Evaluation of Parapapillary Choroidal Microvasculature Dropout and Progressive Retinal Nerve Fiber Layer Thinning in Patients With Glaucoma

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.

Rates of Choriocapillaris Microvascular Dropout and Macular Structural Changes in Glaucomatous Optic Neuropathy With and Without Myopia

PURPOSE

To evaluate the association between rates of juxtapapillary choriocapillaris microvasculature dropout (MvD) change and rates of ganglion cell inner plexiform layer (GCIPL) loss in primary open-angle glaucoma (POAG) and glaucoma suspect eyes with and without myopia.

DESIGN

Cohort study from clinical trial data METHODS: 238 eyes from 155 POAG and glaucoma suspect patients were stratified into no-myopia (axial length (AL) ≤ 24 mm; n = 78 eyes), mild myopia (24 mm< AL ≤ 26 mm; n = 114 eyes), and high myopia (AL > 26 mm; n = 46 eyes). Eyes with a minimum of 3 visits and 1.5 years of follow-up with both optical coherence tomography angiography (OCT-A) and OCT macula scans were included. Presence, area, and angular circumference of juxtapapillary MvD were evaluated on en face choroidal images and horizontal B-scans obtained from OCT-A imaging.

RESULTS

Over the mean follow-up of 4.4 years, the mean MvD area rates of change (95% CI) were largest in high and mild myopia group (0.04 (0.03, 0.05) mm2/year in both groups), followed by the no-myopia group (0.03 (0.02, 0.04) mm2/year). The mean MvD angular circumference rates of change (95% CI) were highest in mild myopia group (8.7o (6.9o, 10.5o)/year) followed by the high myopia and no-myopia groups (8.1o (5.3o, 10.9o)/year, and 7.4o (5.3o, 9.6o)/year, respectively). While the mean global GCIPL thinning rates between eyes with MvD at baseline compared to eyes without were similar in all myopia groups, the rates of MvD area change were significantly faster in all myopia groups with baseline MvD (all p≤0.004). Significant faster rates of MvD angular circumference change were found in the mild myopia group with baseline MvD (p<0.001) only. In multivariable models, the rates of GCIPL thinning over time were significantly associated with rates of MvD angular circumference change and MvD area change (R2=0.33, p<0.001 and R2=0.32, p=0.006, respectively).

CONCLUSIONS

Rates of GCIPL thinning were associated with rates of MvD area and angular circumference change over time in myopic POAG eyes. Utilizing OCT-A to detect MvD may provide an additional tool for monitoring macular structural changes in glaucomatous eyes with myopia.

Systemic Arterial Stiffness and Choroidal Microvascular Insufficiency on the Structural Progression of Normal Tension Glaucoma

PURPOSE

To identify the role of systemic arterial stiffness and choroidal microvascular insufficiency on structural progression of normal-tension glaucoma (NTG).

DESIGN

Retrospective cohort study.

METHODS

A total of 107 early NTG eyes of 88 patients, who underwent pulse wave velocity (PWV) measurements and optical coherence tomography (OCT) angiography (OCT-A) at baseline, were categorized depending on the presence of peripapillary choroidal microvasculature dropout (MvD) and PWV. Differences in glaucomatous progression were analyzed. Structural progression rates were determined using the trend-based analysis of Cirrus OCT.

RESULTS

Thirty-two eyes displayed choroidal MvD (62.7 [95% CI 58.4-67.0] years old, 53.6% males), and 70 eyes did not show any MvD (59.9 (95% CI 57.1-62.6) years old, 53.3% males) at baseline. Patients were followed for 48.4 (95% CI 40.0-56.8) months. When they were further divided based on PWV (high PWV ≥ 1400 cm/sec), those with choroidal MvD and high PWV showed significantly faster thinning in macular ganglion cell-inner plexiform layer (GCIPL; P = .023). In comparison to those with low PWV and no MvD, eyes with high PWV and MvD in the peripapillary area were likely to show fast structural progression (≤-1.2 µm/year) in the macular GCIPL by odds of 6.019 (95% CI 1.619-38.531, P = .025).

CONCLUSIONS

In NTG eyes, GCIPL thinning was faster when choroidal MvD and high systemic arterial stiffness were present. The simultaneous presence of regional and systemic vascular insufficiency may be associated with rapid glaucoma structural progression in eyes with low baseline intraocular pressure.

Underlying Microstructure of the Lamina Cribrosa at the Site of Microvasculature Dropout

Purpose

To determine the microstructure of the lamina cribrosa (LC) associated with microvasculature dropout (MvD) of the deep optic nerve head (ONH) in primary open-angle glaucoma (POAG) and to identify factors related to the presence of MvD.

Methods

POAG eyes that exhibited MvD in the LC (MvD-LC) or MvD in the peripapillary choroid (MvD-PC) underwent optical coherence tomography and optical coherence tomography angiography (OCTA) to evaluate the structure and microvasculature of the deep ONH, respectively. The presence of MvD-LC or MvD-PC was determined using en face OCTA images of the deep ONH. The sectoral LC thickness (LCT) and LC curvature index (LCCI) (at MvD-LC site, when applicable), the mean LCT and LCCI of the global ONH, and other clinical characteristics were measured and compared between eyes with and without MvD-LC.

Results

The study included 93 eyes with and 51 without MvD-LC. The presence of MvD-LC was associated with lower sectoral LCT (odds ratio [OR] = 0.96, P < 0.001) and mean LCT (OR = 0.97, P = 0.032), larger visual field pattern standard deviation (PSD; OR = 1.20, P = 0.038), and higher pretreatment intraocular pressure (IOP; OR = 1.22, P = 0.012). Fifteen percent of the eyes with MvD-LC (14/93) did not present MvD-PC. Those eyes had younger age (P = 0.043), thicker juxtapapillary choroid (P = 0.018), larger sectoral LCCI (P = 0.040), thicker retinal nerve fiber layer (P = 0.024), smaller PSD (P = 0.008), and higher pretreatment IOP (P = 0.006) than those with both MvD-LC and MvD-PC.

Conclusions

MvD-LC was associated with a localized morphologic alteration of the LC, and eyes with MvD-LC tended to have a higher pretreatment IOP. The clinical implications of MvD-LC should differ from those of MvD-PC in eyes with POAG.

Ocular blood flow biomarkers may predict long-term glaucoma progression

BACKGROUND/AIM

To examine the relationship between baseline blood flow biomarkers and long-term open-angle glaucoma (OAG) progression.

METHODS

112 patients with early to moderate OAG (mean age 64.9±11.0 years; 68 female) were evaluated at baseline and every 6 months from 2008 to 2013. Biomarkers of retinal capillary blood flow were assessed by Heidelberg retinal flowmetry. Functional disease progression was monitored via Humphrey visual field examinations, defined as two consecutive visits with a mean deviation decrease ≥2 decibels and/or Advanced Glaucoma Intervention Study score increase ≥2 compared with baseline. Structural progression was monitored with optical coherence tomography and Heidelberg retinal tomograph, defined as two consecutive visits with retinal nerve fibre layer thickness decrease ≥8% and/or horizontal or vertical cup/disk ratio increase ≥0.2 compared with baseline. Mixed-model analysis of covariance was used to test for significant change from baseline to 5-year follow-up. Times to functional and structural progression were analysed using Cox proportional hazards models.

RESULTS

Lower HRF retinal capillary blood flow in the superior retina was significantly associated with structural progression (p=0.0009).

CONCLUSION

In our OAG sample, baseline lower retinal capillary perfusion in the superior retina was predictive of structural progression after 5 years.

TRIAL REGISTRATION NUMBER

NCT01145911.

Comparative features of superior versus inferior hemisphere microvasculature dropout in open-angle glaucoma

PURPOSE

This study aimed to investigate differences in microvasculature dropout (MvD) between the superior and inferior hemispheres in glaucoma patients.

STUDY DESIGN

Retrospective and cross-sectional.

METHODS

Fifty-eight eyes of 58 open-angle glaucoma patients (age 61.12 ± 10.19 years, mean deviation - 7.32 ± 6.36 dB) were included. MvD was detected with en face images from swept-source optical coherence tomography angiography. Blood flow at the optic nerve head was measured with laser speckle flowgraphy, represented as the mean blur rate in tissue (MBRT). Logistic and linear regression models adjusted for age, intraocular pressure, axial length, and circumpapillary retinal nerve fiber layer thickness were used to investigate the relationship between various factors and MvD angle in each hemisphere.

RESULTS

The presence of inferior MvD was related to peripapillary atrophy-β area (odds ratio = 14.10 [2.49-234.00], P = 0.019). Superior MvD angle was significantly related to MBRT in the superior quadrant (β = -0.31 [- 0.60 - -0.02], P = 0.037). Inferior MvD angle was significantly related to peripapillary atrophy-β area (β = 0.49 [0.21-0.77], P = 0.001).

CONCLUSIONS

Only superior MvD demonstrated a significant relationship with reduced ocular blood flow. In contrast, inferior MvD was associated with mechanical stress. These findings may suggest a potential difference in pathophysiology between superior and inferior MvD.

Reduction of Optic Disc Microvasculature and Retinal Nerve Fiber Layer Thinning in Patients With Glaucoma

PURPOSE

To assess the relationship between the change of optic disc vessel density (ODVD) and retinal nerve fiber layer (RNFL) thinning in primary open-angle glaucoma (POAG) patients.

DESIGN

Retrospective case series.

