Reproducibility of Optical Coherence Tomography Angiography Macular and Optic Nerve Head Vascular Density in Glaucoma and Healthy Eyes

Comparison of quantitative measurement of macular vessel density before and after inferior oblique muscle-weakening surgery: An optical coherence tomography angiography study

PURPOSE

To investigate hemodynamic changes in retinal and choroidal vasculature after surgical inferior oblique (IO) weakening through optical coherence tomography angiography (OCTA).

METHODS

The medical records of patients who underwent unilateral IO-weakening surgery at a single institution were retrospectively reviewed. Patients who had OCTA measurements before surgery and on postoperative days 7 and 30 were included. Vessel density was determined for the superficial capillary plexus (SCP), deep capillary plexus (DCP), the choriocapillaris (CCP) and the foveal avascular zone (FAZ).

RESULTS

The study included 72 eyes of 36 patients. Fellow eyes were used as a control group. The preoperative and postoperative week 1 and month 1 mean central vessel densities of the SCP were 20.48% ± 3.52%, 20.68% ± 3.83%, and 23.56% ± 5.65%, respectively, in the operated eye; those of the DCP were 16.72% ± 3.33%, 16.08% ± 4.65%, and 20.85% ± 7.09%, respectively. The mean FAZ areas were 341.29 ± 88.04 μm², 341.30 ± 98.25 μm², and 316.02 ± 74.61 μm², respectively. We detected no significant changes in SCP, DCP, and FAZ in the postoperative period. The mean central vessel density of the CCP increased significantly from the preoperative level of 54.06% ± 2.86% to 55.55% ± 2.63% at postoperative week 1, but there was no significant difference between baseline and postoperative month 1 (P = 0.001 and P = 0.515, resp.).

CONCLUSIONS

IO muscle surgery does not seem to cause alterations in retinal hemodynamics, although it can transiently increase the central vessel density of the CCP during the early postoperative period.

Investigation of progression pattern and associated risk factors in glaucoma patients with initial paracentral scotomas using Humphrey 10-2

Central visual field (VF) progression could directly threaten patientss visual function compared to glaucomatous damage. This study was designed to investigate visual field (VF) progression pattern and associated risk factors including optical coherence topography angiographic (OCT-A) findings in glaucoma patients with initial paracentral scotoma. This prospective, observational study included 122 eyes presenting as initial paracentral scotomas with serial 24-2 and 10-2 VF tests at the glaucoma clinic of Seoul St Mary's Hospital between November 2017 and August 2020. The participants underwent at least 5 serial VF exams and OCT-A at baseline. Numerical values of the initial and final 10-2 VF tests were averaged for each VF test point using the total deviation map. Innermost 10-2 VF progression was defined as three or more new contiguous points at the central 12 points on 10-2 VF. Other clinical characteristics were collected including history of disc hemorrhage and vessel density (VD) was measured from OCT-A images. Linear regression analysis was performed to obtain the change of mean deviation and a cut-off for progression was defined for both 24-2 and 10-2 VFs. The average total deviation maps of the initial 10-2 VF tests shows initial paracentral scotoma located in the superior region in an arcuate pattern that was deep in the 4°–6° region above fixation. This arcuate pattern was more broadly located in the 4°–10° region in the primary open-angle glaucoma (POAG) group, while it was closer to fixation in 0°–4° region in the normal-tension glaucoma (NTG) group. The final average map shows deepening of scotomas in the 4°–10° region in POAG, which deepened closer to the region of fixation in NTG. The diagnosis of NTG (β 1.892; 95% CI 1.225–2.516; P = 0.035) and lower choroidal VD in the peripapillary atrophy (PPA) region (β 0.985; 95% CI 0.975 to 0.995; P = 0.022) were significantly related to innermost 10-2 VF progression. Initial paracentral scotomas in NTG tended to progress closer to the region of fixation, which should be monitored closely. Important progression risk factors related to paracentral scotoma near the fixation were the diagnosis of NTG and reduced choroidal VD in the β-zone PPA region using OCT-A. We should consider vascular risk factors in NTG patients presenting with initial paracentral scotoma to avoid vision threatening progression of glaucoma.

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.

Diurnal Variation of Retinal Vessel Density in Healthy Human Eyes

PRECIS

A small increase in optic nerve head vessel density (VD), but not macular VD, in the evening compared with the morning is observed in healthy subjects.

PURPOSE

To evaluate the diurnal variation of the macular and optic nerve head (ONH) VD in healthy eyes as measured with optical coherence tomography angiography (OCT-A).

METHODS

In this prospective study of healthy individuals older than 18 years old, VD parameters, including macular whole image vessel density, parafoveal vessel density, ONH whole image vessel density, ONH whole image capillary density, circumpapillary vessel density (cpVD), and circumpapillary capillary density, were measured with OCT-A at 4 time points throughout the day (8 am, 12 pm, 4 pm, and 8 pm).

RESULTS

Twenty-nine healthy eyes were included from 15 subjects (mean age: 30.9 y). After adjustment for age and mean ocular perfusion pressure, a significant positive rate of change was found for cpVD (0.05%/h; P=0.027). In contrast, macular VD changes were not significantly different. When comparing morning (8 am and 12 pm) and evening (4 pm and 8 pm) measurements, there were small, but statistically significant, increases for all ONH measurements. The greatest increase was found for cpVD (0.58%; P=0.022). Significant but small increases in mean arterial pressure and mean ocular perfusion pressure were also observed.

CONCLUSIONS

There was a small increase in ONH VD, but not macular VD, in the evening compared with the morning in healthy human eyes. As the observed difference was within the measurement variability, our results suggest the timing of OCT-A examination does not affect retinal VD measurements.

Assessment of retinal microvascular health by optical coherence tomography angiography among persons with HIV

Microvasculopathy may link HIV-related chronic inflammation and premature multimorbidity. In this proof-of-concept study, we used optical coherence tomography angiography (OCTA) to evaluate the retina as a convenient assessment of microvascular health among persons with HIV (PWH) undergoing surveillance ophthalmic care at Emory from 2018 to 2021. Among patients with longstanding HIV, OCTA identified microvascular abnormalities even among eyes without clinical retinal disease. Retinovascular evaluation by OCTA is a feasible, noninvasive technique for assessing microvasculopathy among PWH.

Repeatability of Manual Measurement of Foveal Avascular Zone Area in Optical Coherence Tomography Angiography Images in High Myopia

PURPOSE

To analyze the repeatability of manual measurement of foveal avascular zone (FAZ) area in an optical coherence tomography angiography (OCTA) image in high myopia.

METHODS

This study comprised patients with high myopia and controls. Two consecutive FAZ areas of the superficial and deep capillary plexus were obtained using OCTA. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were assessed, and univariate and multivariate generalized linear mixed models were conducted to identify factors related to repeatability.

RESULTS

Thirty eyes with high myopia and 34 eyes of healthy subjects were included in the study. The mean age in high myopia and control subjects was 55.5 and 60.8 years, respectively, the mean spherical equivalent was -9.98 and -0.55 diopters, and the mean axial length was 28.0 and 23.9 mm. The ICCs of FAZ area of the superficial capillary plexus (SCP) were 0.891 and 0.919, while the CVs were 8.8% and 8.5%. In measurement of the deep capillary plexus, the ICCs were 0.788 and 0.907, while the CVs were 11.2% and 11.0%, which were acceptable but exhibited lower repeatability than those of SCP. Multivariate analyses showed that older age (p = 0.030) and greater axial length (p = 0.005) were significantly associated with lower repeatability of SCP FAZ area measurements. In addition, greater axial length (p = 0.044) was a significant factor for lower repeatability of deep capillary plexus FAZ area measurements.

CONCLUSIONS

Manual measurement of FAZ area using OCTA exhibited relatively good repeatability for high myopia. Age and axial length affected repeatability and should be considered when analyzing FAZ areas in high myopia patients.

Erlanger Glaucoma Registry: Effect of a Long-Term Therapy with Statins and Acetyl Salicylic Acid on Glaucoma Conversion and Progression

Purpose: Drugs with cardiovascular protective properties (statins, acetylsalicylic acid (ASS)) were assumed to have positive effects on patients suffering from glaucoma disease. The present retrospective study aimed to investigate the influence of statins, ASS or a combination of both on the glaucoma conversion and progression rate in glaucoma suspects and glaucoma patients with a 20-year follow-up period. Methods: A retrospective analysis of 199 eyes of 120 patients (63 male, 57 female) of the Erlanger Glaucoma Registry (EGR; ClinicalTrials.gov Identifier: NCT00494923; ISSN 2191-5008, CS-2011) was performed considering systemic therapy with statins, ASS or a combination of both: 107 eyes with ocular hypertension (OHT) and 92 eyes with pre-perimetric primary open-angle glaucoma (pre-POAG). All patients received an ophthalmological examination including morphometric and functional glaucoma diagnostics. Glaucoma conversion was defined as the conversion of OHT to pre-POAG. Glaucoma progression was defined as confirmed visual field loss. Data were shown as percentages. Statistical analysis was performed by Chi-Quadrat tests. Results: 1. Glaucoma conversion/progression was observed in 46.7% of the subjects, additionally in combination with hypercholesterinemia in 76.8%. 2. Statins: 27.3% of eyes under systemic statin therapy showed a conversion/progression. Patients taking statins ≥ 10 years yielded a reduced conversion/progression rate (p = 0.028, non-significant after Bonferroni-Holm). 3. ASS: 34.7% of eyes under systemic ASS therapy showed a conversion/progression. A significantly lower conversion/progression rate was observed after ASS therapy ≥ 12 years (p = 0.017, significant after Bonferroni-Holm). 4. ASS and statins: 25.0% of eyes under combined therapy showed a conversion/progression. A significantly reduced conversion/progression rate was reached after 8 years of combined therapy (p = 0.049, non-significant after Bonferroni-Holm). Conclusions: Patients with ocular hypertension and early glaucoma seem to benefit from adjuvant cardiovascular protective therapy. However, the benefits and disadvantages of treatment with statins and/or ASS should be kept in mind. Thus, a thorough risk-benefit evaluation has to be performed for each patient individually to avoid unwanted side effects.

