests that retinal vascular impairment may develop earlier than structural damage in PAC eyes.

Peripapillary and fovea avascular zone optical coherence tomography angiography parameters in exfoliation glaucoma versus primary open-angle glaucoma versus healthy eyes

Purpose

To examine the differences in the peripapillary vascular parameters and foveal-avascular-zone (FAZ) vascularity parameters between primary open-angle-glaucoma (POAG) patients versus exfoliation-glaucoma (XFG) patients versus healthy subjects.

Methods

This is cross-sectional study and a comparative clinical study. POAG and XFG patients and healthy subjects underwent a comprehensive ophthalmic examination, including visual field optical coherence tomography (OCT) and OCT angiography (OCTA) of the optic disc and FAZ. Differences in peripapillary vessel density (VD), perfusion density (PD), and FAZ area and circularity were examined between all groups, as well as correlations between clinical parameters and vascularity parameters for each glaucoma group.

Results

A total of 109 subjects (one eye for each patient) were analyzed, including 45 with POAG, 30 with XFG, and 34 controls. The average peripapillary VDs were the lowest among the XFG patients and the highest among the controls (P < 0.05, ANOVA). The average peripapillary PD of the central ring was the lowest in the XFG group and the highest in the control group (P = 0.02, ANOVA). A significant negative correlation was found between the average peripapillary VDs and PDs of the inner ring and full ring and disease severity of the POAG patients. There was a significant positive correlation between the average peripapillary PDs of the central rings and full ring and the central macular thickness of the XFG patients (P < 0.01 and P < 0.04, respectively, Pearson correlation).

Conclusion

The peripapillary vascular parameters of the POAG and XFG patients were lower compared to those of normal participants. A correlation between clinical characteristics of POAG and XFG patients and PD was found. This may hint to a vascular mechanism in glaucoma either primary or secondary to intra-ocular pressure/OAG damage.

The Role of Vessel Density as Measured by Optical Coherence Tomography Angiography in the Evaluation of Pseudoexfoliative Glaucoma: A Review of the Literature

INTRODUCTION

To review the existing literature about the optical coherence tomography angiography (OCTA) findings regarding peripapillary and macular vessel density (VD) in patients with pseudoexfoliative glaucoma (PXG).

METHODS

A comprehensive search of the PubMed database was conducted to include articles up to November 1, 2021, using an appropriate search algorithm. The retrieved articles were assessed for eligibility and filtered manually to exclude duplicates, while articles and book chapters cited in the reference lists of the eligible articles obtained by this method were reviewed so as not to miss any relevant studies.

RESULTS

There is consistency among the studies published so far that a significant decrease in peripapillary VD exists in eyes with PXG compared to controls, and macular VD has also been reported to be significantly lower in PXG eyes than controls. However, the existing literature remains controversial regarding OCTA findings in eyes with PXG compared to those with primary open-angle glaucoma (POAG). Several studies have found that peripapillary VD and macular VD were significantly lower in PXG than POAG, while other studies reported no significant difference.

CONCLUSIONS

Eyes with PXG were found to present decreased peripapillary and macular VD compared to control eyes, suggesting that a vascular component, including optic nerve hypoperfusion, may be implicated in the pathogenesis of PXG.

Measuring optic nerve head perfusion to monitor glaucoma: a study on structure-function relationships using laser speckle flowgraphy

PURPOSE

We aimed to describe the global and localized correlations among visual field (VF) sensitivity, optic nerve head (ONH) perfusion measured by laser speckle flowgraphy (LSFG) and neural structure measured by optical coherence tomography (OCT) in open-angle glaucoma (OAG) and to compare the floor effect for LSFG and OCT.

METHODS

Cross-sectional, multicenter study including one eye each from fifty OAG patients (mean age 69.3 years; average VF mean deviation, MD, -8.5 dB, range -25.17 to 0.85 dB) and fifty-one controls. Patients underwent SITA standard 24-2 automated perimetry and measurement of ONH perfusion, peripapillary retinal nerve fibre layer thickness (RNFLT) and macular ganglion cell-inner plexiform layer thickness (GCIPLT). We tested the presence of a significant change (breakpoint) in the correlation slope with VF sensitivity to assess floor effect.