METHODS

For 105 POAG patients, ≥5 consecutive optical coherence tomography (OCT) and OCT angiography images were obtained during ≥2 years of follow-up. Based on enface OCT angiography imaging, ODVD was calculated as the ratio of pixels occupied by vessels below the internal limiting membrane within the temporal area of the optic cup, and ODVD reduction was determined when there was a statistically significant negative slope (P < .05) for any of the global, superior, or inferior sectors. The association between the rates of ODVD change and RNFL thinning was assessed by a multivariable longitudinal linear mixed-effects model versus time.

RESULTS

During 2.9 ± 0.3 years of follow-up on the 105 participants with visual field mean deviation at baseline of -5.7 ± 4.8 dB, 46 (43.8%) showed ODVD reduction. Faster global RNFL thinning was associated with the smaller Bruch's membrane opening area (ß = 0.381; 95% confidence interval [CI], 0.120-0.646; P = .006), optic disc hemorrhage (ß = -0.567; 95% CI, -0.909 to -0.228; P = .002), and faster rate of global ODVD change (ß = -0.090; 95% CI, -0.139 to -0.042; P = .001).

CONCLUSIONS

Reduction of optic disc microvasculature was associated with rapid RNFL thinning in POAG. This suggests a role for deep optic nerve head circulation in the glaucoma pathogenesis.

Optic neuropathy in high myopia: Glaucoma or high myopia or both?

Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much attention. Evidence has shown that high myopia is related to the development of glaucomatous or glaucoma-like optic neuropathy, and that both have many common features. These similarities often pose a diagnostic challenge that will affect the future management of glaucoma suspects in high myopia. In this review, we summarize similarities and differences in optic neuropathy arising from non-pathologic high myopia and glaucoma by considering their respective structural and functional characteristics on fundus photography, optical coherence tomography scanning, and visual field tests. These features may also help to distinguish the underlying mechanisms of the optic neuropathies and to determine management strategies for patients with high myopia and glaucoma.

Central visual field damage in glaucoma eyes with choroidal microvasculature dropout with and without high axial myopia

PURPOSE

To characterise the relationship between a deep-layer microvasculature dropout (MvD) and central visual field (VF) damage in primary open-angle glaucoma (POAG) patients with and without high axial myopia.

DESIGN

Cross-sectional study.

METHODS

Seventy-one eyes (49 patients) with high axial myopia and POAG and 125 non-highly myopic POAG eyes (97 patients) were enrolled. Presence, area and angular circumference of juxtapapillary MvD were evaluated on optical coherence tomography angiography B-scans and en-face choroidal images.

RESULTS

Juxtapapillary MvD was detected more often in the highly myopic POAG eyes (43 eyes, 86%) than in the non-highly myopic eyes (73 eyes, 61.9%; p=0.002). In eyes with MvD, MvD area and angular circumference (95% CI) were significantly larger in the highly myopic eyes compared with the non-highly myopic eyes (area: (0.69 (0.40, 0.98) mm2 vs 0.31 (0.19, 0.42) mm2, p=0.011) and (angular circumference: 84.3 (62.9, 105.8) vs 74.5 (58.3, 90.9) degrees, p<0.001), respectively. 24-2 VF mean deviation (MD) was significantly worse in eyes with MvD compared with eyes without MvD in both groups (p<0.001). After adjusting for 24-2 MD VF, central VF defects were more frequently found in eyes with MvD compared with eyes without MvD (82.7% vs 60.9%, p<0.001). In multivariable analysis, higher intraocular pressure, worse 24-2 VF MD, longer axial length and greater MvD area and angular circumference were associated with worse 10-2 VF MD.

CONCLUSIONS

MvD was more prevalent and larger in POAG eyes with high myopia than in non-highly myopic POAG eyes. In both groups, eyes with MvD showed worse glaucoma severity and more central VF defects.

Diagnostic performance of wide-field optical coherence tomography angiography for high myopic glaucoma

Diagnosing and monitoring glaucoma in high myopic (HM) eyes are becoming very important; however, it is challenging to diagnose this condition. This study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (WF-OCTA) maps for the detection of glaucomatous damage in eyes with HM and to compare the diagnostic ability of WF-OCTA maps with that of conventional imaging approaches, including swept-source optical coherence tomography (SS-OCT) wide-field maps. In this retrospective observational study, a total 62 HM-healthy eyes and 140 HM eyes with open-angle glaucoma were included. Patients underwent a comprehensive ocular examination, including SS-OCT wide-field and 12 × 12 WF-OCTA scans. The WF-OCTA map represents the peripapillary and macular superficial vascular density maps. Glaucoma specialists determined the presence of glaucomatous damage in HM eyes by reading the WF-OCTA map and comparing its sensitivity and specificity with those of conventional SS-OCT images. The sensitivity and specificity of 12 × 12 WF-OCTA scans for HM-glaucoma diagnosis were 87.28% and 86.94%, respectively, while, the sensitivity and specificity of SS-OCT wide-field maps for HM-glaucoma diagnosis were 87.49% and 80.51%, respectively. The specificity of the WF-OCTA map was significantly higher than that of the SS-OCT wide-field map (p < 0.05). The sensitivity of the WF-OCTA map was comparable with that of the SS-OCT wide-field map (p = 0.078). The WF-OCTA map showed good diagnostic ability for discriminating HM-glaucomatous eyes from HM-healthy eyes. As a complementary method to an alternative imaging modality, WF-OCTA mapping can be a useful tool for the detection of HM glaucoma.

Relationship of Choroidal Microvasculature Dropout and Beta Zone Parapapillary Area With Visual Field Changes in Glaucoma

PURPOSE

To evaluate the association between rates of choroidal microvasculature dropout (MvD) change, beta zone parapapillary atrophy (β-PPA) area change, and visual field (VF) changes in eyes with primary open-angle glaucoma (POAG).

DESIGN

Retrospective, observational cohort study.

METHODS

In a tertiary glaucoma clinic, we included 76 eyes from 58 patients with POAG with and without localized MvD, who had ≥2 years of follow-up with a minimum of 4 visits with optical coherence tomography angiography and optical coherence tomography scans. β-PPA area was evaluated using scanning laser ophthalmoscopy-like images and compared with the area of MvD on an en face choroidal vessel density map during the follow-up period. Joint longitudinal mixed effects models were used to estimate the rates of change in β-PPA area or MvD area and VF mean deviation (MD).

RESULTS

Mean rates of change in β-PPA and MvD area were 0.037 mm2 (95% confidence interval [CI] 0.030-0.043 mm2) per year and 0.039 mm2 (95% CI 0.029-0.048 mm2) per year, respectively, over the mean follow-up of 4.1 years. In multivariable models, MvD area enlargement was significantly associated with faster rates of VF MD loss (0.03 mm2 [95% CI 0.02-0.04 mm2] per 1-dB worse, P < .001) but not β-PPA area enlargement (0.04 mm2 [95% CI 0.03-0.05 mm2] per 1-dB worse, P = .252).

CONCLUSION

MvD area rates, but not β-PPA area rates, were associated with VF MD loss changes in eyes with POAG. Assessment of MvD is useful for the detection of patients with glaucoma who are at an increased risk of faster VF loss.

Parapapillary choroidal microvasculature dropout in eyes with primary open-angle glaucoma

The purpose of this study was to evaluate how various parameters are related to microvasculature dropout (MvD) area measured using optical coherence tomography angiography (OCTA). We measured the area of MvD in 55 patients with primary open-angle glaucoma (POAG). Using OCTA, MvD area and peripapillary choroidal atrophy (PPA) area were assessed in a 4.5 mm × 4.5 mm region. The following were examined: circumpapillary nerve fiber layer (cpRNFL) thickness, optic disc area, optic disc cupping area, optic disc rim area, Humphrey Field Analyzer (HFA) 24/10-2 mean deviation (MD), and pattern standard deviation (PSD). The relationship between MvD area and each parameter was evaluated using Spearman's rank correlation coefficient analysis. Mean MvD area and PPA area were 0.18 ± 0.17 mm2 and 1.13 ± 0.72 mm2, respectively. MvD area was significantly correlated with optic disc rim area (p = 0.0017), cpRNFL (p = 0.0027), HFA 24/10-2 MD, and PSD (p < 0.001). In eyes with POAG, MvD area indicates the severity of glaucoma, which might be associated with structural changes in the peripapillary vasculature around the optic disc.

Comparison of the Choroid in Primary Open Angle and Angle Closure Glaucoma Using Optical Coherence Tomography

PRCIS

The current study highlights distinct choroidal alterations in primary open angle (POAG) and primary angle closure (PACG) glaucomas, underscoring the potential of the Choroidal Vascularity Index (CVI) as a valuable indicator for understanding glaucoma pathogenesis.

PURPOSE

To evaluate choroidal structural changes in patients with POAG and PACG and healthy controls utilizing the CVI and subfoveal choroidal thickness by enhanced depth imaging optical coherence tomography.

METHODS

This study was cross-sectional. A total of 171 eyes of 171 subjects, comprising 69 eyes with untreated POAG, 58 eyes with untreated PACG, and 44 healthy eyes, were enrolled in this study. Subfoveal choroidal thickness, luminal area (LA), stromal area (SA), and total choroidal area were measured on enhanced depth imaging-optical coherence tomography scans. The CVI parameter is calculated as the proportion of LA to the total choroidal area.

RESULTS

This study included 69 patients with POAG with a mean age of 51.4 ± 13.3 years, 58 patients with PACG with a mean age of 57.0 ± 7.3 years, and 44 healthy subjects with a mean age of 51.11 ± 10.7 years. The CVI in the POAG and PACG groups was significantly lower than that in the control group ( P = 0.001 and P = 0.005, respectively); however, not significantly different between the two glaucoma groups ( P = 1.000). POAG eyes had significantly lower LA than PACG and controls ( P = 0.014 and P = 0.049, respectively), whereas PACG eyes had significantly greater SA than controls ( P = 0.041).