Association Between Progressive Retinal Capillary Density Loss and Visual Field Progression in Open-Angle Glaucoma Patients According to Disease Stage

PURPOSE

To investigate the longitudinal changes in circumpapillary capillary density (cpCD) and retinal nerve fiber layer thickness (cpRNFLT) and their association with visual field (VF) progression in open-angle glaucoma (OAG) eyes at different stages of glaucoma.

DESIGN

Retrospective, observational case series METHODS: This study enrolled 158 eyes of 158 OAG patients classified into early (89 eyes) and moderate-to-advanced (69 eyes) stage based on VF mean deviation (MD; -6 dB). Serial cpCD and cpRNFLT measurements were performed using optical coherence tomography (OCT) angiography and OCT during a mean follow-up of 2.66 years. The reference standard of glaucoma progression was determined by VF progression. The rates of longitudinal change in cpCD and cpRNFLT were evaluated using linear mixed effects models and compared between progressors and nonprogressors. The factors associated with VF progression, including the rates of longitudinal change in cpCD and cpRNFLT, were assessed using logistic regression analyses.

RESULTS

The rate of longitudinal change in cpCD was significantly faster in progressors (-1.25% ± 1.15% per year for early stage and -1.61% ± 1.04% per year for moderate-to-advanced stage) than in nonprogressors (0.04% ± 1.12% per year for early stage and -0.34% ± 0.97% per year for moderate-to-advanced stage) regardless of glaucoma stage (all, P < .05). The rates of longitudinal change in cpRNFLT (-0.85 ± 1.20 µm/y vs -0.70 ± 1.02 µm/y, P = .396) did not differ between progressors and nonprogressors in eyes with moderate-to-advanced glaucoma. In multivariable logistic regression analyses, a faster rate of cpCD loss (odds ratio [OR] 0.244, P = .009) had a significant association with VF progression in eyes with moderate-to-advanced glaucoma, whereas faster rates of both cpCD (OR 0.340, P = .012) and cpRNFLT (OR 0.155, P = .031) loss were significantly associated with VF progression in eyes with early-stage glaucoma.

CONCLUSIONS

In OAG eyes, the rate of longitudinal cpCD loss was significantly associated with VF progression regardless of glaucoma stage.

Repeatability of Peripapillary Optical Coherence Tomography Angiography Parameters in Older Adults

Purpose:

This work assesses the intrasession repeatability of capillary perfusion density (CPD) and capillary flux index (CFI) measurements on peripapillary optical coherence tomography angiography (OCTA) in healthy eyes of older adults.

Methods:

In this cross-sectional study, healthy volunteers aged 50 years or older underwent 4.5 × 4.5 mm OCTA imaging centered on the optic nerve head using Zeiss Cirrus HD-5000 AngioPlex (Carl Zeiss Meditec). Two consecutive images were acquired in the same eye during a single study session. CPD and CFI were assessed using AngioPlex Software (version 11.0.0.29946) for the radial peripapillary capillary plexus (average over whole scan area) and 4 quadrants (superior, inferior, temporal, and nasal). CPD and CFI repeatability was assessed by intraclass correlation (ICC), mean interocular differences using 2-tailed t test, and association with age using generalized estimating equations.

Results:

A total of 150 images were acquired from 75 eyes of 47 patients. For CPD, ICC results ranged from 0.7160 (nasal CPD) to 0.9218 (average CPD). For CFI, ICC results ranged from 0.6167 (temporal CFI) to 0.8976 (inferior CFI). Temporal CFI was significantly different between right and left eyes of the same patient ( P = .03). CPD and CFI decreased with age in all analyses (average CPD β coefficient –0.00172, P < .001; average CFI β coefficient −0.00278, P < .001).

Conclusions:

Moderate to good repeatability was observed for most peripapillary OCTA metrics; temporal measurements were least repeatable for CPD and CFI. Peripapillary CPD and CFI decrease with age even beyond the fifth decade in healthy older adults.

Repeatability of Macular and Optic Nerve Head Measurements by Optical Coherence Tomography Angiography in Healthy Children

Aims: To evaluate the repeatability of the peripapillary and macular vascular parameters using optical coherence tomography angiography (OCT-A) in healthy children.Materials and methods: Cross-sectional study including 34 eyes of 34 healthy children. After a complete medical examination, two consecutive OCT-A exams were done using AngioPlex Cirrus 5000 (Carl Zeiss Meditec, Dublin, CA, USA) in the same session. The scan area used was 6 × 6 mm for the analysis of the superficial vascular plexus (SVP) in the macula, and 4.5 × 4.5 mm for the peripapillary plexus. To study the repeatability of the measurements, the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) of each pair of exams were calculated.Results: The mean age of the children included was 10.77 ± 2.49 years (range 6 to 15 years). Good and excellent ICCs were obtained for all the parameters considered. Peripapillary vascular parameters showed greater reproducibility than macular ones (global peripapillary perfusion density (pPD): ICC = 0.834 CV = 0.89% vs. whole macular area PD (w-mPD): ICC = 0.697 CV = 3.49%; global peripapillary flux index (FI): ICC = 0.858 CV = 1.28%; whole macular area vascular density (VD): ICC = 0.699 CV = 3.30%). Amongst the macular parameters, the characteristics of the foveal avascular zone (FAZ) were the ones showing higher rates of repeatability (FAZ circularity: ICC = 0.858 CV = 8.83%).Conclusion: OCT-A is a non-invasive, time-efficient technology that may be useful in the evaluation of the retinal and peripapillary vascular network in healthy children. The repeatability of the measures will allow the follow-up and evaluation of any change occurring in the macular or optic nerve perfusion.

Association of foveal avascular zone area withstructural and functional progression in glaucoma patients

BACKGROUND

To investigate whether quantitative optical coherence tomography angiography (OCTA) metrics of the superficial/deep macular retina and optic disc are associated with glaucoma progression risk.

METHODS

A total of 238 eyes from 119 patients with open angle glaucoma or ocular hypertension, and no history of systemic hypertension or diabetes mellitus were included. All participants underwent OCTA imaging with a swept-source OCT (DRI-OCT 1, Topcon, Japan). OCTA metrics of superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the macular region, and radial peripapillary capillary network of the optic disc were measured by a customised MATLAB program to obtain foveal avascular zone (FAZ) area, FAZ circularity and capillary density of SCP/DCP, and capillary density of the peripapillary region. Relationships between baseline OCTA metrics, visual field (VF) metrics, intraocular pressure fluctuation and risk of glaucoma progression were analysed with the Cox proportional hazards model. A frailty model was used to adjust for intereye correlation.

RESULTS

During a mean follow-up duration of 29.39 months (range 12-56 months), 50, 48 and 16 eyes were determined to have retinal nerve fibre layer (RNFL), ganglion cell-inner plexiform layer (GC-IPL) and VF progression respectively. FAZ area per SD increase at baseline were significantly associated with both RNFL thinning (HR 1.73 95% CI 1.04 to 2.90); p=0.036) and GC-IPL thinning (HR 2.62, 95% CI 1.59 to 4.31; p<0.001), after adjusting for age, axial length and other potential confounding factors. VF progression was associated with age (HR 1.05, 95% CI 1.02 to 1.08; p<0.001) and mean deviation value (HR 0.91, 95% CI 0.84 to 0.98; p=0.010), but not with any OCTA metrics.

CONCLUSION

Enlarged FAZ area measured by OCTA was associated with a higher risk of RNFL and GC-IPL thinning associated with glaucoma, but not with functional deterioration in glaucoma.

Analysis of the perfusion of the optic nerve using angio-OCT in glaucoma

The introduction of optical coherence tomography angiography (OCT-A) has generated interest in evaluating vascular dysfunctions in the optic nerve head for the diagnosis and monitoring of glaucoma. The purpose of this study is to compare perfusion of the optic disc between normal subjects and subjects with glaucoma using OCT-A in order to detect changes in perfusion of the optic disc. Using the OCT-A AngioVue® system, an examination was performed on 40 eyes of 40 patients (20 with glaucoma and 20 healthy controls). Total radial peripapillary flow density (4.5×4.5mm) was measured at different levels of segmentation. The study demonstrated that the peripapillary vascular flow of OCT-A and exploration of the optic nerve head was better in the normal eyes compared to glaucoma patients. This review provides a comprehensive summary of the most important current and potential applications of OCT-A in glaucoma.