RESULTS

The correlation between the LSFG parameter Mean All (MA) of the global disc area and MD (r = 0.56, p < 0.001) did not show a breakpoint, in contrast to the correlations between MD and OCT global parameters, which showed breakpoints at -8.53 and -4.05 dB for RNFLT and GCIPLT, respectively. Global and localized correlations with VF sensitivity were stronger for LSFG compared to OCT. In particular, LSFG outperformed OCT in the correlation with the central VF sector (r = 0.50, p < 0.001 and r = 0.06, p = 0.67 for MA and RNFLT, respectively).

CONCLUSION

The global and sectoral correlations with VF sensitivity and the favourable floor effect compared to OCT indicate LSFG as a promising tool to monitor progression particularly in late-stage glaucoma. Further longitudinal studies are warranted.

Comparison of peripapillary and macular vascular density in primary open-angle glaucoma, pseudoexfoliation glaucoma, and normal control eyes

PURPOSE

To compare the optical coherence tomography angiography (OCT-A) of the macula, and optic disc in primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and normal eyes.

METHODS

In this observational, cross-sectional study, Sixty-five eyes with POAG, 61 eyes of age, and mean deviation (MD) from standard automated perimetry matched PXG patients, and 45 normal control eyes underwent OCT-A using AngioVue, and optic disc-associated vessel density (VD), macular-associated VD, Foveal avascular zone (FAZ) area, FAZ perimeter (PERIM), and vessel density within a 300 μm wide region of the FAZ (FD) were compared between groups.

RESULTS

Peripapillary OCT-A parameters were significantly different among normal, and glaucomatous eyes with the highest values in the control eyes, but none of the peripapillary OCT-A parameters except inside disc VD was statistically significantly different between the PXG eyes, and POAG eyes. Correlation analysis revealed significant correlation between mean retinal nerve fiber layer (RNFL) and peripapillary VD in control (r=0.427, P=0.006), PXG (r=0.82, P<0.001), and POAG (r=0.79, P<0.001) eyes. PXG eyes exhibited significantly lower superficial, and deep macular vessel densities in parafoveal and perifoveal regions compared with POAG eyes after adjustment (p<= 0.05). Overall, moderate /severe PXG eyes had lower superficial, and deep vessel densities in parafoveal and perifoveal regions compared to mild PXG.

CONCLUSION

Peripapillary VD (inside disc), and macular vessel densities (parafovea and perifovea) demonstrate a significant difference in age and glaucoma severity-matched POAG and PXG eyes. Moderate/advance glaucomatous eyes, exhibit significant damage to the superficial and deep macular vascular structures.

Optical Coherence Tomography and Glaucoma

Early detection and monitoring are critical to the diagnosis and management of glaucoma, a progressive optic neuropathy that causes irreversible blindness. Optical coherence tomography (OCT) has become a commonly utilized imaging modality that aids in the detection and monitoring of structural glaucomatous damage. Since its inception in 1991, OCT has progressed through multiple iterations, from time-domain OCT, to spectral-domain OCT, to swept-source OCT, all of which have progressively improved the resolution and speed of scans. Even newer technological advancements and OCT applications, such as adaptive optics, visible-light OCT, and OCT-angiography, have enriched the use of OCT in the evaluation of glaucoma. This article reviews current commercial and state-of-the-art OCT technologies and analytic techniques in the context of their utility for glaucoma diagnosis and management, as well as promising future directions.

Macular, papillary and peripapillary perfusion densities measured with optical coherence tomography angiography in primary open angle glaucoma and pseudoexfoliation glaucoma

Purpose

To compare the blood flow situation in primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) using optical coherence tomography angiography (OCTA).

Methods

In this prospective study a total of 26 POAG and 23 PXG eyes were included. All patients underwent a complete ophthalmological examination including standard automated perimetry, stereoscopic photographs of the optic disc, peripapillary retinal nerve fibre layer analysis and examination of vascular parameters of the optic nerve head (ONH), the peripapillary region and macula using OCTA. In addition to the vascular parameters recorded by the device, the vascular images were graphically evaluated using Image J. All recorded vascular parameters were compared between both groups and correlated to structural and functional parameters.