CONCLUSIONS

The CVI of POAG and PACG eyes was significantly lower than that of normal eyes. A reduced LA was observed mainly in eyes with POAG, and an increased SA was observed mainly in eyes with PACG. The role of the choroid may differ between POAG and PACG eyes.

Rate of Retinal Nerve Fiber Layer Thinning in Glaucomatous Eyes With Optic Disc and Parapapillary Deep-Layer Microvasculature Loss

PRCIS

Microvasculature dropout in the parapapillary choroidal layer was a more important biomarker of glaucomatous nerve fiber layer thinning when it presented with deep-layer microvasculature of the optic disc rather than when it presents by itself.

PURPOSE

To characterize open angle glaucoma eyes with optic nerve head deep-layer microvasculature dropout (MvD-D) and parapapillary choroidal layer microvasculature dropout (MvD-P) and compare their retinal nerve fiber layer (RNFL) thinning rate.

MATERIAL AND METHODS

This study included 122 open angle glaucoma eyes that underwent ≥5 serial spectral-domain optical coherence tomography scans during a mean follow-up of 5.4 years. Swept-source optical coherence tomography angiography was used to evaluate MvD-P and MvD-D. Subjects were classified into 3 groups according to the presence of MvD-P and MvD-D: (1) no dropout (n=37); (2) solely MvD-P (n=40), and (3) both MvD-P and MvD-D (n=45). The RNFL thinning rate was compared among the 3 groups, and the associated factors were assessed by Cox proportional hazard analysis.

RESULTS

RNFL thinning rates were highest in the group with both MvD-P and MvD-D, followed by the group with solely MvD-P and finally by the no dropout group (-0.24 vs. -0.65 vs. -1.20 μm/y, P <0.001). Thinner central corneal thickness [hazard ratio (HR)0.990, P =0.003], presence of disc hemorrhage (HR=1.802, P =0.035), and coexistence of MvD-P and MvD-D (HR=2.941, P <0.001) were the factors associated with RNFL thinning.

CONCLUSIONS

The coexistence of MvD-P and MvD-D was associated with faster RNFL thinning than MvD-P alone or no dropout, which suggested that observing the optic disc deep microvasculature along with parapapillary choroidal layer using Swept-source optical coherence tomography angiography may be clinically relevant in monitoring glaucoma progression.

Impact of smoking on choroidal microvasculature dropout in glaucoma: a cross-sectional study

OBJECTIVE

To investigate the effect of smoking on choroidal microvasculature dropout (MvD) in glaucoma.

DESIGN

Cross-sectional study.

SETTING

Tertiary glaucoma centre.

PARTICIPANTS

223 eyes of 163 patients with primary open-angle glaucoma who had undergone imaging with optical coherence tomography angiography and completed a questionnaire on smoking from the Diagnostic Innovations in Glaucoma Study.

PRIMARY OUTCOME MEASURES

Linear mixed-effects models were used to determine the effect of each parameter on MvD area and angular circumference. The sensitivity analysis was performed by categorising the glaucoma severity determined by visual field mean deviation (MD).

RESULTS

MvD was found in 37 (51.4%) eyes with smoking history and in 67 (44.4%) eyes with non-smokers (p=0.389). Larger MvD area and wider angular circumference were found in smokers compared with non-smokers (p=0.068 and p=0.046, respectively). In a multivariable model, smoking intensity was significantly associated with MvD area (0.30(95% CI 0.01 to 0.60) each 0.01 mm2 per 10 pack-years; p=0.044). In eyes with moderate-severe glaucoma (MD <-6), smoking intensity was associated with larger MvD area (0.47 (95% CI 0.11 to 0.83) each 0.01 mm2 per 10 pack-years; p=0.011), whereas no significant association was found in early glaucoma (MD ≥-6) (-0.08 (95% CI -0.26 to 0.11), p=0.401).

CONCLUSIONS

Smoking intensity was associated with larger choroidal MvD area in eyes with glaucoma, especially in patients with more severe disease.

TRIAL REGISTRATION NUMBER

NCT00221897.

Choroidal Microvasculature Dropout in Glaucoma

Glaucoma is a group of diseases characterized by distinctive visual field defect and optic nerve atrophy usually associated with elevated intraocular pressure (IOP). It is one of the most serious visual disorders and the leading cause of irreversible blindness worldwide. As a multifactorial disease, the pathogenesis of glaucoma is complicated and has been far from fully understood, where vascular factors are recognized to play an important role in its development and progression of glaucoma. Empirical researches have shown that parapapillary choroidal microvasculature dropout (CMvD) is closely associated with the impairment of optic nerve head (ONH) perfusion, probably accelerating the progression of glaucoma. Accordingly, it is necessary to explore the details regarding the relationship between CMvD and glaucoma progress, hoping to enhance the understanding of pathogenesis of glaucoma. In this review, we aimed to establish comprehensive understanding of the relationship between CMvD and glaucoma with generally going through relevant up-to-date literatures. Among the events that are closely associated with CMvD, we summarized the ones specifically involved in the term of glaucomatous pathological process, including thickness of retinal nerve fiber layer (RNFL) thickness, lamina cribrosa (LC) morphology, cricumpapillary vessel density (cpVD) and visual function such as visual field (VF) defect as well as the prognosis of glaucoma. Although researchers have made great advances, there are still many issues need to be addressed particularly concerning the pathogenic role of CMvD in glaucoma development and its clinical implications with respect to glaucoma prognosis.

Factors associated with choroidal microvascular dropout change

BACKGROUND/AIMS

To investigate the factors associated with choroidal microvasculature drop-out (MvD) enlargement detected by optical coherence tomography angiography (OCT-A) in glaucomatous eyes.

METHODS

Ninety-one eyes of 68 primary open-angle glaucoma patients were enrolled. Only eyes with a minimum of four good quality OCT-A and OCT scans of the optic nerve head acquired at least and with a minimum of 2 years follow-up were included. Area and angular circumference of MvD were analysed on en face images. Univariable and multivariable mixed effects models were constructed to identify the factors contributing to MvD area and angular circumference change over time.

RESULTS

Peripapillary MvD was detected in 53 (58.2%) eyes at baseline and in an additional 17 (18.6%) eyes during follow-up, whereas MvD was not detected in 21 (23.0 %) eyes during the entire follow-up period. In multivariable analysis, worse baseline visual field (VF) mean deviation (MD) (ß=0.27, 95% CI 0.10 to 0.44, p=0.002), greater intraocular pressure (IOP) fluctuations (ß=0.86, 95% CI 0.24 to 1.48, p=0.007), higher peak IOP (ß=0.17, 95% CI -0.01 to 0.35, p=0.067) and greater number of IOP lowering medications (ß=1.36, 95% CI 0.67 to 2.05, p<0.001) were associated with faster MvD area enlargement. Worse baseline VF MD and greater IOP fluctuation were also associated with significantly faster MvD circumferential enlargement in multivariable models.

CONCLUSION

Greater IOP fluctuation, higher peak IOP, worse baseline VF MD and greater number of glaucoma medications were significantly associated with MvD enlargement in glaucomatous eyes. The identification of factors associated with MvD enlargement may improve our understanding of the role of choroidal vasculature in glaucoma.

Change of Choroidal Microvasculature Dropout After Trabeculectomy as Assessed by Optical Coherence Tomography Angiography

PRCIS

Reduction in the angular circumference of choroidal microvascular dropout (CMvD AC) was found in POAG patients after trabeculectomy. Greater percentage of IOP reduction was significantly associated with decreased CMvD AC.

PURPOSE

The purpose of this study was to investigate the change of choroidal microvasculature dropout (CMvD) after trabeculectomy and its associated factors in primary open angle glaucoma (POAG) eyes using optical coherence tomography angiography.

METHODS

Fifty eyes of 50 POAG participants who had preoperative CMvD and underwent trabeculectomy were prospectively enrolled. Angular circumference (AC) of CMvD was determined from choroidal layer images by optical coherence tomography angiography preoperatively and at postoperative 1 year. The cutoff for significant AC of CMvD decrease was determined by the Bland-Altman method, and accordingly, patients were divided into 2, decreased and stable/increased CMvD AC groups. Changes in intraocular pressure (IOP) and CMvD AC were compared between the groups preoperatively and at postoperative 1 year. Factors associated with CMvD AC decrease were assessed by linear regression analysis.

RESULTS

The cutoff for significant CMvD AC decrease was 3.58 degrees; accordingly, 26 eyes (52.0%) were categorized as decreased CMvD AC group. No significant intergroup differences in baseline characteristics were found. However, the decreased CMvD AC group presented significantly lower IOP (10.7±3.7 vs. 12.9±2.6 mm Hg, P =0.022), lower CMvD AC (32.03±33.95% vs. 53.44±39.33%, P =0.044), and higher parapapillary choroidal vessel density ( P =0.014) compared with the increased/stable CMvD AC group at postoperative 1 year. The greater percentage of IOP reduction was significantly associated with decreased CMvD AC ( P =0.046).

CONCLUSIONS

CMvD AC reduction associated with IOP lowering was found after trabeculectomy. The long-term clinical relevance of postoperative CMvD reduction should be further investigated.

Temporal Optic Disc Microvasculature Dropout in Glaucoma

PURPOSE

To assess the clinical characteristics of focal temporal optic disc microvasculature dropout (MvD-D) in primary open-angle glaucoma (POAG) patients.