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.

OCT Angiography for the Diagnosis of Glaucoma: A Report by the American Academy of Ophthalmology

PURPOSE

To review the current published literature on the use of OCT angiography (OCTA) to help detect changes associated with the diagnosis of primary open-angle glaucoma.

METHODS

Searches of the peer-reviewed literature were conducted in March 2018, June 2018, April 2019, December 2019, and June 2020 in the PubMed and Cochrane Library databases. Abstracts of 459 articles were examined to exclude reviews and non-English articles. After inclusion and exclusion criteria were applied, 75 articles were selected and the panel methodologist rated them for strength of evidence. Three articles were rated level I and 57 articles were rated level II. The 15 level III articles were excluded.

RESULTS

OCT angiography can detect decreased capillary vessel density within the peripapillary nerve fiber layer (level II) and macula (level I and II) in patients with suspected glaucoma, preperimetric glaucoma, and perimetric glaucoma. The degree of vessel density loss correlates significantly with glaucoma severity both overall and topographically (level II) as well as longitudinally (level I). For differentiating glaucomatous from healthy eyes, some studies found that peripapillary and macular vessel density measurements by OCTA show a diagnostic ability (area under the receiver operating characteristic curve) that is comparable with structural OCT retinal nerve fiber and ganglion cell thickness measurements, whereas other studies found that structural OCT measurements perform better. Choroidal or deep-layer microvasculature dropout as measured by OCTA is also associated with glaucoma damage (level I and II). Lower peripapillary and macular vessel density and choroidal microvasculature dropout are associated with faster rates of disease progression (level I and II).

CONCLUSIONS

Vessel density loss associated with glaucoma can be detected by OCTA. Peripapillary, macular, and choroidal vessel density parameters may complement visual field and structural OCT measurements in the diagnosis of glaucoma.

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 (OCTA) in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Vascular changes are increasingly recognized as important factors in the pathophysiology of neuroinflammatory disease, especially in multiple sclerosis (MS). The relatively novel technology of optical coherence tomography angiography (OCTA) images the retinal and choroidal vasculature non-invasively and in a depth-resolved manner. OCTA provides an alternative quantitative measure of retinal damage, by measuring vascular density instead of structural atrophy. Preliminary results suggest OCTA is sensitive to retinal damage in early disease stages, while also having less of a "floor-effect" compared with commonly used OCT metrics, meaning it can pick up further damage in a severely atrophied retina in later stages of disease. Furthermore, it may serve as a surrogate marker for vascular pathology in the central nervous system. Data to date consistently reveal lower densities of the retinal microvasculature in both MS and neuromyelitis optica spectrum disorder (NMOSD) compared with healthy controls, even in the absence of prior optic neuritis. Exploring the timing of vascular changes relative to structural atrophy may help answer important questions about the role of hypoperfusion in the pathophysiology of neuroinflammatory disease. Finally, qualitative characteristics of retinal microvasculature may help discriminate between different neuroinflammatory disorders. There are however still issues regarding image quality and development of standardized analysis methods before OCTA can be fully incorporated into clinical practice.

OCT angiography analysis of retinal vessel density in primary open-angle glaucoma with and without Tafluprost therapy

Background

Primary open-angle glaucoma (POAG) is a progressive neurodegenerative disease which leads to irreversible blindness. An elevated intraocular pressure (IOP) is considered to be the main risk factor for the disease progression. It is known that retinal blood flow is altered in POAG eyes. Tafluprost, a prostaglandin analogue which lowers the IOP, has shown to also improve the retinal blood flow in animals.

Methods

The current study therefore evaluated the retinal vessel density in the peripapillary and macular region of POAG patients with normal IOP treated with topical Tafluprost (n = 20) compared to surgically treated patients with normal IOP (n = 22) using optical coherence tomography angiography (OCT-A). The retinal flow density was obtained after binarisation and evaluated in five sectors.

Results

There was a significantly higher peripapillary flow density in all sectors in Tafluprost treated eyes when compared to post-surgery eyes. The flow density in the inferior sector of the superficial plexus in the macular region was also significantly higher in the Tafluprost group.

Conclusions: These results indicate that Tafluprost not only lowers IOP, but may also enhance retinal blood flow in POAG patients with a normal IOP.

Normative Data Assessment of Peripapillary and Macular Vessel Density and Foveal Avascular Zone Metrics Using Optical Coherence Tomography Angiography in Children

PURPOSE

To quantify the vessel density of the macula and optic disc and foveal avascular zone (FAZ) in healthy children and to evaluate the effects of age, gender, axial length, body mass index (BMI), and refractive errors on vessel density and FAZ.

METHODS

This study enrolled 92 eyes of 92 participants (42 boys and 50 girls). Optical coherence tomography angiography (OCTA) was performed using AngioVue (Avanti; Optivue). FAZ area, nonflow area, superficial and deep vessel density, FAZ perimeter, acircularity index of FAZ, foveal density, and radial peripapillary capillary vessel density were analyzed by gender. Correlations between the investigated OCTA parameters and age, axial length, and BMI were evaluated.

RESULTS

Girls had significantly larger nonflow and FAZ area than boys (P = .01 and .02). Superficial and deep vessel density at the fovea was significantly higher in boys compared to girls (P = .01 and .03). Inferior temporal and superior temporal Radial peripapillary capillary vessel densities were significantly higher in girls than boys (P = .01 and .03). No significant difference was found in the macular and optic disc vessel density measurements within refractive groups (P > .05, for all). Regarding the correlation of age with FAZ and vessel density parameters, only nonflow area was positively correlated with age (r = 0.22, P = .03).

CONCLUSIONS

This study provides normative data for children. Although boys had greater foveal vessel density, girls had greater FAZ area and nonflow area. Refractive status of the eye and BMI did not influence the OCTA parameters. Although nonflow area was positively correlated with age, other parameters were steady within the ages of 7 to 18 years. [J Pediatr Ophthalmol Strabismus. 2020;57(6):388-398.].

Impact of Pupil Dilation on Optical Coherence Tomography Angiography Retinal Microvasculature in Healthy Eyes

PRéCIS:: Small but significant decreases in optical coherence tomography angiography (OCTA)-measured circumpapillary capillary density (cpCD) were observed in healthy eyes dilated with 2.5% phenylephrine/0.5% tropicamide. Although likely clinically insignificant, ophthalmologists should consider these changes when interpreting OCTA results from dilated eyes.

PURPOSE

The purpose of this study was to investigate the effect of pupil dilation using 2.5% phenylephrine and 0.5% tropicamide on quantitative assessment of retinal microvasculature using OCTA.

METHODS

OptoVue AngioVue high density (HD) and non-HD OCTA macula and optic nerve head (ONH) images were obtained at 15-minute intervals predilation and postdilation in 26 healthy participants (mean age: 40.0; 95% confidence interval=33.9, 46.1 y). Superficial macular vessel density (VD) was measured in the whole image VD and the parafoveal region VD. ONH capillary density was measured in the whole image capillary density and the cpCD region. Differences between predilation and postdilation densities were assessed using linear mixed effects models to account for within-patient correlation.

RESULTS

Instillation of dilating drops resulted in a small but statistically significant reduction in non-HD ONH whole image capillary density of 0.6%, from a mean of 45.2% (95% confidence interval=41.9%, 48.4%) to 44.6% (41.4%, 47.8%) (P=0.046). A similar reduction in non-HD ONH cpCD of 0.8% also was observed, from a mean of 49.3% (45.3%, 53.3%) to 48.5% (44.5%, 52.4%) (P=0.025). No postdilation decreases in macular VD or HD ONH capillary density were observed.

CONCLUSIONS

Pupil dilation using topical 2.5% phenylephrine and 0.5% tropicamide results in a small but statistically significant reduction in non-HD ONH whole image and cpCD in healthy eyes. The observed reduction likely is not clinically significant because the observed reduction was within the previously reported range of measurement variability. Further studies should consider investigating these effects in nonhealthy eyes with glaucoma and media opacities, as well as older individuals.

Macular and peripapillary vessel density in myopic eyes of young Chinese adults

BACKGROUND

The aim of this study was to compare the macular and peripapillary vessel densities in eyes of young Chinese adults with different degrees of myopia and to evaluate the association of macular and peripapillary vessel densities with axial length and retinal nerve fibre layer thickness.

METHODS

A total of 128 eyes (mild myopia, 42; moderate myopia, 45; severe myopia, 41) underwent optical coherence tomography angiography imaging. Parameters assessed were vessel densities in the superficial capillary plexus and deep capillary plexus of the macular area, peripapillary vessel density, retinal nerve fibre layer thickness, foveal thickness and foveal avascular zone area (mm² ).