Results

The mean superficial perifoveal plexus perfusion density (PD) was significantly lower in PXG eyes than compared to POAG eyes using OCTA (32.57% ± 3.57% vs. 34.92% ± 2.11%, p = 0.007). The mean PD parameters for the superficial peripapillary plexus (40.98% ± 3.04% vs. 42.09% ± 2.29%, p = 0.152) as well as the size of the foveal avascular zone (FAZ) (0.23 mm² ± 0.1 mm² vs. 0.23 mm² ± 0.09 mm²) did not differ between both groups. Additional graphic evaluation using Image J showed no significant difference for superficial perifoveal plexus PD (32.97% ± 1.11% vs. 33.35% ± 0.95%, p = 0.194) and peripapillary plexus PD (46.65% ± 0.83% vs. 46.95% ± 0.5%, p = 0.127) between the groups. Retinal nerve fibre layer (RNFL) thickness correlated significantly with peripapillary plexus PD for both OCTA data and Image J data (p < 0.001, p = 0.032).

Conclusion

The severity of the glaucoma seems to be crucial for peripapillary and macular perfusion densities, and not the form of glaucoma. An additional graphic evaluation is a possible step that could be implemented to improve the comparability of OCTA scans and to optimize the possibility of quantitative perfusion analysis in the case of deviating quality criteria.

Cut-Off Values of Foveal Vascular Indices in Exfoliation Glaucoma

PURPOSE

To compare the vascular measurements obtained from fovea including foveal avascular zone (FAZ) with optical coherence tomography angiography (OCTA) between patients with exfoliation glaucoma (XFG) and healthy controls.

METHODS

This cross-sectional comparative study included 54 XFG patients and 94 healthy subjects. All subjects were given a complete ophthalmological examination including visual field testing, retinal nerve fiber layer and macular ganglion cell complex analysis. OCTA was performed to evaluate the vascular features of fovea including FAZ. The measurements of vessel density (VD), perfusion density (PD) and FAZ values were segmented and calculated using the inbuilt software on OCTA. Receiver operating characteristic (ROC) analyses were performed to determine the best cut-off values to detect the disease.

RESULTS

In the XFG group, decreased VD, PD and FAZ values were observed. ROC analysis showed an obvious separation, differentiating the patients with XFG from the healthy controls at cut-off value of 19.55 with a sensitivity (sen) of 92.3% and a specificity (spe) of 81.9%) for VD total and 21.20 (sen:100 and spe:78.7) for VD parafoveal; 0.36 (sen:98.1and spe:76.6) for PDtotal and 0.378 (sen:96.2and spe:84) for PDparafoveal; 0.635 (sen: 79.3 and spe:72) for FAZ circulatory index.

CONCLUSION

The results support the findings of decreased microvascular density on foveal region in XFG. The cut off values of the changes in the foveal parameters in patients with exfoliation may be useful in evaluation of future glaucoma management to show how far a particular exfoliative eye is positioned from an healthy eye and how close to XFG.

Peripapillary perfused capillary density in true versus pseudoexfoliation syndrome: An OCTA study

PURPOSE

To compare peripapillary perfused capillary density (PCD) among eyes with true exfoliation syndrome (TEX), eyes with pseudoexfoliation syndrome (PEX), and healthy control eyes.

MATERIALS AND METHODS

In this observational cross-sectional study, eyes with and without TEX or PEX were assessed by optical coherence tomography angiography (OCTA) imaging. Bilateral OCTA images (4.5 × 4.5 mm2) centered at the optic nerve head were obtained using a commercial spectral domain OCTA system. Optic nerve head perfusion was quantified using the split-spectrum amplitude decorrelation angiography algorithm. Categorical and continuous variables were compared using the chi-squared test and one-way analysis of variance, respectively. The generalized estimating equation was used to adjust for confounding factors and determine inter-ocular associations.

RESULTS

We enrolled 39 eyes with TEX, 31 eyes with PEX, and 32 control eyes. There were no significant differences among the three groups regarding age, intraocular pressure, cup-to-disc ratio, blood pressure, or axial length (all p>0.05). There were significant differences in global PCD among the three groups (p = 0.01). There were significant differences in annular PCD between the TEX and PEX groups (p = 0.027).

CONCLUSIONS

While both global and annular PCDs did not differ between the TEX and control groups, greater loss of annular PCD in the PEX group than in the TEX and control groups suggests more pronounced microvascular disturbance in PEX.

SYNOPSIS/PRECIS

Greater microvascular attenuation in PEX compared with TEX and normal control measured by OCTA.