METHODS

One hundred and eighty-seven eyes of 187 POAG patients having MvD-D on Swept-Source optical coherence tomography angiography (SS-OCTA) were enrolled. Three groups were categorized according to the presence of temporal MvD-D within the upper and lower 45° of the fovea-Bruch's membrane (BM) opening axis: focal temporal MvD-D (Group 1, isolated focal temporal MvD-D; 44 eyes), supero/inferotemporal MvD-D (Group 2, MvD-D only in superotemporal or inferotemporal sector; 78 eyes), and diffuse temporal MvD-D (Group 3, MvD-D spanning ≥ 2 consecutive sectors, at least one of which being temporal sector; 65 eyes).

RESULTS

Group 1 had a significantly longer axial length and β-zone parapapillary atrophy without BM. There also was a larger horizontal tilt angle and ovality index than the other two groups (P < 0.001). Group 1 had a significantly thinner retinal nerve fiber layer (RNFL) in the temporal sector than did Group 2 (P < 0.001), despite similar thicknesses in all other areas (P > 0.05). Group 3 had significantly worse visual field mean deviation and thinner RNFL than the other two groups in all areas other than the nasal, temporal, and superotemporal sectors (P < 0.05).

CONCLUSIONS

Focal temporal MvD-D detected by SS-OCTA was associated with a longer axial length and related subsequent morphological changes of the optic disc and parapapillary area. This suggests that stretching of the optic disc consequent on axial elongation may lead to absence of temporal optic disc microvasculature.

Optical Coherence Tomography and Optical Coherence Tomography Angiography: Essential Tools for Detecting Glaucoma and Disease Progression

Early diagnosis and detection of disease progression are critical to successful therapeutic intervention in glaucoma, the leading cause of irreversible blindness worldwide. Optical coherence tomography (OCT) is a non-invasive imaging technique that allows objective quantification in vivo of key glaucomatous structural changes in the retina and the optic nerve head (ONH). Advances in OCT technology have increased the scan speed and enhanced image quality, contributing to early glaucoma diagnosis and monitoring, as well as the visualization of critically important structures deep within the ONH, such as the lamina cribrosa. OCT angiography (OCTA) is a dye-free technique for noninvasively assessing ocular microvasculature, including capillaries within each plexus serving the macula, peripapillary retina and ONH regions, as well as the deeper vessels of the choroid. This layer-specific assessment of the microvasculature has provided evidence that retinal and choroidal vascular impairments can occur during early stages of glaucoma, suggesting that OCTA-derived measurements could be used as biomarkers for enhancing detection of glaucoma and its progression, as well as to reveal novel insights about pathophysiology. Moreover, these innovations have demonstrated that damage to the macula, a critical region for the vision-related quality of life, can be observed in the early stages of glaucomatous eyes, leading to a paradigm shift in glaucoma monitoring. Other advances in software and hardware, such as artificial intelligence-based algorithms, adaptive optics, and visible-light OCT, may further benefit clinical management of glaucoma in the future. This article reviews the utility of OCT and OCTA for glaucoma diagnosis and disease progression detection, emphasizes the importance of detecting macula damage in glaucoma, and highlights the future perspective of OCT and OCTA. We conclude that the OCT and OCTA are essential glaucoma detection and monitoring tools, leading to clinical and economic benefits for patients and society.

Discrepancy between peripapillary retinal and choroidal microvasculature and the rate of localized retinal nerve fiber layer thinning in glaucoma

This observational case series study is conducted to compare the extent of microvasculature impairment in the peripapillary retina and choroid in eyes with primary open-angle glaucoma (POAG), and to investigate the association of the discrepancy between the microvasculature impairments of each layer with the rate of progressive retinal nerve fiber layer (RNFL) thinning. A total of 88 POAG eyes with a localized RNFL defect were enrolled, including 67 eyes with and 21 eyes without choroidal microvasculature dropout (CMvD). Circumferential widths of retinal microvascular impairment (RMvI) and CMvD were measured, and eyes were classified based on the relative width of CMvD to RMvI (CMvD/RMvI ratio). The rate of RNFL thinning was determined by linear regression based on ≥ 5 serial OCT examinations. Thinner global RNFL and worse visual field mean deviation at baseline were associated with a larger circumferential width of the RMvI, whereas the presence of cold extremities, lower mean arterial pressure and thinner juxtapapillary choroid were associated with a larger circumferential width of the CMvD. The rate of global RNFL thinning was faster in eyes with larger relative CMvD width than in eyes with equal CMvD and RMvI widths and in eyes without CMvD (P = 0.001). Lower mean arterial pressure (P = 0.041), larger CMvD width (P = 0.046), larger CMvD/RMvI ratio (P = 0.041), and detection of disc hemorrhage during the follow-up (P = 0.013) were significant factors associated with faster global RNFL thinning. Larger CMvD width relative to RMvI width may be indicative of an increased risk of faster RNFL thinning in POAG with localized RNFL defect. Comparing the microvasculature impairment in individual layers may help predict more rapid glaucoma progression.

Microvascular Alterations of Peripapillary Choriocapillaris in Young Adult High Myopia Detected by Optical Coherence Tomography Angiography

(1) Background: The microstructural alterations of the peripapillary choriocapillaris in high myopes remain elusive. Here, we used optical coherence tomography angiography (OCTA) to explore factors involved in these alterations. (2) Methods: This cross-sectional control study included 205 young adults' eyes (95 with high myopia and 110 with mild to moderate myopia). The choroidal vascular network was imaged using OCTA, and the images underwent manual adjustments to determine the peripapillary atrophy (PPA)-β zone and microvascular dropout (MvD). The area of MvD and the PPA-β zone, spherical equivalent (SE), and axial length (AL) were collected and compared across groups. (3) Results: The MvD was identified in 195 eyes (95.1%). Highly myopic eyes exhibited a significantly greater area for the PPA-β zone (1.221 ± 0.073 vs. 0.562 ± 0.383 mm², p = 0.001) and MvD (0.248 ± 0.191 vs. 0.089 ± 0.082 mm², p < 0.001) compared with mildly to moderately myopic eyes, and a lower average density in the choriocapillaris. Linear regression analysis showed that the MvD area correlated with age, SE, AL, and the PPA-β area (all p < 0.05). (4) Conclusions: This study found that MvDs represent choroidal microvascular alterations in young-adult high myopes, which were correlated with age, SE, AL, and the PPA-β zone. In this disorder, OCTA is important for characterizing the underlying pathophysiological adaptations.

Combining Optical Coherence Tomography and Optical Coherence Tomography Angiography Longitudinal Data for the Detection of Visual Field Progression in Glaucoma

PURPOSE

To use longitudinal optical coherence tomography (OCT) and OCT angiography (OCTA) data to detect glaucomatous visual field (VF) progression with a supervised machine learning approach.

DESIGN

Prospective cohort study.

METHODS

One hundred ten eyes of patients with suspected glaucoma (33.6%) and patients with glaucoma (66.4%) with a minimum of 5 24-2 VF tests and 3 optic nerve head and macula images over an average follow-up duration of 4.1 years were included. VF progression was defined using a composite measure including either a "likely progression event" on Guided Progression Analysis, a statistically significant negative slope of VF mean deviation or VF index, or a positive pointwise linear regression event. Feature-based gradient boosting classifiers were developed using different subsets of baseline and longitudinal OCT and OCTA summary parameters. The area under the receiver operating characteristic curve (AUROC) was used to compare the classification performance of different models.

RESULTS

VF progression was detected in 28 eyes (25.5%). The model with combined baseline and longitudinal OCT and OCTA parameters at the global and hemifield levels had the best classification accuracy to detect VF progression (AUROC = 0.89). Models including combined OCT and OCTA parameters had higher classification accuracy compared with those with individual subsets of OCT or OCTA features alone. Including hemifield measurements significantly improved the models' classification accuracy compared with using global measurements alone. Including longitudinal rates of change of OCT and OCTA parameters (AUROCs = 0.80-0.89) considerably increased the classification accuracy of the models with baseline measurements alone (AUROCs = 0.60-0.63).

CONCLUSIONS

Longitudinal OCTA measurements complement OCT-derived structural metrics for the evaluation of functional VF loss in patients with glaucoma.

The choroidal microvasculature of the parapapillary area as a biomarker of glaucoma development in the fellow eye of patients with unilateral glaucoma

PURPOSE

To investigate the factors associated with the development of glaucoma in the healthy eyes of unilateral glaucoma patients.

MATERIALS AND METHODS

This was a retrospective observational case series study. All participants had unilateral primary open-angle glaucoma at the initial visit and were divided into two groups: one in which the fellow eyes developed glaucoma during the follow-up period and one in which the fellow eyes remained healthy. A complete ophthalmic examination, including best-corrected visual acuity testing, slit-lamp examination, intraocular pressure measurement, retinal nerve fiber layer and optic disk photographs, a 30-2 visual field test, and optical coherence tomography with angiography, was performed over a follow-up period of at least 3 years.

RESULTS

A total of fifty-six patients were enrolled, and over the course of the study period, 11 patients developed glaucoma in the fellow eyes, while the fellow eyes of 45 patients remained healthy. At the baseline, the glaucomatous eye had a larger area of beta parapapillary atrophy, lower parapapillary choroidal vascular density (pCVD) within the area, and a lower prevalence of microvascular dropout than normal fellow eyes (P < 0.001, 0.013, 0.001, respectively). In the multivariate analysis, a reduced pCVD in the gamma parapapillary atrophy (γPPA) region was significantly associated with the development of glaucoma in normal eyes (odds ratio, 0.566; 95% CI, 0.342, 0.935; P = 0.026).

CONCLUSIONS

The pCVD within the γPPA region at baseline is the risk factor for the development of glaucoma in the normal fellow eye of patients with unilateral glaucoma.