RESULTS

Vessel densities in the macular and peripapillary areas as well as peripapillary retinal nerve fibre layer thickness decreased significantly when comparing high myopia to mild myopia. Axial length was significantly associated with vessel density in the macular area (superficial capillary plexus: r = -0.249, p = 0.008; deep capillary plexus: r = -0.398, p < 0.001), peripapillary area (r = -0.204, p = 0.028), foveal avascular zone area (r = -0.309, p < 0.001), and foveal thickness (r = 0.354, p < 0.001). Negative correlations were found between axial length and peripapillary vessel density as well as retinal nerve fibre layer thickness at the nasal superior, nasal inferior and inferior nasal quadrants.

CONCLUSION

Varying degrees of myopia affected macular and peripapillary vessel densities as well as retinal nerve fibre layer thickness in young healthy adults. The high myopic group had the lowest vessel density in the superficial capillary plexus, deep capillary plexus of the macular area and the peripapillary area. With increased axial length, macular and peripapillary vessel densities, retinal nerve fibre layer thickness and foveal avascular zone area reduced while foveal thickness increased.

Vascular density with optical coherence tomography angiography and systemic biomarkers in low and high cardiovascular risk patients

We aimed to compare retinal vascular density in Optical Coherence Tomography Angiography (OCT-A) between patients hospitalized for acute coronary syndrome (ACS) and control patients and to investigate correlation with angiogenesis biomarkers. Patients hospitalized for an acute coronary syndrome (ACS) in the Intensive Care Unit were included in the "high cardiovascular risk" group while patients without cardiovascular risk presenting in the Ophthalmology department were included as "control". Both groups had blood sampling and OCT-A imaging. Retina microvascularization density in the superficial capillary plexus was measured on 3 × 3 mm angiograms centered on the macula. Angiopoietin-2, TGF-β1, osteoprotegerin, GDF-15 and ST-2 were explored with ELISA or multiplex method. Overall, 62 eyes of ACS patients and 42 eyes of controls were included. ACS patients had significantly lower inner vessel length density than control patients (p = 0.004). A ROC curve found that an inner vessel length density threshold below 20.05 mm^-1 was moderately associated with ACS. Significant correlation was found between serum levels of angiopoietin-2 and osteoprotegerin, and retinal microvascularization in OCT-A (R = - 0.293, p = 0.003; R = - 0.310, p = 0.001). Lower inner vessel length density measured with OCT-A was associated with ACS event and was also correlated with higher concentrations of angiopoietin-2 and osteoprotegerin.

Effect of systemic blood pressure on optical coherence tomography angiography in glaucoma patients

BACKGROUND

The association between retinal microvascular structure and glaucoma has been revealed in multiple studies using optical tomography angiography (OCTA), but limited information on the macular vessel density (mVD) in patients with glaucoma is available. In this study, we tried to identity the factors that affected macular VD (mVD) in glaucomatous eyes.

METHODS

This retrospective cross-sectional study evaluated OCT and OCTA images from 92 eyes from 58 healthy subjects and 179 eyes from 103 glaucoma patients using the SD-OCT database from July 2017 to July 2018. Glaucomatous eyes were further divided into two groups according to history of disc haemorrhage (DH). Association between mVD and demographic characteristics, ganglion cell-inner plexiform layer (GCIPL) thickness, visual field mean deviation (MD) and systemic blood pressure was analysed in each group.

RESULTS

In both healthy and glaucomatous eyes, mVD was inversely associated with age (β = -0.035, P = 0.025; β = -0.039, P = 0.018). In the glaucomatous eyes, mVD was significantly decreased, as the MD value was worse (β = 0.109, P = 0.002). In glaucomatous eyes with DH, mVD decreased as blood pressure increased (β = -0.111, P = 0.003) CONCLUSIONS: Reduced mVD is more common in older individuals in both healthy and glaucomatous eyes, and correlates with functional deterioration than structural damage in glaucomatous eyes. In glaucomatous eyes with DH, high systemic BP is associated with a reduction in mVD. This may indicate that glaucoma patients with DH are more susceptible to vascular damage secondary to hypertension.

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.

Automatic Segmentation of Retinal Capillaries in Adaptive Optics Scanning Laser Ophthalmoscope Perfusion Images Using a Convolutional Neural Network

Purpose

Adaptive optics scanning laser ophthalmoscope (AOSLO) capillary perfusion images can possess large variations in contrast, intensity, and background signal, thereby limiting the use of global or adaptive thresholding techniques for automatic segmentation. We sought to develop an automated approach to segment perfused capillaries in AOSLO images.

Methods

12,979 image patches were extracted from manually segmented AOSLO montages from 14 eyes and used to train a convolutional neural network (CNN) that classified pixels as capillaries, large vessels, background, or image canvas. 1764 patches were extracted from AOSLO montages of four separate subjects, and were segmented manually by two raters (ground truth) and automatically by the CNN, an Otsu's approach, and a Frangi approach. A modified Dice coefficient was created to account for slight spatial differences between the same manually and CNN-segmented capillaries.

Results

CNN capillary segmentation had an accuracy (0.94), a Dice coefficient (0.67), and a modified Dice coefficient (0.90) that were significantly higher than other automated approaches (P < 0.05). There were no significant differences in capillary density and mean segment length between manual ground-truth and CNN segmentations (P > 0.05).

Conclusions

Close agreement between the CNN and manual segmentations enables robust and objective quantification of perfused capillary metrics. The developed CNN is time and computationally efficient, and distinguishes capillaries from areas containing diffuse background signal and larger underlying vessels.

Translational Relevance

This automatic segmentation algorithm greatly increases the efficiency of quantifying AOSLO capillary perfusion images.

Comparison of Peripapillary Capillary Density in Glaucoma Patients of African and European Descent

PURPOSE

To evaluate racial differences in optic nerve head peripapillary capillary density measured by OCT angiography (OCTA) in patients with open-angle glaucoma.

DESIGN

Observational, cross-sectional study.

PARTICIPANTS

Two hundred eighty-four eyes of 195 glaucoma patients and 108 eyes of 58 healthy participants from the Diagnostic Innovations in Glaucoma Study.

METHODS

Global and sectoral circumpapillary capillary density (cpCD) loss in participants of European descent (ED) and African descent (AD) were compared. Areas under the receiver operating characteristic curve (AUROCs) were used to evaluate diagnostic accuracy of cpCD and global circumpapillary retinal nerve fiber layer (cpRNFL) thickness in the 2 groups after adjusting for confounders.

MAIN OUTCOME MEASURES

Peripapillary capillary density and cpRNFL thickness measurements and their estimated loss.

RESULTS

Participants of AD and ED with glaucoma were of similar age and glaucoma severity. After adjusting for age, disc area, and other confounders, significantly lower cpCD was found in ED eyes compared with AD eyes in mild glaucoma (mean, 42.2% [95% confidence interval (CI), 41.2%-43.2%] and 46.5% [95% CI, 44.8%-48.1%], respectively; adjusted difference, 4.4 [95% CI, 2.6-6.2]; P < 0.001) and moderate to advanced glaucoma (mean, 34.7% and 38.5%, respectively; adjusted difference, 4.8 [95% CI, 1.6-8.1]; P = 0.005). Although capillary density loss was greater in all sectors in ED compared with AD participants, a similar sectoral pattern of density loss was observed in both racial groups. Lower mean deviation and older age were associated with lower cpCD in both races in multivariate models. The adjusted AUROC for discriminating between healthy and glaucomatous eyes for cpCD was higher for ED (0.95) compared with AD (0.68) patients (P < 0.001). Sensitivity at 95% specificity in AD participants was lower than in ED participants for cpCD (0.32 [95% CI, 0.11-0.64] vs. 0.83 [95% CI, 0.69-0.93], respectively; P < 0.001).

CONCLUSIONS

Although peripapillary capillary density parameters showed good diagnostic accuracy for detecting glaucoma in ED patients, their diagnostic accuracy was only modest in AD patients. Diagnostic performance of cpCD is race dependent, and clinicians should be aware that it has poorer performance in AD patients.

Effect of Scan Size on Glaucoma Diagnostic Performance Using OCT Angiography En Face Images of the Radial Peripapillary Capillaries

PRECIS

When comparing 4.5×4.5 mm to 6.0×6.0 mm optical coherence tomography angiography scans of the radial peripapillary capillaries (RPCs) for glaucoma diagnostic capability, there was a trend of 4.5 scans outperforming 6.0 scans, especially for inferior, nasal, and superior quadrants.

OBJECTIVES

The main purpose of this study was to compare diagnostic ability of peripapillary vessel parameters from 4.5×4.5 mm (4.5) and 6.0×6.0 mm (6.0) spectral-domain optical coherence tomography angiography scans of the RPC in detecting primary open-angle glaucoma from nonglaucoma eyes.

METHODS

Consecutive patients from an academic glaucoma clinic underwent 4.5 and 6.0 scans (CIRRUS HD-OCT 5000 with AngioPlex OCT Angiography; ZEISS, Dublin, CA). Automatic segmentation created en face RPC images. Vessel area density, vessel skeleton density, and flux were calculated using custom quantification software, and perfusion density and flux index (FI) using automated quantification software. Area under the curve statistics included age and hypertension in the analysis.