Macular vessel density and foveal avascular zone parameters in patients after acute primary angle closure determined by OCT angiography

This study analyzed the optical coherence tomography angiography (OCTA) macular parameters in primary angle-closure glaucoma (PACG) patients after acute primary angle closure (APAC) episodes. Thirty-three patients with 33 APAC eyes and 33 primary angle closure suspect (PACS) eyes and 33 age-matched normal subjects (controls) were enrolled. Macular vessel density (VD) in central, inner, outer and full regions and foveal avascular zone (FAZ) parameters (area, perimeter and circularity index) were compared between APAC, PACS, and control eyes. For resolved APAC eyes, the VD in each macular region was significantly lower than that in control eyes, with less central and inner macular VD than PACS eyes. The central macular VD was significantly lower in PACS eyes than in controls. There was no difference in FAZ area and perimeter between APAC, PACS, and control eyes. FAZ circularity was highest in control eyes, followed by PACS eyes, and lowest in APAC eyes. The AUC, sensitivity and specificity of FAZ circularity were 0.944, 93.9% and 84.8%, respectively, in APAC eyes and 0.881, 84.8% and 81.8%, respectively, in PACS eyes. Therefore, FAZ circularity had the best discrimination capability for detecting both APAC and PACS eyes. Macular assessment with OCTA could provide an accurate early-stage diagnostic tool for PACG.

Peripapillary and Macular Vessel Density Measurement by Optical Coherence Tomography Angiography in Pseudoexfoliation and Primary Open-angle Glaucoma

PRECIS

Pseudoexfoliation glaucoma eyes had a similar level of peripapillary and superficial macular vessel densities compared with primary open-angle glaucoma eyes matched for age and glaucoma severity when assessed by optical coherence tomography angiography (OCT-A).

PURPOSE

To compare vessel density (VD) measured by OCT-A between primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) in the peripapillary and macular areas.

MATERIALS AND METHODS

The circumpapillary (cpVD), parafoveal (pfVD), and perifoveal vessel densities (perifVD) were obtained using OCT-A (AngioVue/RTVue-XR) in 98 eyes from 98 subjects [age, visual acuity, visual field (VF) mean deviation (MD) matched 49 POAG and 49 PXG eyes]. Global and 8 sectoral VDs in the peripapillary capillary layer were compared. In the macula, the superficial and deep layers of the pfVD and perifVD were analyzed globally and in 4 quadrants. Univariate and multivariate linear regression models were built using cpVD, pfVD, and perifVD as dependent variables and covariates [age, intraocular pressure (IOP), axial length, signal strength index (SSI), and retinal nerve fiber layer (RNFL) thickness] were considered independent variables.

RESULTS

In the peripapillary region, none of the VDs differed between groups both before and after adjustment. When we adjusted superficial and deep layer macular VDs for age, IOP, SSI, axial length, and RNFL thickness, all of which could affect measurements, the 2 groups did not differ in any sector. The cpVD in POAG eyes significantly correlated with VF MD and RNFL thickness, whereas IOP, VF MD, and RNFL thickness affected cpVD in PXG. The macular VD in the deep layer was associated with only SSI in both groups.

CONCLUSIONS

Age-matched and glaucoma severity-matched PXG and POAG did not significantly differ in cpVD or in most of the superficial macular VD parameters.

Optical Coherence Tomography Angiography in Glaucoma

Optical coherence tomography angiography (OCTA) is a relatively new, noninvasive, dye-free imaging modality that provides a qualitative and quantitative assessment of the vasculature in the retina and optic nerve head. OCTA also enables visualization of the choriocapillaris, but only in areas of parapapillary atrophy. With OCTA, the movement of red blood cells is used as a contrast to delineate blood vessels from static tissues. The features seen with OCTA in eyes with glaucoma are reduction in the superficial vessel density in the peripapillary and macular areas, and complete loss of choriocapillaris in localized regions of parapapillary atrophy (called deep-layer microvascular dropout). These OCTA changes correlate well topographically with the functional changes seen on visual field examination and structural changes seen on optical coherence tomography (OCT) (ie, parapapillary retinal nerve fiber layer changes and inner retinal layer thickness changes at macula). The OCTA measurements also have acceptable test-retest variability and well differentiate glaucomatous from normal eyes. OCTA measurements can be affected by various subject-related, eye-related, and disease-related factors. Vessel density reduction on OCTA reaches a base level (floor) at a more advanced disease stage than the structural changes on OCT and therefore has the potential to monitor progression in eyes with advanced glaucomatous damage. OCTA also adds information about glaucoma patients at risk of faster progression. OCTA, therefore, complements visual field and OCT examinations to diagnose glaucoma, detect progression, and assess risk of progression.