Parapapillary Choroidal Microvasculature Predicts Diabetic Retinopathy Progression and Diabetic Macular Edema Development: A Three-Year Prospective Study

PURPOSE

To determine the predictive value of the microcirculation of the optic nerve head by swept-source optical coherence tomography angiography for identifying individuals with high risk of diabetic retinopathy (DR) progression and diabetic macular edema (DME) development.

DESIGN

Prospective observational cohort study.

METHODS

A total of 946 patients (1879 eyes) with type 2 diabetes mellitus were recruited who had no DR or mild nonproliferative DR at baseline, and no DME. All subjects underwent 3 × 3 mm swept-source optical coherence tomography angiography centered on the optic nerve head to generate angiograms in 4 layers: radial peripapillary plexus, superficial retinal capillary plexus (SCP), deep retinal capillary plexus, and choriocapillaris (CC). The CC flow deficit percentage (CC FD%), vessel density (VD), and perfusion density (PD) were quantified.

RESULTS

During the 3 consecutive years of follow-up, 312 eyes (16.60%) experienced DR progression and 115 eyes (6.12%) developed DME. The DR progression was related to a lower VD of the SCP (relative risk per standard deviation decrease, 95% confidence interval): 1.30, 1.14-1.48; P < .001), a lower PD of the SCP (1.41, 1.24-1.60; P < .001), a lower VD of the radial peripapillary plexus (1.23, 1.08-1.40; P = .002), and an elevated CC FD% (1.62, 1.40-1.88; P < .001). The DME occurrence was associated with a lower VD of SCP (1.35, 1.09-1.66; P = .005), a lower PD of SCP (1.29, 1.05-1.59; P = .016), and a higher CC FD% (1.29, 1.03-1.61; P < .001). The CC FD% significantly improved the predictive power, with the increase of the C-statistic for DR progression and DME occurrence by 3.83% (P = .002) and 5.24% (P < .001), respectively.

CONCLUSIONS

This study provides the first longitudinal evidence suggesting that peripapillary CC FD% can improve the prediction of DR progression and DME development beyond traditional risk factors.

Visualization of erythrocyte stasis in the living human eye in health and disease

Blood cells trapped in stasis have been reported within the microcirculation, but their relevance to health and disease has not been established. In this study, we introduce an in vivo imaging approach that reveals the presence of a previously-unknown pool of erythrocytes in stasis, located within capillary segments of the CNS, and present in 100% of subjects imaged. These results provide a key insight that blood cells pause as they travel through the choroidal microvasculature, a vascular structure that boasts the highest blood flow of any tissue in the body. Demonstration of clinical utility using deep learning reveals that erythrocyte stasis is altered in glaucoma, indicating the possibility of more widespread changes in choroidal microvascular than previously realized. The ability to monitor the choroidal microvasculature at the single cell level may lead to novel strategies for tracking microvascular health in glaucoma, age-related macular degeneration, and other neurodegenerative diseases.

Multipressure Dial Goggle Effects on Circumpapillary Structure and Microvasculature in Glaucoma Patients

PURPOSE

To evaluate the effects of pressure changes induced by a multipressure dial (MPD) on circumpapillary retinal nerve fiber layer (RNFL) and capillary density (CD) measurements in patients with glaucoma using OCT angiography (OCTA).

DESIGN

Prospective interventional study.

PARTICIPANTS

Twenty-four patients with primary open-angle glaucoma.

METHODS

One eye of each patient underwent negative pressure application with the MPD. The MPD alters intraocular pressure (IOP) relative to atmospheric pressure by generating a negative pressure vacuum within a goggle chamber that is placed over the eye. Each participant underwent serial high density OCTA imaging (AngioVue) of the optic nerve head at different negative pressure increments of -5 mmHg, starting from 0 mmHg, ending at -20 mmHg, and then returning to baseline. Images were acquired after 2 minutes of sustained negative pressure at each target pressure to allow for stabilization of the retinal structures and microvasculature. The RNFL thickness and CD measurements were automatically calculated using the native AngioVue software, and then exported for analysis.

MAIN OUTCOME MEASURES

The influence of different levels of negative pressure on circumpapillary RNFL thickness and CD measurements, assessed by a linear mixed-effects model with repeated measures.

RESULTS

The mean (± SD) age was 71.0 years (± 7.8 years), the baseline IOP was 17.5 mmHg (± 3.6 mmHg), and there was a mean 24-2 mean deviation of -2.80 dB (± 2.55 dB). Serial circumpapillary CD measurements showed a statistically significant dose-dependent increase from baseline, without negative pressure application, to the maximum negative pressure application of -20 mmHg (difference, 2.27%; P = 0.010). Capillary density measurements then decreased symmetrically when lowering the negative pressure to baseline. Circumpapillary CD measurements at target negative pressures of -10 mmHg, -15 mmHg, and -20 mmHg were significantly higher than the baseline measurements (all P values < 0.05). Circumpapillary RNFL thickness remained the same throughout different levels of negative pressure.

CONCLUSIONS

Circumpapillary CD measurements showed a dose-dependent increase with the induction of negative pressure, while RNFL thickness measurements remained unchanged.

The relationship between choroidal blood flow and glaucoma progression in a Japanese study population

PURPOSE

To determine whether choroidal blood flow (BF) is related to visual field (VF) defect severity and progression in eyes with open-angle glaucoma (OAG).

STUDY DESIGN

Retrospective and longitudinal.

METHODS

This study comprised 443 eyes of 285 OAG patients who underwent laser speckle flowgraphy (LSFG), optical coherence tomography, and visual-field (VF) testing at baseline. The patients were then observed for at least 2 years and at least 5 reliable VF tests were performed. In the LSFG images, we set regions of interest at the optic nerve head (ONH) and the parapapillary choroid to obtain ONH-tissue mean blur rate (MBR) and choroidal MBR, respectively. We used univariable and multivariable linear mixed-effects models to determine clinical factors associated with choroidal MBR at baseline. We also used a linear mixed-effects model to determine the contribution of ONH-tissue MBR and choroidal MBR to baseline mean deviation (MD) and to MD slope during follow-up, adjusting for potential confounding factors, including circumpapillary retinal nerve fiber layer thickness.

RESULTS

Choroidal MBR was associated with age, MD slope, and ONH-tissue MBR (β = -0.181, P = 0.001; β = 0.134, P = 0.002; β = 0.096, P = 0.049, respectively). ONH-tissue MBR was associated with both MD and MD slope (β = 0.146, P = 0.004; β = 0.152, P = 0.009, respectively), whereas choroidal MBR was associated only with MD slope (β = 0.147, P = 0.005).

CONCLUSION

LSFG-derived choroidal MBR might be a useful biomarker to predict VF defect progression in a Japanese population.

Correlation Between Enlargement of Retinal Nerve Fiber Defect Angle in En Face Imaging and Visual Field Progression

Purpose

Retinal nerve fiber layer defects (RNFLDs) become enlarged with glaucoma progression. We measured the RNFLD angle and investigated whether it was correlated with deterioration of the visual field in patients with glaucoma.

Methods

This study included 84 eyes of 84 patients with open-angle glaucoma (mean deviation [MD] = −6.51 ± 5.91 dB, follow-up period = 2.82 ± 0.74 years) with the RNFLDs, who underwent en face swept-source optical coherence tomography (SS-OCT) wide scans (12 × 9 mm) at least 6 times. The RNFLD angle was measured as the intersection between the RNFLD and a circle centered on the disc with a radius half the distance between the disc and the fovea. Slopes for the RNFLD angle, macular ganglion cell layer thickness (GCCT), and circumpapillary RNFL thickness (cpRNFLT) were compared with the MD slope, as measured with the Humphrey field analyzer 24-2 program.

Results

The correlation coefficients with MD slope were −0.67 for the RNFLD angle slope (P < 0.001), 0.15 for the macular GCCT slope (P = 0.163), and 0.04 for the cpRNFLT slope (P = 0.719). The RNFLD angle tended to increase as the number of disc hemorrhage occurrences increased (rs = 0.31, P = 0.004). The RNFLD angle slope also had good predictive power for glaucoma progression (area under the receiver operating characteristic curve = 0.88, 95% confidence interval = 0.81–0.95).

Conclusions

We found that the RNFLD angle slope was more closely associated with the MD slope than were other OCT parameters. This suggests that measurement of the RNFLD angle with en face OCT images could be effective in evaluating glaucoma progression.

Translational Relevance

Our study provides a method for monitoring glaucoma progression with SS-OCT.

Rates of Choroidal Microvasculature Dropout and Retinal Nerve Fiber Layer Changes in Glaucoma

PURPOSE

To evaluate the association between rates of choroidal microvasculature dropout (MvD) change and rates of circumpapillary retinal nerve fiber layer (cpRNFL) loss in primary open-angle glaucoma (POAG) eyes.

DESIGN

Cohort study from clinical trial data.

METHODS

A total of 91 eyes of 68 POAG patients with and without localized MvD at baseline with at least 4 visits and 2 years of follow-up with optical coherence tomography angiography (OCT-A) and OCT scans were included. Area and angular circumference of MvD were evaluated on OCT-A en face and B-scan choroidal vessel density images during the follow-up period. Joint longitudinal mixed effects models were used to estimate the rates of change in MvD area or angular circumference and RNFL thickness. Univariable and multivariable regressions were completed to identify the factors contributing to cpRNFL thinning.

RESULTS

MvD was identified in 53 eyes (58.2%) at baseline. Seventeen eyes (18.6%) that did not show MvD at baseline developed it over the follow-up period. Over a mean follow-up of 4.0 years, the mean rates of change in MvD area and angular circumference (95% CI) were 0.05 (0.04, 0.06) mm² per year and 13.2° (10.7°, 15.8°) per year, respectively. In multivariable models, the rate of cpRNFL thinning was significantly associated with the rates of change in MvD area and angular circumference (P = .008 and P = .009, respectively).