RESULTS

Of 173 eyes from 123 patients who underwent both 4.5 and 6.0 imaging, 32 primary open-angle glaucoma eyes from 32 patients and 95 nonglaucoma eyes from 95 patients were studied. For the global region of 4.5 versus 6.0 scans, area under the curve was 0.940 and 0.916 for vessel area density (P=0.286); 0.941 and 0.921 for vessel skeleton density (P=0.385); 0.942 and 0.916 for flux (P=0.239); 0.912 and 0.884 for perfusion density (P=0.103); and 0.913 and 0.865 for FI (P=0.159), respectively. For the quadrant regions, 4.5 images significantly outperformed 6.0 images for the superior and inferior quadrants for flux and superior and nasal quadrants for FI (P-values=0.007, 0.047, 0.011, 0.007, respectively); other quadrant differences were not significant.

CONCLUSIONS

Parameters from 4.5 scans generally outperformed those from 6.0 scans in the global and quadrant regions, suggesting greater digital resolution in 4.5 scans of the immediate peripapillary RPC is important in detecting glaucomatous changes.

A comprehensive map of disease networks and molecular drug discoveries for glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. The molecular etiology of glaucoma is complex and unclear. At present, there are few drugs available for glaucoma treatment. The aim of the present study was to perform a systematic analysis of glaucoma candidate drugs/chemicals based on glaucoma genes, including genetic factors and differentially expressed (DE) genes. In total, 401 genes from the genetic databases and 1656 genes from the DE gene analysis were included in further analyses. In terms of glaucoma-related genetic factors, 54 pathways were significantly enriched (FDR < 0.05), and 96 pathways for DE genes were significantly enriched (FDR < 0.05). A search of the PheWAS database for diseases associated with glaucoma-related genes returned 1,289 diseases, and a search for diseases associated with DE glaucoma-related genes returned 1,356 diseases. Cardiovascular diseases, neurodegenerative diseases, cancer, and ophthalmic diseases were highly related to glaucoma genes. A search of the DGIdb, KEGG, and CLUE databases revealed a set of drugs/chemicals targeting glaucoma genes. A subsequent analysis of the electronic medical records (EMRs) of 136,128 patients treated in Sichuan Provincial People’s Hospital for candidate drug usage and the onset of glaucoma revealed nine candidate drugs. Among these drugs, individuals treated with nicardipine had the lowest incidence of glaucoma. Taken together with the information from the drug databases, the 40 most likely candidate drugs for glaucoma treatment were highlighted. Based on these findings, we concluded that the molecular mechanism of glaucoma is complex and may be a reflection of systemic diseases. A set of ready-to-use candidate drugs targeting glaucoma genes may be developed for glaucoma clinical drug treatments. Our results provide a systematic interpretation of glaucoma genes, interactions with other systemic diseases, and candidate drugs/chemicals.

Analysis of Foveal and Parafoveal Microvascular Density and Retinal Vessel Caliber Alteration in Inactive Graves' Ophthalmopathy

Purpose

We aimed to evaluate foveal and parafoveal density using optical coherence tomography angiography and the alteration on the retinal vessel diameter in patients with inactive Graves' ophthalmopathy compared to age-matched normal population. Materials and Methods. Patients with inactive Graves' ophthalmopathy (study group) and healthy individuals (control group) were enrolled in the cross sectionally designed study. The optical coherence tomography angiography parameters and retinal vessel diameter measurements were assessed between the study and control groups. Foveal and parafoveal microvascular density in the retina was measured using optical coherence tomography angiography. Retinal artery and vein diameter and artery/vein ratio were assessed for retinal vessel caliber changes.

Results

Patients with inactive Graves' ophthalmopathy had higher values of intraocular pressure, proptosis, and axial length (P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001,

Conclusion

Optical coherence tomography angiography could be a novel and promising noninvasive diagnostic technique in patients with inactive Graves' ophthalmopathy to detect foveal and parafoveal vessel density changes compared to healthy subjects. The decrease of retinal vessel diameter might be observed in patients with inactive graves ophthalmopathy.

Association Between Parapapillary Choroidal Vessel Density Measured With Optical Coherence Tomography Angiography and Future Visual Field Progression in Patients With Glaucoma

Importance

Investigating the vascular risk factors of glaucoma progression is important to individualize treatment; however, few studies have investigated these factors because the available methods have proven insufficient to evaluate the vascular features of patients with glaucoma. Recently, the advent of optical coherence tomography angiography (OCT-A) allowed both qualitative and quantitative microvascular data to be obtained, to in turn evaluate the perfusion status of different retinal layers.

Objective

To determine whether baseline parapapillary choroidal vessel density (VD) as measured by OCT-A was associated with future glaucoma progression.

Design, Setting, and Participants

A prospective, observational, comparative study was conducted at Seoul St Mary's Hospital of The Catholic University of Korea from March 1, 2016, to December 31, 2018, for 108 glaucomatous eyes in which the retinal nerve fiber layer thickness and mean deviation were measured by at least 5 serial OCT and visual field (VF) examinations. The participants underwent OCT-A at baseline. Vessel density was measured using the en face image of the choroidal map of OCT-A within the β-zone parapapillary atrophy region.

Main Outcomes and Measures

Parapapillary choroidal VD, retinal nerve fiber layer thinning rate, mean deviation rate, and progression of glaucoma as measured by OCT and VF.

Results

Among 108 patients (74 women and 34 men; mean [SD] age, 59.2 [13.1] years), 38 (35.2%) showed progression of glaucoma as measured by OCT and 34 (31.5%) showed progression of glaucoma as measured by VF at the last follow-up. The mean (SD) follow-up duration was 2.6 [2.3] years. The presence of disc hemorrhage (odds ratio, 5.57; 95% CI, 3.18-8.29; P = .001), baseline mean deviation (odds ratio, 0.83; 95% CI, 0.71-0.97; P = .02), and parapapillary choroidal VD (odds ratio, 1.18; 95% CI, 1.09-1.28; P = .01) were associated with progression of glaucoma as measured by VF, but not with progression of glaucoma as measured by OCT. Baseline parapapillary choroidal VD (β, 1.08; 95% CI, 1.02-1.13; P < .001) was associated with progression of glaucoma as measured by VF using Cox proportional hazards regression analysis.

Conclusions and Relevance

These data suggest that lower parapapillary choroidal VD within the β-zone parapapillary atrophy at baseline among individuals with glaucoma could play some role in the risk of progression of glaucoma as measured by VF. The findings suggest that patients with glaucoma with lower parapapillary choroidal VD within the β-zone parapapillary atrophy at baseline warrant careful monitoring for progression of glaucoma as measured by VF.

Optical coherence tomography angiography for the measurement of optic disc: Macular relationship

INTRODUCTION

Fundus photography is the gold standard for assessing ocular torsion over the last 30 years. However, it is not a precise and reproducible tool during clinical practice. Optical coherence tomography angiography is characterized by precise identification of the macula and the optic disc, and it could be an effective method to easily calculate the angle of ocular torsion, compared to fundus photography. The aim of this study was to show whether any difference in the measurement and the accuracy of the angle of torsion between the head of the optic nerve and the fovea was present.

METHODS

This is a prospective single-, referral-center study conducted at the San Giuseppe Hospital in Milan on 80 eyes of 40 adult patients, included in a random-sample way. Exclusion criteria were non-cooperation, higher refractive errors of ±3 diopters, retinal and optic disc pathologies, and ocular movement disorders.

RESULTS

Patients' mean age was 54.3 ± 16.3 (range: 22-83) years. The angle measured by the fundus camera was 7.78° ± 3.04°, while the angle measured by the angiography was 7.09° ± 3.08° (p = .035). The mean interocular difference was 1.54° ± 3.42° for fundus photography and 0.5° ± 4.71° for angiography (p = .013).

CONCLUSION

Optical coherence tomography angiography is a very useful, fast, precise, reproducible, and reliable technique in cooperative subjects, not inferior to the fundus camera and less prone to human error.

Macular Vessel Density Measured With Optical Coherence Tomography Angiography and Its Associations in a Large Population-Based Study

Purpose

We investigate macular perfusion and the systemic and ocular associations in a population-based setting.

Methods

In this cross-sectional study, 2018 adults residing in Hong Kong underwent detailed ophthalmic examinations after consenting to participate. Macular perfusion was measured with optical coherence tomography angiography (OCTA) using the split-spectrum amplitude decorrelation angiography algorithm. The parafoveal flow index and vessel area density were quantified using automated custom-built software.

Results

Of the 2018 participants, the OCTA measurements were available for 1940, and 1631 (84.1%) had good quality scans. The right eyes of these 1631 participants (43.1% men) were included for final analysis. Mean age was 49.8 years (range, 18-92 years). Mean global macular vessel density was 47.3% and 55.1% for the superficial and deep retinal layers, respectively. In multivariate analysis, lower superficial vessel density remained significantly associated with lower signal strength index (SSI; P < 0.001, standardized β = 0.607) and male sex (P < 0.001, β = 0.162), and borderline associated with older age (P = 0.09, β = -0.045) and longer axial length (AL; P = 0.09, β = -0.037), while lower deep layer vessel density was significantly associated with lower SSI (P < 0.001, standardized β = 0.667), longer AL (P < 0.001, β = -0.097), and higher creatinine (P < 0.001, β = -0.072).