The role of cldnh during the early retinal development in zebrafish

Claudin-3, an integral component of tight junction, has recently been shown to be expressed in retinal ganglion cells, retinal pigment cells, and retinal vascular endothelial cells. However, the role of claudin-3 in the development of the neural retina and its vessels remains undefined. This study aimed to investigate the role of zebrafish claudin-h (cldnh), the closest ortholog of mouse and human claudin-3, in the development of the neural retina and its vessels. Cldnh levels in green fluorescent protein transgenic zebrafish were genetically manipulated by cldnh morpholino oligonucleotide (MO) and cldnh mRNA to investigate gene function. The expression of cldnh was analyzed using polymerase chain reaction and immunofluorescence staining. The altered morphological, cellular and molecular events in the cldnh MO-morphant eyes were detected using hematoxylin-eosin staining, fluorescent dye injection, confocal in vivo imaging, BrdU labeling, TUNEL assay, RNA sequencing, and Western blot. We demonstrated that the cldnh protein was expressed in the neural retina and the hyaloid vessel which is the predecessor of the retinal vessel in zebrafish. Cldnh knockdown delayed lamination of the neural retina and reduced its thickness, which might be associated with the downregulation of the retinal development-related genes of atoh7, pcdh17, crx, neurod1, insm1a, sox9b and cdh11, and the upregulation of the cell cycle and apoptosis-associated genes of tp53, cdkn1a and casp8. Cldnh knockdown also reduced the density and interrupted the lumenization of the hyaloid vessels, which might be owing to the downregulation of the vessel formation-related genes of hlx1 and myl7. In conclusion, cldnh was required for the normal development of the neural retina and its vessels in zebrafish, providing a basis for elucidating its role in the pathogenesis of retinal vascular or inflammatory diseases.

Comparison of vessel density in macular and peripapillary regions between primary open-angle glaucoma and pseudoexfoliation glaucoma using OCTA

PURPOSE

The aim of our study was to compare macular and peripapillary vessel density using optical coherence tomography angiography (OCTA) between eyes with primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG).

METHODS

Thirty-six POAG and 34 PXG eyes with similar visual field defect (no statistically significant difference between average mean deviation and pattern standard deviation scores) were included. Macular superficial vessel density (msVD) in the superficial macular layer and foveal avascular zone (FAZ) parameters were assessed with (6 × 6 mm) and peripapillary vessel density (ppVD) in the radial peripapillary capillary (RPC) with (4.5 × 4.5 mm) OCTA scans. Area under the receiver operating curve was used for assessing diagnostic capability.

RESULTS

In PXG group, all msVD parameters had lesser values, and especially in parafoveal region, statistically significant decrease was shown (p = 0.008) in all subdivisions except nasal (p = 0.053). FAZ area was more larger in PXG [0.32(0.25-0.36)] than POAG [0.28(0.22-0.39)],(p = 0.944). FAZ density - 300 μm had statistically significant decrease in PXG (47.22 ± 6.92) according to POAG groups (50.63 ± 7.25) (p = 0.048). Most of RPC VD parameters had decreasing values in PXG group (p > 0.05). VDs and corresponding thicknesses had significant remarkable positive correlation in both macular and peripapillary regions. Significant remarkable negative correlations were observed between fovea VD and FAZ area, FAZ perimeter and between fovea thickness and FAZ area, FAZ perimeter.

CONCLUSION

PXG eyes were found to have lesser values in terms of VD in the macular area, especially in the parafoveal and FD-300 regions, compared to POAG eyes which had similar functional and structural glaucomatous damage. Patients whose etiology was PXG and who seemed to have the same functional damage as those with POAG were actually found to have greater macular vascular damage. In addition, it was observed that macular vascular parameters correlated with peripapillary vascular parameters.

Evaluation of Diurnal Fluctuation in Parafoveal and Peripapillary Vascular Density Using Optical Coherence Tomography Angiography in Patients with Exfoliative Glaucoma and Primary Open-Angle Glaucoma

PURPOSE

To determine the diurnal variations in parafoveal and peripapillary vessel density using optical coherence tomography angiography in patients with exfoliative glaucoma, patients with primary open-angle glaucoma and healthy individuals.