CONCLUSIONS

Rates of MvD area and angular circumference change over time were associated with concurrent rates of cpRNFL loss in POAG eyes.

Multilayer Macula Vessel Density and Visual Field Progression in Glaucoma

PURPOSE

To evaluate the association of macular superficial vessel density (SVD) and projection-resolved deep vessel density (DVD) with past visual field (VF) progression in patients with primary open-angle glaucoma.

DESIGN

Retrospective cohort.

METHODS

In this longitudinal study, 208 eyes of 147 patients with glaucoma from the Diagnostics Innovations in Glaucoma Study were included. Eligible participants were required to have at least five 24-2 VF tests over a minimum follow-up period of 3 years before macular optical coherence tomography angiography imaging. VF progression was defined based on both event-based pointwise linear regression and trend-based methods. The association of macular SVD and DVD with the probability and rate of past VF progression was evaluated using a linear mixed effects model.

RESULTS

Fifty-two (25%) eyes had VF progression based on the pointwise linear regression based criterion at the end of a mean ± standard deviation follow-up duration of 6.9 ± 1.2 years. In the event-based multivariable analysis, a lower baseline SVD was associated with a higher likelihood of past VF progression (odds ratio per 1% lower. 1.28; 95% confidence interval, 1.02-1.59). Similarly, in the trend-based multivariable analysis, lower macular SVD was associated with a faster past rate of mean deviation decline (coefficient = -0.03 dB/year; 95% confidence interval, -0.04 to -0.01). Event-based and trend-based analyses found no significant associations for macular DVD with the likelihood/rate of past VF progression (P > .05).

CONCLUSIONS

Lower macular SVD, and not DVD, was associated with a higher probability of past VF progression. Macular optical coherence tomography angiography imaging shows promise for identifying eyes at risk of VF progression in patients with glaucoma.

Attenuated Amplitude of Pattern Electroretinogram in Glaucoma Patients with Choroidal Parapapillary Microvasculature Dropout

This study aims to investigate whether parapapillary choroidal microvasculature dropout (MvD) is related to visual function measured by pattern electroretinogram (PERG) in glaucomatous eyes with β-zone parapapillary atrophy (PPA). A total of 79 patients with open angle glaucoma and preperimetric glaucoma with β-zone PPA was included in this cross-sectional study. Through the deep layer of the Swept-source optical coherence tomography angiography image, the angular width and the area of MvD were measured. Visual function was evaluated with a standard automated perimetry and PERG. N95 and P50 PERG amplitudes in eyes with MvD were noticeably decreased compared to those without MvD (p = 0.004 and p = 0.007, respectively), although the mean deviation was not significantly different (p = 0.107). The lower N95 amplitude was associated with the presence of MvD (β = −0.668, p = 0.017) and wider angular width of MvD (B = −7.612, p = 0.014). Old age (p = 0.001), average ganglion cell’s inner plexiform layer thickness (p = 0.003), and the presence of MvD (p = 0.020) were significantly related to low N95 amplitude. Association between the presence and extent of the MvD and PERG amplitudes suggests that the presence of MvD has relevance to the generalized dysfunction of retinal ganglion cells.

Optic Disc Microvasculature Dropout in Glaucoma Detected by Swept-Source Optical Coherence Tomography Angiography

PURPOSE

To assess the clinical utility of swept-source optical coherence tomography angiography (SS-OCTA) in detecting optic disc microvasculature dropout (MvD-D) in primary open-angle glaucoma (POAG) eyes.

DESIGN

Cross-sectional study.

METHODS

The study enrolled 197 eyes of 197 patients with POAG with acceptable-quality SS-OCTA (PLEX Elite 9000; Carl Zeiss Meditec) images. A whole-signal-mode 6.0- × 6.0-mm optic disc cube was obtained with projection artifact removal. Three groups were categorized: no MvD-D (group 1), MvD-D (group 2, complete loss of microvasculature within the optic disc), and indiscernible MvD-D (group 3, poor visualization of the anterior lamina cribrosa [LC]).

RESULTS

There were 82 (42.1%) and 81 (41.5%) eyes categorized as no MvD-D (group 1) and MvD-D (group 2), respectively. The remaining 32 eyes (16.4%), categorized as indiscernible MvD-D (group 3), had a significantly smaller anterior scleral canal opening (ASCO) area (P < .05). Group 2 had significantly worse visual field (VF) mean deviation (MD), thinner average retinal nerve fiber layer (RNFL), higher prevalence of focal LC defect, and parapapillary deep-layer microvasculature dropout (MvD-P) than the other 2 groups (P < .05). In the multivariable logistic regression analysis, higher prevalence of focal LC defect (odds ratio, 46.91; P < .001) and MvD-P (odds ratio, 48.94; P < .001) remained as factors associated with MvD-D.

CONCLUSIONS

The presence of MvD-D could be well determined by SS-OCTA in eyes with POAG. MvD-P and focal LC defects were strongly associated with MvD-D. This suggests that SS-OCTA can serve as a useful tool in detecting optic disc microvasculature damage.

Association of choroidal blood flow with autonomic dysfunction in patients with normal tension glaucoma

There is increasing evidence that autonomic dysfunction is an important factor in the progression of glaucoma. Mechanism of the association between autonomic dysfunction and progression of glaucoma is poorly understood. Since blood circulation is basically regulated by the autonomic nervous system, autonomic dysfunction may contribute to unstable or fluctuating blood pressure. Therefore, It is hypothesized that autonomic dysfunction may contribute to impaired ocular blood flow and lead to glaucoma progression. However, no clinical study yet has evaluated the relationship between ocular blood flow and autonomic nervous function. We enrolled 152 open angle glaucoma patient. Ocular blood flow was assessed by measuring vessel density (VD) using optical coherence tomography angiography, and autonomic nervous function was evaluated with heart-rate variability (HRV) parameters. The low frequency/high frequency (LF/HF) ratio, which is one of the HRV parameters, quantified the degree of sympathovagal balance. This indicator could represent autonomic dysfunction. Higher LF/HF ratio was associated with reduction of the deep parapapillary VD (R =  − 0.243, P = 0.003). Linear regression analysis showed a significant negative association between parapapillary choroidal VD and LF/HF ratio (β =  − 0.249; 95% confidential interval =  − 1.193 to − 0.249; P = 0.002) in multivariate analysis. We demonstarted the association between impaired ocular blood flow (parapapillary choroidal vessel density) and autonomic dysfunction (LF/HF ratio). This study could help understand the role of the autonomic dysfunction in pathophysiology of glaucoma progression.

Parapapillary deep-layer microvasculature dropout is only found near the retinal nerve fibre layer defect location in open-angle glaucoma

PURPOSE

We aimed to investigate the topographic correspondence between deep-layer microvasculature dropout (MvD) and retinal nerve fibre layer (RNFL) defects in eyes with open-angle glaucoma (OAG) using spectral-domain optical coherence tomography (SD-OCT) and optical coherence tomography angiography (OCT-A).

METHODS

Microvasculature dropout width and location were determined using OCT-A, RNFL thickness, RNFL defect width and location were revealed using SD-OCT. The association between MvD and RNFL widths and that between the location of the MvD and RNFL defects were investigated. In addition, patients with OAG were divided into two groups: the RNFL defect in one hemiretina (RNFLD-HR) group (n = 24 eyes) and the RNFL defects in both hemiretinas (RNFLD-BR) group (n = 25 eyes). The presence, width and location of MvDs were compared between the two groups.

RESULTS

Forty-nine eyes were included. In 24 RNFLD-HR eyes, all MvDs were found in the inferior area, corresponding with the location of the RNFL defect. Meanwhile, in 25 RNFLD-BR eyes, 18 MvDs (72%) were found in the inferior hemiretina, two (8%) were found in the superior hemiretina, and five (20%) were found in both hemiretinas. In RNFLD-BR eyes, the average RNFL thickness was thinner in a location with MvD than a location without MvD.

CONCLUSION

Considering that MvD is only observed at the location of the RNFL defect in RNFLD-HR eyes and is usually found in the location of more severe RNFL defects in RNFLD-BR eyes, MvD seems to be a sign that accompanies glaucomatous damage in OAG eyes.

Relationship of macular ganglion cell complex thickness to choroidal microvasculature drop-out in primary open-angle glaucoma

BACKGROUND/AIMS

To investigate the rate of ganglion cell complex (GCC) thinning in primary open-angle glaucoma (POAG) patients with and without deep-layer microvasculature drop-out (MvD).

METHODS

POAG patients who had at least 1.5 years of follow-up and a minimum of three visits were included from the Diagnostic Innovations in Glaucoma Study. MvD was detected at baseline by optical coherence tomography angiography (OCT-A). Area and angular circumference of MvD were evaluated on en face choroidal vessel density images and horizontal B-scans. Rates of global and hemisphere GCC thinning were compared in MvD and non-MvD eyes using linear mixed-effects models.

RESULTS

Thirty-six eyes with MvD and 37 eyes without MvD of 63 patients were followed for a mean of 3.3 years. In 30 out of 36 eyes, MvD was localised in the inferotemporal region. While mean baseline visual field mean deviation was similar between the two groups (p=0.128), global GCC thinning was significantly faster in eyes with MvD than in those without MvD (mean differences: -0.50 (95% CI -0.83 to -0.17) µm/year; p=0.003)). Presence of MvD, area and angular circumference of MvD were independently associated with a faster rate of thinning (p=0.002, p=0.031 and p=0.013, respectively).