Conclusions

This large population-based study provided normative OCTA data of macular vessel density and demonstrated that a lower superficial retinal vessel density was significantly associated with lower SSI and male sex, while a lower deep layer retinal vessel density was significantly associated with lower SSI, longer AL, and higher level of creatinine. These associations must be considered when interpreting clinical quantitative OCTA data.

Ganglion Cell Complex Thickness and Macular Vessel Density Loss in Primary Open-Angle Glaucoma

PURPOSE

To characterize the change rate of ganglion cell complex (GCC) thickness and macular vessel density in healthy, preperimetric glaucoma and primary open-angle glaucoma (POAG) eyes.

DESIGN

Prospective, longitudinal study.

PARTICIPANTS

One hundred thirty-nine eyes (23 healthy eyes, 36 preperimetric glaucoma eyes, and 80 POAG eyes) of 94 patients who had at least 3 visits were included from the Diagnostic Innovations in Glaucoma Study. The mean follow-up was 2.0 years for healthy eyes, 2.6 years for preperimetric glaucoma eyes, and 2.6 years for POAG eyes.

METHODS

OCT angiography (OCTA)-based vessel density and OCT-based structural thickness of the same 3×3-mm² GCC scan slab were evaluated. The dynamic range-based normalized rates of vessel density and thickness change were calculated and compared within each diagnostic group. The association between the rates of thickness and vessel density change and potential factors were evaluated.

MAIN OUTCOME MEASURES

The rates of GCC thinning and macular vessel density loss.

RESULTS

Significant rates of GCC thinning and macular vessel density decrease were detectable in all diagnostic groups (all P < 0.05). In healthy eyes and preperimetric glaucoma eyes, the normalized rates of GCC thinning and macular vessel density decrease were comparable (all P > 0.1). In contrast, the normalized rate (mean, 95% confidence interval) of macular vessel density decrease in the POAG eyes (-7.12 [-8.36, -5.88]%/year) was significantly faster than GCC thinning (-2.13 [-3.35, -0.90]%/year; P < 0.001). In the POAG group, more than two thirds of the eyes showed faster macular vessel density decrease than GCC thinning; faster macular vessel density decrease rate was associated significantly with worse glaucoma severity (P = 0.037). The association between GCC thinning rate and glaucoma severity was not significant (P = 0.586). Intraocular pressure during follow-up significantly affected the rate of GCC thinning in all groups (all P < 0.05) but showed no association with the rate of macular vessel density decrease.

CONCLUSIONS

Both GCC thinning and macular vessel density decrease were detectable over time in all diagnostic groups. In POAG eyes, macular vessel density decrease was faster than GCC thinning and was associated with severity of disease. Macular vessel density is useful for evaluating glaucoma progression, particularly in more advanced disease.

Vessel Density in Glaucoma of Different Entities as Measured with Optical Coherence Tomography Angiography

Purpose

To compare papillary and macular vessel density (VD), as measured by optical coherence tomography angiography (OCTA), in eyes with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and exfoliation glaucoma (XFG).

Methods

The papillary and macular VD of 40 eyes with POAG, 19 with NTG and 21 with XFG were examined using OCTA (AngioVue™). The VD was measured at two different layers of segmentation (optic nerve head: radial peripapillary capillary [RPC] and nerve head [NH]; macula: superficial [SL] and deep [DL] retinal vascular plexus) with a 4.5×4.5mm papillary and 6×6-mm macular scan. VD was calculated by an automated density measuring tool in the AngioVue™ software.

Results

There were no significant differences in the total value of the papillary, peripapillary and macular VD. A significantly higher VD could be measured for NTG compared to POAG, as well as for XFG in the inferior nasal peripapillary sector at RPC-segmentation and at the NH-level between NDG and XFG.

Conclusion

OCTA can detect a difference in VD in the nasal inferior peripapillary sector in NTG compared with POAG and XFG. These findings may help to improve the understanding of further pathophysiological mechanisms.

Optical coherence tomography angiography-derived flow density: a review of the influencing factors

Research interest in the possibility of quantifying macular and optic nerve head perfusion through optical coherence tomography angiography (OCTA) is rapidly advancing. Numerous scientific trials have furthered our understanding of the capabilities and the limitations of this novel technology, while applying OCTA to various ocular pathologies. In recent years, different parameters such as age, gender, intraocular pressure, spherical equivalent, physical activity, systemic diseases, and medication have been shown to have a significant impact on quantitative OCTA metrics. Since OCTA is likely to remain a "hot topic" in the near future, it is crucial to be aware of influencing factors in order to ensure correct interpretation of imaging results. This article reviews the factors currently known to influence flow density (FD) as measured by OCTA in healthy eyes.

Comparison of the Repeatability of Macular Vascular Density Measurements Using Four Optical Coherence Tomography Angiography Systems

The aim of this study was to compare the repeatability of optical coherence tomography angiography (OCT-A) measurements of macular vessel density using four OCT-A systems, including Heidelberg Spectralis HRA, Optovue RTVue XR, Zeiss Cirrus HD-OCT 5000, and Topcon DRI OCT Triton. A cross-sectional design was used for this study. The vascular density and vascular length density of the superficial and deep retinal capillary plexuses were imaged with OCT-A using 3 mm and 6 mm scan patterns and were calculated using ImageJ. Comparisons of intraclass correlation coefficients (ICC) were conducted. We found that the OCT-A systems had various levels of repeatability. Zeiss had better repeatability for vessel density than the other systems (overall ICC = 0.936). Optovue had better repeatability for vessel length density when the 6 mm scan pattern was used (ICC = 0.680 and 0.700 for retinal superficial and deep capillary plexus, respectively). We concluded that repeatability varied when different scan patterns of various OCT-A systems were used for imaging the superficial retinal and deep capillary plexuses. Results should be seen as valid only for a given method. The repeatability of various OCT-A systems should be considered in clinical practice and in clinical trials that use OCT-A metrics as outcome measures.

Optical Coherence Tomography Angiography Macular Vascular Density Measurements and the Central 10-2 Visual Field in Glaucoma

PURPOSE

To evaluate the association between macula vascular density assessed by optical coherence tomography angiography (OCT-A) and central visual field (VF) threshold sensitivities in healthy, glaucoma suspect, and glaucoma patients.

METHODS

A total of 185 eyes from 38 healthy participants, 31 glaucoma suspects, 72 mild glaucoma patients, and 44 moderate/severe glaucoma patients from the Diagnostic Innovations in Glaucoma Study who underwent OCT-A images of the macula and 10-2 VF testing were enrolled in this observational cross-sectional study. The relationship between central VF mean sensitivity (MS) and superficial macula whole-image vessel density (wiVD), and the relationship between the MS of the 4 central points of the 10-2 VF (MS4) and parafoveal vessel density (pfVD), were assessed using linear regression models.

RESULTS

Mean wiVD (52.5%, 49.8%, 49.4% and 45.2%, respectively) and mean pfVD (54.9%, 52.1%, 51.8% and 47.7%, respectively) were found to be significantly higher in healthy eyes and glaucoma suspect eyes compared with glaucoma eyes with mild and moderate/severe disease [analysis of covariance (ANCOVA) P<0.001]. The univariate associations between 10-2 MS and wiVD (R=26.9%) and between 10-2 MS4 and pfVD (R=16.8%) were statistically significant (P<0.001 for both). After adjusting for scan quality, age, sex and intraocular pressure, superficial macula wiVD and pfVD were still independently associated with central VF loss. Macula wiVD performed better [area under the receiver operator characteristic (AUROC)=0.70] than ganglion cell complex thickness (AUROC=0.50) for differentiating between glaucoma suspect and healthy eyes (P=0.010).

CONCLUSIONS

Loss of OCT-A macula vessel density is associated with central 10-2 VF defects. Macula vessel density is a clinically relevant parameter that may enhance monitoring of glaucoma suspects and patients.

Differences in macular capillary parameters between healthy black and white subjects with Optical Coherence Tomography Angiography (OCTA)

PURPOSE

To investigate if there are differences in macular capillaries between black and white subjects using optical coherence tomography angiography (OCTA) and identify potential factors underlying the epidemiologically-based higher vulnerability of black populations to diabetic retinopathy (DR).

METHODS

This prospective, observational cross-sectional study included 93 eyes of 47 healthy subjects with no medical history and ocular history who self-identified as black or white and were matched for age, sex, refractive error, and image quality. Subjects underwent OCTA imaging (RTVue-XR Avanti) of the superficial (SCP) and deep (DCP) capillary plexuses and choriocapillaris. AngioAnalytics was used to analyze vessel density (VD) and choriocapillaris % blood flow area (BFA) in the 1mm-diameter fovea, parafovea, and 3mm-diameter circular area including the fovea and parafovea (3x3mm image). Foveal avascular zone (FAZ) was also analyzed. Linear mixed models were used to evaluate for differences between the study groups.