MATERIALS AND METHODS

In this prospective cross-sectional study, 36 exfoliative glaucoma patients, 34 primary open-angle glaucoma patients and 35 healthy individuals were examined. Optical coherence tomography angiography was used for examining the vessel density of peripapillary (radial peripapillary capillary) and parafoveal (superficial layer) regions. Optical coherence tomography angiography readings were obtained at 09:00, 11:00, 14:00 and 16:00 on the same day. Intraocular pressure values were assessed accordingly. The intraclass correlation coefficients were used to evaluate test-retest variability.

RESULTS

Diurnal variation in intraocular pressure or vessel density values was not found in any parafoveal or peripapillary region in any of the groups at any hour of measurement. The vessel density in the temporal sector of the exfoliative glaucoma group was significantly lower than in the primary open-angle glaucoma group at all time points. (Mann-Whitney U test; 09:00, P= .015; 11:00, P= .002; 14:00, P= .040; and 16:00, P= .048, respectively). The test-retest repeatability was high and almost excellent for the parafoveal and peripapillary regions in each group (XFG range: 0.757 - 0.985, POAG range: 0.834 - 0.985, and control range: 0.708 - 0.983).

CONCLUSIONS

It may be important to estimate the diurnal fluctuation occurring in retinal haemodynamics in patients with exfoliative glaucoma and primary open-angle glaucoma despite the lack of any considerable variation in intraocular pressure and retinal vessel density values in one day. The study found that at any point of time, vessel density of radial peripapillary capillary in temporal region was lower in exfoliative glaucoma patients than in primary open-angle glaucoma patients having the same glaucoma severity.

Optical coherence tomography angiography of the peripapillary region and macula in normal, primary open angle glaucoma, pseudoexfoliation glaucoma and ocular hypertension eyes

AIM

To evaluate and compare the peripapillary and retinal vasculature changes in primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), ocular hypertension (OHT) and normal eyes using optical coherence tomography angiography (OCTA).

METHODS

A total of 114 POAG, PXG and OHT eyes of 60 patients and 46 eyes of 23 healthy control participants with good quality OCTA images were included. The PXG, POAG, OHT, and control groups (aged 68.17±6.30y, 61.11±10.26y, 58.1±8.9y, and 56.9±4.6y, respectively) contained of 46, 36, 32, and 46 eyes, respectively. Measurements of vessel density (VD) in the peripapillary region and macula, average retinal inner thickness, and retinal nerve fiber layer thickness (RNFLT) were compared among groups. In order to test the accuracy of differentiation between eyes with and without glaucoma, the area was calculated under the receiver operating characteristic (ROC) curves.

RESULTS

The VD in glaucomatous eyes was significantly lower than the control group in all peripapillary sectors (44.35%±6.78% vs 50.47%±1.83%, P<0.001), the superficial (44.08%±5.46% vs 51.28%±2.85%, P<0.001) and the deep (45.13%±8.55% vs 54.20%±5.44%, P<0.001) vascular plexus. There was a significant difference in peripapillary VD between glaucomatous and OHT eyes (44.35%±6.78% vs 49.86%±2.45%, P<0.001). The OHT group featured a lower superficial (48.06%±4.32% vs 51.28%±2.85%, P=0.027) and deep plexus (48.70%±5.99% vs 54.20%±5.44%, P=0.013) whole image vessel density (wiVD) than did the control group. The average macular superficial plexus wiVD was significantly lower in eyes with PXG than in eyes with POAG (42.22%±5.36% vs 46.54%±5.56%, P=0.046).

CONCLUSION

OCTA can measure reduced peripapillary and macular VD in eyes with glaucoma and OHT, and these results are correlated to functional and structural glaucomatous alterations. Peripapillary and macular superficial plexus VD is lower in eyes with PXG than in eyes with POAG. Furthermore, the OHT eyes demonstrate impaired macular vasculature in both superficial and deep plexus.

Quantitative analysis of radial peripapillary capillary plexuses in patients with clinically unilateral pseudoexfoliation syndrome

PURPOSE

The aim of this study was to image the radial peripapillary capillary vessel densities (RPCvds) of the affected eyes and fellow unaffected eyes of individuals with unilateral pseudoexfoliation syndrome (PES) using optical coherence tomography angiography (OCTA) and to compare the RPCvds with those of normal age-matched individuals.