CONCLUSION

In POAG eyes, GCC thinning is faster in eyes with MvD. Detection of MvD in OCT-A images can assist clinicians to identify patients who are at higher risk for central macula thinning and glaucomatous progression and may require more intensive management.

[Choroidal microvascular dropout as a biomarker of glaucoma progression in patients with diabetes mellitus]

PURPOSE

To study the occurrence, features of the development of choroidal microvascular dropout (CMvD) as a possible marker of the severity of the glaucoma process and to assess the impact of diabetes mellitus (DM) on the progression of these changes.

MATERIAL AND METHODS

The study included 258 eyes (258 patients), which were divided into groups: 1st - 58 patients (58 eyes) with stage I POAG and DM; 2nd - 50 patients (50 eyes) with stage I POAG; 3rd - 50 patients (50 eyes) with stage III POAG and DM; 4th - 50 patients (50 eyes) with stage III POAG; 5th - 50 patients (50 eyes) with DM. The observation period lasted 24 months. The occurrence and dynamics of the development of CMvD, their relationship with structural and functional indicators of the optic disc in the course of observation were evaluated in patients with POAG and DM.

RESULTS

CMvD was detected in stage I POAG in 17 eyes (34%), in patients with DM - in 27 eyes (54%), in the combined course of stage I POAG and DM - in 46 eyes (79.31%), in patients with stage III glaucoma - in 100% of cases. In patients with stage III glaucoma, the CMvD area indicators exceeded the values in other groups and practically did not differ regardless the presence of DM (0.59±0.13 mm², p=0.005) and its absence (0.57±0.14 mm², p=0.005). In the first year of follow-up, the increase in the area size of microvascular disorders in patients with POAG I was 5.88%, in comorbid patients - 3.84%, but by the end of the follow-up it increased by 19.23%, and in the group of patients with a high rate of progression - by 31.25%. Strong reliable correlations of CMvD with mean deviation (r=0.89) were revealed, as well as moderate correlations - with structural indicators of the optic disc (r=0.59) and with hemodynamic indicators (r=0.54 and r=0.52).

CONCLUSION

Development of CMvD is both a result of glaucomatous damage to the optic nerve and a consequence of a disruption of its hemodynamics at the level of the deep capillary plexus. The results of the study demonstrate the adverse effect of DM on the course of glaucoma, which determines the initiation of microvascular disorders that aggravate the severity of the glaucoma process and the rate of its progression.

Associations Between the Choroidal Vascularity Index and Malignant Glaucoma After Trabeculectomy for Primary Angle Closure Glaucoma

Purpose: To compare the choroidal vasculature characteristics by using the choroidal vascularity index (CVI) in eyes with malignant glaucoma (MG), fellow eyes with non-MG, and eyes with uncomplicated primary angle-closure glaucoma (PACG) after trabeculectomy by spectral-domain optical coherence tomography (SD-OCT). Methods: This case-control study included 53 patients diagnosed with MG after trabeculectomy. Eyes with MG (n = 53) and the fellow eyes with non-MG (n = 50) were included. Eyes with PACG without MG after trabeculectomy (n = 60) were also enrolled as controls. The choroidal parameters, including CVI and the subfoveal choroidal thickness (SFCT), were measured by using SD-OCT images. Results: Eyes with MG and the fellow eyes showed a significantly lower CVI than eyes with PACG controls (p < 0.001). After adjusting for age, sex, axial length (AL), and intraocular pressure (IOP), eyes with the greater CVI [odds ratio (OR), 0.44] were significantly related to MG. The area under the receiver operating characteristic curve of the CVI was greater than that of the SFCT in the diagnosis of MG (0.911 vs. 0.840, p = 0.034). Conclusion: Eyes with MG showed a significantly lower macular CVI than eyes with PACG controls. A higher macular CVI was an associated factor of eyes with MG. The CVI serves as a more stable and sensitive indicator for MG than the SFCT in this group of patients with PACG.

Combined wide-field optical coherence tomography angiography density map for high myopic glaucoma detection

The present study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (OCTA) density map for detection of glaucomatous damage in high myopic (HM) eyes and to further compare the diagnostic ability of OCTA with that of conventional imaging approaches including red-free photography and swept-source OCT (SS-OCT) wide-field maps. A total of 77 healthy HM eyes and 72 HM eyes with open angle glaucoma (OAG) participated in this retrospective observational study. Patients underwent a comprehensive ocular examination, including wide-field SS-OCT scan and peripapillary area and macular OCTA scans. An integrated OCTA density map thereafter was merged by vascular landmark-guided superimposition of peripapillary and macular superficial vascular density maps onto the red-free photography (resulting in the OCTA-PanoMap). Glaucoma specialists then determined the presence of glaucomatous damage in HM eyes by reading the OCTA-PanoMap and compared its sensitivity and specificity with those of conventional images. Sensitivity and specificity of OCTA-PanoMap for HM-OAG diagnosis was 94.4% and 96.1%, respectively. Compared with other imaging methods, the sensitivity of OCTA-PanoMap was significantly higher than that of red-free photography (P = 0.022) and comparable to that of wide-field SS-OCT maps. Specificity of OCTA-PanoMap was significantly higher than those of other conventional imaging methods (except for wide-field thickness map). The OCTA-PanoMap showed good diagnostic ability for discrimination of HM-OAG eyes from healthy HM eyes. As a complementary method of an alternative imaging modality, OCTA-PanoMap can be a useful tool for detection of HM-OAG.

Clinical characteristics of choroidal microvasculature dropout in normal-tension glaucoma versus nonarteritic anterior ischemic optic neuropathy: an optical coherence tomography angiography study

The present study investigated the characteristics of choroidal microvasculature dropout (CMvD) in eyes with nonarteritic anterior ischemic optic neuropathy (NAION) versus those in eyes with normal-tension glaucoma (NTG). This study included 27 NAION, 27 NTG, and 27 healthy control subjects. CMvD was observed in 15 eyes (55.6%) of the NAION group and 20 (74.1%) of the NTG group. The area and angular width of CMvD were significantly greater in eyes with NAION (0.278 ± 0.172 mm² and 86.5 ± 42.3°) than in those with NTG (0.138 ± 0.068 mm² and 35.1 ± 16.2°, p = 0.002 and p < 0.001, respectively). CMvD in eyes with NAION were distributed in 120–250° and most frequently located at the temporal region, while CMvD in eyes with NTG showed double peaks at 220–280° and 110–140° and most frequently located at the inferotemporal region. The factors associated with the discrimination of NAION from NTG were greater area of CMvD (OR, 1.181; 95% CI, 1.021–1.366; p = 0.025) and location closer to the temporal region of the CMvD (OR, 0.904; 95% CI, 0.838–0.975; p = 0.009). The clinical characteristics of CMvD differed between eyes with NAION and those with NTG. Optical coherence tomography angiography may provide an additional approach to differentiating glaucoma from NAION.

Comparative Topographical Analysis of Choroidal Microvascular Dropout Between Glaucoma and Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose

To identify the presence of choroidal microvascular dropout (MvD) in nonarteritic anterior ischemic optic neuropathy (NAION) eyes and to characterize the topographical distribution for the mechanistic interpretation of MvD development.

Methods

We performed optical coherence tomography angiography on 47 open-angle glaucoma (OAG) and 19 NAION eyes with β-zone peripapillary atrophy (βPPA). We recorded the presence of MvD and compared between the peripapillary topographical measures of MvD, retinal nerve fiber layer (RNFL) defect, and βPPA in angular width and location.

Results

MvD was present in both diseases, marginally more frequently in NAION eyes (19/19, 100.0%) than in OAG eyes (38/47, 80.6%, P = 0.050), without a discernable difference in appearance. NAION eyes also showed wider MvD and RNFL defects compared to OAG eyes (both P < 0.001). In topographical measurements, the distribution of MvD showed a strong correspondence to superimposition areas of βPPA and RNFL defects, more distinctly than to RNFL defects (all P < 0.001). The outline of superimposition area also remarkably resembled the MvD area.

Conclusions

MvD was present in both the OAG and NAION groups. The βPPA-RNFL defect superimposition area topographically and morphologically matched MvD. Further investigations are needed to elucidate the role of RNFL defects in the pathogenesis of MvD and the clinical significance.

Progression of Parapapillary Choroidal Microvascular Dropout After Disc Hemorrhage in Glaucoma Patients: 2 Case Reports

PURPOSE

Microvasculature dropout (MvD) is a novel finding seen in optical coherence tomography angiography (OCTA), which is characterized by a localized dehiscence of the choriocapillaris in the parapapillary atrophy area. Disc hemorrhage (DH) is an important factor often associated with the development and especially progression of glaucoma. Here, we present 2 cases of MvD progression with DH.

METHODS AND RESULTS

Case 1: A 62-year-old female patient with normal tension glaucoma in both her eyes had recurrent DH at the inferior area of her right eye. A new DH was observed in the inferotemporal area of the right eye with MvD progression on OCTA in the same direction three months from the baseline.Case 2: A 57-year-old female patient with bilateral steroid-induced secondary glaucoma also had recurrent DH in her right eye. Four months from the baseline, DH occurred in the superotemporal and inferotemporal area of the right eye, and MvD was detected on OCTA in the superotemporal corresponding direction. After 19 months from the baseline, OCTA was repeated. The DH had resolved, but the superotemporal MvD persisted.

CONCLUSIONS

The 2 cases presented here are the first to report on the relationship between MvD progression and DH. MvD as visualized in OCTA imaging looks to be of clinical importance, and hopefully future studies will reveal the actual connection between MvD, DH, and glaucoma progression.