RESULTS

Compared to the white subjects in this study, black subjects were found to have: lower foveal VD in the SCP (p<0.05); lower VD in the parafovea and in the 3x3mm image in the DCP (p<0.05); larger FAZ in SCP and DCP (p<0.05); and decreased choriocapillary BFA in the area underlying the fovea, parafovea, and 3x3mm image (p<0.05).

CONCLUSION

In our study, our black subjects had decreased macular capillary vasculature compared to matched white subjects, even in early adulthood and the absence of any systemic or ocular conditions. To our knowledge, this is the first report showing that retinal and choriocapillary vascular differences may contribute to racial disparities in vulnerability to DR.

Papillary Vessel Density Changes After Intravitreal Anti-VEGF Injections in Hypertensive Patients with Central Retinal Vein Occlusion: An Angio-OCT Study

PURPOSE

To investigate papillary microvascular changes in patients affected by macular edema due to Central Retinal Vein Occlusions (CRVO) after anti-Vascular Endothelial Growth Factor (VEGF) therapy.

METHODS

Prospective analysis of papillary and peripapillary vessel density (VD) changes in 18 eyes of 18 hypertensive patients affected by CRVO before and after the loading-phase of intravitreal Ranibizumab (IVR) injections. Data were quantitatively measured by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) before as well as 1 month and 4 months after injections. The correlation between post-treatment best-corrected visual acuity (BCVA) and changes in the retinal microvasculature evaluated by OCTA was assessed. Results: 18 eyes of 18 consecutive patients with a known history of arterial hypertension and affected by an acute CRVO episode were enrolled. Central macular thickness (CMT) was significantly reduced after IVR injections (p < 0.001), while mean BCVA improved from 0.70 ± 0.26 logarithm of the minimal angle of resolution (logMAR) units at baseline to 0.25 ± 0.18 logMAR units after 4 months (p < 0.001). VD inside disc and peripapillary significantly increased (p < 0.001 and p = 0.01, respectively) after treatment.

CONCLUSIONS

OCTA showed VD increase in the papillary area in patients affected by CRVO after anti-VEGF therapy. This area could represent a new region of interest to study microvasculature changes concomitant with severe macular edema.

Influence of mydriasis on optical coherence tomography angiography imaging in patients with age-related macular degeneration

Purpose

To evaluate the effect of topical mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with age-related macular degeneration (AMD).

Methods

27 eyes of 27 patients suffering from AMD were included in this cross-sectional study. Patients with ≥-4.5 diopters spherical equivalent, corneal opacities or dense cataract preventing high-quality imaging were excluded. Whole-en-face scans of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the central 3x3mm foveal region as well as whole-en-face and peripapillary scans of the radial peripapillary capillaries (RPC) were generated using OCTA (AngioVue®, Optovue). Imaging was first conducted with patients’ eyes in miosis, then in mydriasis after instillation of a dilating eye drop (0.5% tropicamide, 2.5% phenylephrine-HCl). Main outcome measures were flow density (FD), foveal avascular zone (FAZ), signal strength index (SSI) and motion artifact score (MAS).

Results

Our results reveal that in AMD patients there is no significant difference between FD measurements taken in miosis and those taken in mydriasis around the SCP (p = 0.198), DCP (p = 0.458), RPC whole-en-face (p = 0.275) and RPC peripapillary (p = 0.503). Measurements taken in these two states appear to be equivalent for assessment of FD (90%CI within ± 0.05). No significant difference was found either in the area of the FAZ (p = 0.338) or in the SSI (p = 0.371) before and after the instillation of tropicamide/phenylephrine. MAS was significantly lower after the application of mydriatic eye drops (p = 0.003).

Conclusions

Our findings reveal that neither measurements of FD nor measurements of the FAZ area changed significantly in AMD patients after the application of tropicamide/phenylephrine. Since MAS improved significantly in dilation, mydriatic examination is recommended. Nevertheless, a comparison of OCTA metrics from images taken with different pupil states (miosis versus mydriasis) is valid for clinical trials.

Diurnal Stability Of Peripapillary Vessel Density And Nerve Fiber Layer Thickness On Optical Coherence Tomography Angiography In Healthy, Ocular Hypertension And Glaucoma Eyes

Purpose

By using optical coherence tomography angiography (OCTA), to evaluate diurnal changes of the following parameters: vessel density in the peripapillary area (PP-VD) and in the optic nerve head (ONH-VD); thickness of retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC).

Methods

All prospectively enrolled participants were imaged on the same day at 8 am and 7 pm by means of the XR Avanti device with AngioVue and AngioAnalytics software (Optovue Inc., Fremont, CA, USA). Only eyes with correct automatic segmentation and good-quality images (scan quality > 7/10) were included.

Results

Forty-six eyes from 28 patients with glaucoma, 53 from 31 patients with ocular hypertension, and 62 from 38 controls were assessed. The mean measurements of all parameters investigated were significantly different in the morning and in the evening values in all three groups, with lower values in glaucomatous eyes (p<0.014). In control eyes, as well as in eyes of patients with ocular hypertension and glaucoma the daily changes were minimal and not statistically significant with means of +0.17%, −0.31% and −0.54% for ONH-VD (p=0.83) and means of +0.2%, +0.1% and +0.29% for PP-VD (p=0.83), respectively. Likewise, daily fluctuations in GCC and RNFL thickness were not significant in any of the three groups, with means of +0.16 µm, +0.66 µm and −0.15 µm for GCC (p=0.58) and means of +0.24 µm, +0.58 µm and −0.24 µm for ONH-RNFL (p=0.90), respectively. Systemic hypertension, age, axial length, daily changes in intraocular pressure or scan quality did not correlate with daily fluctuations of any of the parameters investigated (p>0.1).

Conclusion

Vessel density, GCC and RNFL were stable during daytime thus corroborating the clinical relevance of OCTA regardless the time of acquisition.

Association of Macular and Circumpapillary Microvasculature with Visual Field Sensitivity in Advanced Glaucoma

PURPOSE

To evaluate the association between optical coherence tomography angiography (OCTA) macular and circumpapillary vessel density and visual field mean deviation (MD) in advanced primary open angle glaucoma.

DESIGN

Cross-sectional study.

METHODS

Macula (superficial layer) and optic nerve head (ONH) with capillary density (CD) and without vessel density (VD) automated removal of large vessels OCTA of 34 eyes (34 patients, MD < -10 dB) were investigated as macula whole image VD (wiVD), parafoveal VD (pfVD), ONH wiVD, wiCD, circumpapillary VD, and cpCD. Spectral domain OCT circumpapillary retinal nerve fiber layer, macular ganglion cell complex, and ganglion cell inner plexiform layer were also analyzed.

RESULTS

Macular and ONH VD decreased significantly with worsening MD. Each 1-dB decrease in MD was associated with a reduction of 0.43% and 0.46% for macular wiVD and pfVD with R² of 0.28 and 0.27, respectively (all P < .01). The association between MD and VD was strongest for measures of ONH with large vessels removed, wiCD, and cpCD, followed by wiVD and circumpapillary VD with R² of 0.26, 0.22, 0.17, 0.14, and a VD reduction of 0.43%, 0.51%, 0.33%, and 0.40%, respectively (all P < .02). There was a reduction of 1.19 μm in Avanti parafoveal ganglion cell complex, 1.13 μm in Spectralis ganglion cell inner plexiform layer, and 1.01 μm in Spectralis circumpapillary retinal nerve fiber layer, with R² of 0.19 (P = .006), 0.23 (P = .002), and 0.24 (P = .002), respectively.

CONCLUSIONS

ONH and macula OCTA VD and thickness are associated with the severity of visual field damage in advanced primary open angle glaucoma.

Effect of cold provocation on vessel density in eyes with primary open angle glaucoma: An optical coherence tomography angiography study

The cold pressor test (CPT) induces a cardiovascular response, which may affect ocular blood flow and neuronal function. This study assessed whether optical coherence tomography angiography (OCT-A) can be used to evaluate CPT-induced changes in healthy eyes and in eyes with primary open-angle glaucoma (POAG). Twenty-two healthy subjects and 23 subjects with POAG and retinal fibre layer defects in only one hemifield were included in this study. The CPT was performed by submerging a subject’s hand in cold water (0–4 °C) for 1 minute. The results showed that baseline peripapillary and macular vessel density (VD) measurements were significantly lower in subjects with POAG than in controls (all P < 0.05). Post-CPT VD measurements did not significantly differ from baseline in either healthy or glaucomatous eyes. Additionally, CPT-induced changes in VD did not differ among normal eyes, damaged and undamaged glaucomatous hemifields. Changes in VD were also not significantly influenced by self-reported history of cold extremities. In conclusion, the CPT does not induce significant VD changes, as measured by OCT-A, in the peripapillary or macular areas of either healthy eyes or eyes with POAG. The VD, an all-or-nothing flow measure, may not be sensitive enough for evaluating cold-induced ocular haemodynamic changes.