METHODS

The eyes were divided into three groups: the pseudoexfoliative material (PXM)-positive eyes of patients with clinically unilateral PES (study eyes), the fellow eyes of the PXM-positive patients (fellow eyes), and the eyes of healthy patients (control eyes). Those patients with glaucomatous findings, including peripapillary hemorrhaging, cupping, notching, focal thinning of the neuroretinal rim, or intraocular pressure readings greater than 21 mmHg, were excluded from the study. The RPCvd (%), peripapillary retinal nerve fiber layer (RNFL) thickness (μm), cup/disc area ratio, rim area (mm²), disc area (mm²), and cup volume (mm³) were automatically calculated via OCTA.

RESULTS

This cross-sectional comparative prospective study included 128 eyes of 88 patients: 40 PXM-positive eyes, 40 fellow eyes, and 48 control eyes. The RPCvds and RNFL thicknesses in the peripapillary region were significantly lower in the study eyes than in the fellow eyes and the control eyes (p = 0.011 and p = 0.011, p = 0.009 and p = 0.004, respectively). There were no significant differences between the fellow eyes and the control eyes with regard to the RPCvd and RNFL values in any region (p > 0.05 for all).

CONCLUSION

Lower RPCvds could provoke capillary deficiency and deterioration of the perfusion of the optic nerve head in patients with PES.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

Macular Vascularity in Ischemic Optic Neuropathy Compared to Glaucoma by Projection-Resolved Optical Coherence Tomography Angiography

PURPOSE

To compare macular vasculature in patients with primary open-angle glaucoma (POAG) and atrophic nonarteritic anterior ischemic optic neuropathy (NAION).

DESIGN

Prospective, cross-sectional study.

METHODS

Thirty-seven eyes with moderate and advanced POAG, 19 eyes with atrophic NAION, and 40 eyes of normal subjects were imaged using optical coherence tomography angiography (OCT-A). Macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thicknesses were measured in addition to macular superficial and deep vasculature after projection removal using custom software.

RESULTS

Linear models showed that while averaged peripapillary RNFL and macular GCC were not different between NAION and POAG eyes, both were significantly thinner than control eyes. Whole image macular superficial vessel density was significantly lower in NAION and glaucoma eyes (P = .003 and <.001, respectively) than in normal eyes, with lower vessel density in glaucoma than in NAION eyes (P = .01). Whole image and parafoveal deep macular vessels in glaucoma eyes (21.0%±8.7%, 24.4%±9.6%) were significantly lower than in control eyes (27.4%±8.6%, 31.9%±10.6%) (P = .01 and P = .01, respectively). No significant differences in deep vessels were observed between NAION and control eyes. Glaucomatous eyes had lower temporal and inferior parafoveal deep vasculature values than NAION eyes (P = .007 and .03, respectively).

CONCLUSIONS

In NAION and POAG with similar RNFL and macular damage, macular OCT-A shows less involvement of superficial and deep vascular plexus in NAION in contrast to POAG, which might show a primary vascular insult in addition to secondary vascular damage due to ganglion cell damage.

Comparison of the retinal nerve fiber layer and ganglion cell complex thickness in Korean patients with unilateral exfoliation syndrome and healthy subjects

Purpose

To compare retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness in patients with unilateral exfoliation syndrome (XFS) and age-matched controls using spectral domain-optical coherence tomography (SD-OCT).

Materials and methods

This prospective case–control study included 54 eyes (the XFS-affected and the fellow eyes) of 27 unilateral XFS patients and 27 eyes of 27 age-matched control subjects. The RNFL and GCC thicknesses were measured using SD-OCT (RT-Vue 100, Optovue, Fremont, CA) after pupillary dilation. RNFL and GCC thicknesses were compared between case and control groups.

Results

The mean age of XFS patients was 73.3 years and that of age-matched controls was 74.3 years. Both groups demonstrated a male preponderance. Superior RNFL thickness of XFS-affected eyes were significantly thinner than those of the healthy age-matched controls (P = 0.002 by ANOVA). There were no statistically significant differences in the RNFL thickness between both eyes of unilateral XFS patients. Moreover, superior GCC thickness of both eyes in unilateral XFS patients were thinner than those in controls (P = 0.002 by ANOVA).

Conclusions

Thinner RNFL and GCC thicknesses were observed in unilateral XFS patients without visual field defects. These findings imply that XFS itself might be a risk factor for development of glaucomatous optic disc and RNFL damage.