Baseline Choroidal Microvasculature Dropout as a Predictor of Subsequent Visual Field Progression in Open-angle Glaucoma

PRECIS

Choroidal microvasculature dropout (CMvD) is an independent predictor for overall and central visual field (VF) progression in open-angle glaucoma (OAG) eyes.

PURPOSE

The purpose of this study was to investigate the impact of CMvD identified by optical coherence tomography angiography (OCT-A) at baseline on subsequent VF progression in eyes with OAG.

METHODS

This retrospective observational study included 80 OAG eyes with CMvD [CMvD(+)] and without CMvD [(CMvD(-)] at baseline [40 of each matched for both age (10 y and below) and baseline VF severity (≤1 dB)]. The patients were followed regularly at 6-month intervals. VF progression was defined according to the Early Manifest Glaucoma Trial criteria. Associations of overall VF progression with baseline clinical factors, including the presence of CMvD and other variables, were analyzed by logistic regression with a generalized estimating equation in the entire OAG cohort. Linear mixed models were used to determine the differences in visual field mean sensitivity (VFMS) between the CMvD(+) and CMvD(-) groups globally and regionally at each follow-up point.

RESULTS

During a mean follow-up of 35.91±2.51 months, a significant difference was evident in the VF progression rate between the CMvD(-) and CMvD(+) groups (22.5% vs. 70%, P<0.001). CMvD at baseline and a higher visit-to-visit intraocular pressure fluctuation were significant predictors of VF progression. The VFMS differed significantly between the 2 groups at the central and superior central VF regions after 2 years of follow-up.

CONCLUSION

The presence of CMvD at baseline is an independent predictor of subsequent VF progression. CMvD(+) eyes show a faster rate of VFMS loss at the central and superior central VF regions.

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. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Juxtapapillary Deep-Layer Microvasculature Dropout and Retinal Nerve Fiber Layer Thinning in Glaucoma

PURPOSE

We sought to characterize juxtapapillary (JP) and non-JP microvasculature dropout in patients with primary open-angle glaucoma and to compare their rate of retinal nerve fiber layer (RNFL) thinning.

DESIGN

Retrospective cohort study.

METHODS

A total of 141 eyes with primary open-angle glaucoma with ≥4 serial optical coherence tomography (OCT) images after initial OCT angiography for ≥2 years were included. Based on OCT angiography imaging, the 3 groups were matched by age and visual field mean deviation: JP group (parapapillary deep-layer microvasculature dropout in contact with the optic disc boundary, n = 47), non-JP group (dropout not reaching the optic disc boundary, n = 47), and no-dropout group (lacking the dropout, n = 47). The RNFL thinning rate was compared among the 3 groups.

RESULTS

The rate of RNFL thinning tended to be fastest in the JP group followed by the non-JP group and no-dropout group in all areas except the temporal and nasal sectors. Post hoc analysis revealed that the JP group had significantly faster RNFL thinning than did the no-dropout group in the global area and the inferotemporal and inferonasal sectors (P < .05). When subgroup analysis was performed for subjects in which the main sector of dropout was the inferotemporal sector, the JP group had significantly faster RNFL thinning than the other 2 groups in the corresponding inferotemporal sector (P < .001).

CONCLUSION

Eyes with JP microvasculature dropout showed faster RNFL thinning than eyes without dropout. These findings suggest that deep-layer microvasculature dropout, especially in contact with the optic disc boundary, is associated with rapid glaucoma progression.

An Increased Choroidal Microvasculature Dropout Size is Associated With Progressive Visual Field Loss in Open-Angle Glaucoma

PURPOSE

To investigate whether the choroidal microvasculature dropout (CMvD) increases in size over time among open-angle glaucoma (OAG) eyes presenting with CMvD at baseline and evaluate the association between longitudinal CMvD size increases and subsequent visual field (VF) progression.

DESIGN

Retrospective cohort study.

METHODS

This study enrolled 101 eyes from 101 consecutive patients with OAG with a localized CMvD and glaucomatous VF defects at baseline and a minimum 2-year follow-up. The angular circumference (AC) of the CMvD was determined from choroidal layer images using optical coherence tomography angiography at the baseline and final follow-up. Demographic and ocular characteristics, including the rate of retinal nerve fiber layer thickness loss and amount of CMvD AC increase during follow-up, were compared between OAG eyes with and without VF progression. Cox proportional hazard analysis was performed to identify the clinical factors associated with VF progression. The relationships between CMvD angular enlargement during follow-up and clinical factors were assessed.

RESULTS

CMvD angular enlargement was found in 21.8% of patients while VF progression was observed in 26.7% of the OAG eyes with CMvD during a mean 2.52-year follow-up. OAG eyes with VF progression showed a significantly greater CMvD angular enlargement. A larger increase in the CMvD AC was an independent predictor of VF progression. CMvD AC changes were significantly correlated with the rates of VF deterioration.

CONCLUSIONS

VF progression is significantly associated with a greater longitudinal increase in the CMvD AC in OAG eyes with CMvD. CMvD AC changes have significant correlations with the rate of VF loss.

Parapapillary Intrachoroidal Cavitation in Glaucoma: Association with Choroidal Microvasculature Dropout

PURPOSE

To characterize the choroidal microvasculature in glaucomatous eyes with parapapillary intrachoroidal cavitation (PICC) using optical coherence tomography angiography (OCTA) and its association with parapapillary choroidal microvasculature dropout (MvD).

METHODS

This study included 47 glaucomatous eyes with PICC, as identified by color fundus photography and optical coherence tomography scanning of the optic nerve head area. Peripapillary choroidal microvasculature was evaluated on en-face OCTA images. Choroidal MvD was defined as a focal sectoral capillary dropout with no visible microvascular network.

RESULTS

PICC was visible as a well-demarcated area with homogeneously reduced vessel density in en-face OCTA images of the choroidal layer. MvD was detected in 42 eyes (89.4%). Although located in the juxtapapillary area adjacent to the PICC, MvD was confined to the area of parapapillary atrophy. MvD observed in OCTA en-face images was distinguished from the area of PICC by the absence of vascular signal. Of the 50 PICCs, 49 (98.0%) had hemifield visual field defects at the location corresponding to the hemispheric location of PICC.

CONCLUSIONS

PICC was found to have a characteristic microvascular feature in choroidal en-face OCTA images, and to be topographically associated with glaucomatous visual field defect. PICC was frequently accompanied by MvD and was located adjacent to the area of MvD, suggesting that PICC and MvD have similar pathogenesis.

OCT-angiography detects longitudinal microvascular changes in glaucoma: a systematic review

BACKGROUND/AIMS

Optical coherence tomography angiography (OCTA) allows the study of vessel density (VD). We intended to perform a systematic review of studies focusing on longitudinal changes in peripapillary and macular VD measurements in glaucoma.

METHODS

A search was performed across MEDLINE, Scopus, ISI Web of Science and Google Scholar, using the following query from inception until 20 September 2019: (("optical coherence tomography angiography"[tiab]) OR (optical coherence tomography angiography[MeSH]) OR ("OCTA"[tiab]) OR ("OCT-A"[tiab]) OR ("angio-OCT"[tiab]) OR ("OCT- angiography"[tiab]) OR ("OCT-angio"[tiab]) OR ("OCT-angiographie"[tiab])) AND (glaucom*[tiab] OR glaucoma[MeSH]). Prospective studies that quantitatively assessed the longitudinal changes in VD in glaucoma with at least 3 months of follow-up were included.

RESULTS

Ten out of 4516 studies were included. The rate of VD change in glaucoma varied from 0.036/year to 1.08/year and 1.3% to 3.2% per year, with significantly different rates between glaucoma and healthy controls. Five studies assessed VD change after glaucoma surgery, obtaining variable results, ranging from a temporary VD decrease to increase after 3 months. Meta-analysis was not possible due to a wide variation in methods, measurements and region of VD.

CONCLUSION

OCTA is a non-invasive technology, which shows promise in glaucoma. Measures should be taken to increase the quality and standardise the methodology of VD measures in OCTA longitudinal studies, for future meta-analyses.

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.

Progressive retinal nerve fibre layer thinning and choroidal microvasculature dropout at the location of disc haemorrhage in glaucoma

BACKGROUND/AIMS

To investigate whether parapapillary choroidal microvasculature dropout (MvD) is associated with progressive retinal nerve fibre layer (RNFL) thinning in eyes with primary open-angle glaucoma (POAG) and disc haemorrhage (DH).

METHODS

Parapapillary microvasculature was evaluated by swept-source optical coherence tomography (OCT) angiography (OCTA) in 50 eyes with POAG and DH, 1 year before, at the time of and 1 year after the detection of DH. MvD was defined as an area in the parapapillary deep layer of focal sectoral dropout with no visible microvascular network. Progressive changes in OCT RNFL thickness were compared in groups of eyes with and without MvD.

RESULTS

Cumulative prevalence of MvD was 76.0% (38 eyes) at 1 year after detection of DH. All MvDs were detected in the same sectoral locations as DH. In eyes with MvD, global RNFL thickness and sectoral RNFL thickness at the location of DH were significantly reduced, both from 1 year before to the time of DH detection (both p<0.001) and from DH detection to 1 year later (both p<0.001). In eyes without MvD, however, the reductions in global (p=0.011) and sectoral (p=0.007) RNFL thickness were significant only from DH detection to 1 year later.

CONCLUSION

In eyes with POAG, RNFL thinning was spatially consistent and progressive at the location of MvD accompanied by subsequent DH and continued to progress after the occurrence of DH. When DH was not accompanied by MvD, progressive RNFL thinning was more likely to occur after the detection of DH.