Automated Measurement of the Foveal Avascular Zone in Swept-Source Optical Coherence Tomography Angiography Images

Purpose

The purpose of this study was to evaluate automated measurement of the foveal avascular zone (FAZ) area using the Kanno-Saitama macro (KSM) software in Image J with swept-source optical coherence tomography angiography (SS-OCTA) images.

Methods

In this cross-sectional study, one photographer scanned the macular area (3 × 3 mm) of healthy volunteers twice on the same day, at the same time. The FAZ area was measured from the en face image of the superficial retinal layer by two masked examiners, using the KSM and the Advanced Retina Imaging (ARI)-network method in Carl Zeiss online analysis. Intra- and interscan reproducibility and FAZ area were compared among the methods.

Results

Forty eyes of 22 healthy volunteers were included in the analysis. The mean ± SD age of the subjects was 34.6 ± 12.4 years. Intra- and interscan intraclass coefficients ranged from 0.997 to 1.000 and 0.989 to 0.995, respectively. The mean FAZ area was 0.264 ± 0.08 mm² by the KSM, 0.245 ± 0.08 mm² by the ARI, and 0.281 ± 0.09 mm² by the manual method. The mean difference between the KSM and manual methods was 0.015 mm², which was significantly smaller than the mean difference between the ARI and manual methods (0.034 mm²; P < 0.001).

Conclusions

Automated determination of the FAZ area is feasible and yields results comparable to those obtained by manual measurement. The FAZ area measured with the KSM program is less user dependent and could potentially contribute to our understanding of the pathophysiology of various retinal diseases, particularly underlying vascular diseases.

Translational Relevance

This study demonstrates a novel automated determination of the FAZ area using the Image J macro program in SS-OCTA images. This program was feasible and yields results comparable to those obtained by manual measurement.

Retinal perfusion 6 months after trabeculectomy as measured by optical coherence tomography angiography

PURPOSE

To investigate potential changes of vessel density (VD) at the optic nerve head (ONH) and the macula 6 months after trabeculectomy (TE).

METHODS

In a prospective monocentric study, 19 eyes with open-angle glaucoma were treated with TE + MMC (mitomycin C). At four different time points multiple morphological papillary parameters were measured by OCT, and the ONH VD in the radial peripapillary capillary layer and the superficial and deep plexuses of the macula was determined by OCTA (optical coherence tomography angiography, RTVue-XR, Optovue). The mean defect was determined by visual field examination (mode 30-2, Humphrey Field Analyzer). The duration of follow-up was 6 months.

RESULTS

Nineteen eyes, one each from 19 patients (11 females; 8 males) with a mean age of 66.0 (58.07, 70.94) years and a mean intraocular pressure (IOP) of 21.0 mmHg (17.07, 23.87), were included in the study. All showed a significant reduction in IOP at each follow-up after TE (p < 0.0001). There was no significant change in the peripapillary retinal nerve fiber layer thickness (p = 0.88), the ganglion cell complex (p = 0.97), the cup-disk ratio (p = 0.63), the rim area (p = 0.78), or the mean visual field defect (p = 0.82). With regard to VD, no significant difference could be determined in either the ONH or the macular area.

CONCLUSIONS

After significant surgical reduction of IOP by TE, there are no significant detectable morphological changes in the ONH or the ganglion cell complex as measured by OCT, nor does the papillary or macular OCTA-determined VD change significantly. Trial registration 2016-409-f-S Avanti-OCT-A. Registered December 1, 2016.

The EYE-MI Pilot Study: A Prospective Acute Coronary Syndrome Cohort Evaluated With Retinal Optical Coherence Tomography Angiography

Purpose

To evaluate the association between retinal microvasculature (vascular density) on optical coherence tomography-angiography (OCT-A) and the cardiovascular profile of patients hospitalized for acute coronary syndrome (ACS).

Methods

EYE-Myocardial Infarction (EYE-MI) study is a prospective cross-sectional study in the Cardiology Intensive Care Unit of Dijon University Hospital. Retinal OCT-A was performed for each patient within 2 days after admission. Superficial retinal capillary plexus (SCP) vascular density was measured. The population was divided into tertiles according to OCT-A data.

Results

Overall, 237 cases were retained for analysis. Patients in the tertile with the lowest retinal vascular density (RVD) were older, and more frequently had systemic hypertension and diabetes. Moreover, American Heart Association (AHA) risk and Global Registry of Acute Coronary Events (GRACE) scores were higher and left ventricular ejection fraction (LVEF) was lower in these patients. In multivariate analysis, the AHA risk score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.04-1.09; P < 0.001) and LVEF (OR, 0.95; 95% CI, 0.93-0.98; P = 0.001) were significantly associated with the lowest tertile of RVD. The association between RVD and a high-risk cardiovascular profile was confirmed by a moderate correlation with the GRACE scores (Spearman r = -0.33, P < 0.001).

Conclusions

SCP density measured on OCT-A was associated with the cardiovascular risk profile and with impaired LVEF in patients with a high-risk cardiovascular status. In the future, quantitative retinal microvascular data could be considered a good surrogate of the cardiovascular risk profile and could improve cardiovascular risk assessments.

Reproducibility of macular and optic nerve head vessel density measurements by swept-source optical coherence tomography angiography

PURPOSE

To assess the reproducibility of swept-source optical coherence tomography angiography (SS-OCTA) for macular and optic nerve head (ONH) vessel density (VD).

METHODS

Cross-sectional study using the Triton OCTA (Topcon, Tokyo, Japan), for VD (%) measurements in 40 eyes of 40 healthy subjects on two 6 × 6 mm scans of the macula and ONH across five subfields (central, superior, inferior, temporal, and nasal) at different segmentation levels: superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retina, and choriocapillaris. Reproducibility values were summarized as intraclass correlation coefficients (ICCs) and coefficients of variations (CV).

RESULTS

ICCs for the macular VD measurements in the central zone were 0.874, 0.770, 0.575, 0.718 at the levels SCP, DCP, outer retina, and choriocapillaris, respectively, while worse ICCs were obtained for the parafoveal subfields (ICC ⩽ 0.589); CVs were 2.8%-6.7%. The reproducibility of the ONH superficial VD was ICC = 0.941 for the papillary region and was ICC = 0.499-0.853 for the peripapillary zone; CVs ranged from 4.8% to 17%. Peripapillary VD showed an ICC = 0.533-0.770 in the DCP layer, and 0.572-0.828 in the choriocapillaris. Lowest VD were obtained for the macular SCP and DCP (23% and 22%, respectively), in the foveal zone, while greatest VD were recorded in the nasal and temporal peripapillary subfields at the level of the choriocapillaris (both 68%).

CONCLUSIONS

The new SS-OCTA software served to quantify macular and ONH VD with a reproducibility that was good in the central zones (foveal and papillary, respectively) and moderate in the peripheral zones (parafoveal and peripapillary).

Measurement Floors and Dynamic Ranges of OCT and OCT Angiography in Glaucoma

PURPOSE

To determine if OCT angiography (OCTA)-derived vessel density measurements can extend the available dynamic range for detecting glaucoma compared with spectral-domain (SD) OCT-derived thickness measurements.

DESIGN

Observational, cross-sectional study.

PARTICIPANTS

A total of 509 eyes from 38 healthy participants, 63 glaucoma suspects, and 193 glaucoma patients enrolled in the Diagnostic Innovations in Glaucoma Study.

METHODS

Relative vessel density and tissue thickness measurement floors of perifoveal vessel density (pfVD), circumpapillary capillary density (cpCD), circumpapillary retinal nerve fiber (cpRNFL) thickness, ganglion cell complex (GCC) thickness, and visual field (VF) mean deviation (MD) were investigated and compared with a previously reported linear change point model (CPM) and locally weighted scatterplot smoothing curves.

MAIN OUTCOME MEASURES

Estimated vessel density and tissue thickness measurement floors and corresponding dynamic ranges.

RESULTS

Visual field MD ranged from -30.1 to 2.8 decibels (dB). No measurement floor was found for pfVD, which continued to decrease constantly until very advanced disease. A true floor (i.e., slope of approximately 0 after observed CPM change point) was detected for cpRNFL thickness only. The post-CPM estimated floors were 49.5±2.6 μm for cpRNFL thickness, 70.7±1.0 μm for GCC thickness, and 31.2±1.1% for cpCD. Perifoveal vessel density reached the post-CPM estimated floor later in the disease (VF MD, -25.8±3.8 dB) than cpCD (VF MD, -19.3±2.4 dB), cpRNFL thickness (VF MD, -17.5±3.3 dB), and GCC thickness (VF MD, -13.9±1.8 dB; P < 0.001). The number of available measurement steps from normal values to the CPM estimated floor was greatest for cpRNFL thickness (8.9), followed by GCC thickness (7.4), cpCD (4.5), and pfVD (3.8).

CONCLUSIONS

In late-stage glaucoma, particularly when VF MD is worse than -14 dB, OCTA-measured pfVD is a promising tool for monitoring progression because it does not have a detectable measurement floor. However, the number of steps within the dynamic range of a parameter also needs to be considered. Although thickness parameters reached the floor earlier than OCTA-measured pfVD, there are more such steps with thickness than OCTA parameters.