Repeatability of Peripapillary Optical Coherence Tomography Angiography Parameters in Older Adults

The repeatability of macular and peripapillary vessel density in participants with different severities of glaucoma

PURPOSE

To investigate the repeatability of optical coherence tomography angiography (OCTA) parameters in participants with different severities of glaucoma.

METHODS

Subjects with open-angle glaucoma were enrolled prospectively and categorised into mild (mean deviation [MD] of 24-2 visual field test ≥ -6 dB), moderate to advanced (-6 > MD ≥ -20 dB) and severe glaucoma groups (MD < -20 dB). OCTA was performed three times within a single visit to obtain superficial and deep macular vessel density (VD) and peripapillary vessel and capillary density. The association between the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) of these OCTA parameters and glaucoma severity (MD, the thickness of the retinal nerve fibre layer and the ganglion cell complex) was analysed, along with factors associated with the CoV of OCTA parameters.

RESULTS

A total of 57 mild, 92 moderate to advanced and 39 severe glaucomatous eyes were included. CoV for superficial (p < 0.001) and deep macular VD (p < 0.001) and peripapillary VD (p = 0.004) increased with glaucoma severity. Greater CoV for superficial and deep macular VD and peripapillary VD was associated with worse MD and scan quality index in multivariable analysis. The association between a higher CoV of superficial and deep macular VD and worse MD was only noticeable in participants with a scan quality index <7. The relationship between the CoV of peripapillary VD and MD was consistent across varying image qualities.

CONCLUSION

The intrasession variability of OCTA parameters was greater in glaucoma participants with advanced disease, especially in those with suboptimal scan quality.

Longitudinal Assessment of Peripapillary Microvasculature Using Optical Coherence Tomography Angiography in Cognitively Normal Adults

Introduction: To evaluate longitudinal peripapillary changes in cognitively normal older adults using optical coherence tomography (OCT) and OCT angiography (OCTA). Methods: Participants older than 50 years with no history of neurodegenerative disease or cognitive impairment were prospectively enrolled. OCT and OCTA images were obtained at the first visit and 2 years later. Results: The study comprised 189 eyes of 111 adults with a mean age (±SD) of 69.3 ± 5.8 years and mean follow-up of 2.1 ± 0.5 years. Woman experienced slower rate of decline than men in capillary perfusion density (0.000% ± 0.005% vs -0.002% ± 0.004%; P = .038) and retinal nerve fiber layer (RNFL) thickness (0.133 ± 1.617 µm vs -0.659 ± 1.431 µm; P = .008). At both timepoints, after controlling for sex, the capillary perfusion density (P < .001), capillary flux index (P < .001), and RNFL thickness (P = .005) were lower in older participants. The mean capillary perfusion density was higher in women than in men at both timepoints (P = .01 and P = .002, respectively), with no significant differences in the capillary flux index and RNFL thickness. Conclusions: In cognitively normal adults, there is a significant reduction in peripapillary capillary perfusion density, the capillary flux index, and RNFL thickness associated with aging beyond 50 years. Women had higher capillary perfusion density values with slower rates of change in capillary perfusion density and RNFL thickness. These values can serve as benchmarks, and variations could be suspicious for a pathologic process.

Intrasession Repeatability of OCT Angiography Parameters in Neurodegenerative Disease

Purpose

To assess the intrasession repeatability of macular OCT angiography (OCTA) parameters in Alzheimer's disease (AD), mild cognitive impairment (MCI), Parkinson's disease (PD), and normal cognition (NC).

Design

Cross sectional study.

Subjects

Patients with a clinical diagnosis of AD, PD, MCI, or NC were imaged. Images with poor quality and of those with diabetes mellitus, glaucoma, or vitreoretinal disease were excluded from analysis.

Methods Intervention or Testing

All participants were imaged using the Zeiss Cirrus HD-5000 with AngioPlex (Carl Zeiss Meditec, Software Version 11.0.0.29946) and repeat OCTA images were obtained for both eyes. Perfusion density (PFD), vessel density (VD), and Foveal avascular zone (FAZ) area were measured from 3 × 3 mm and 6 × 6 mm OCTA images centered on the fovea using an ETDRS grid overlay.

Main Outcome Measures

Intraclass correlation coefficients were used to quantify repeatability of PFD, VD, and FAZ area measurements obtained from imaging.

Results

3 × 3 mm scans of 22 AD, 40 MCI, 21 PD, and 26 NC participants and 6 × 6 mm scans of 29 AD, 44 MCI, 29 PD, and 30 NC participants were analyzed. Repeatability values ranged from 0.64 (0.49-0.82) for 6 × 6 mm PFD in AD participants to 0.87 (0.67-0.92) for 3 × 3 mm PFD in AD participants. No significant differences were observed in repeatability between NC participants and those with neurodegenerative disease.

Conclusions

Overall, similar OCTA repeatability was observed between NC participants and those with neurodegeneration. Regardless of diagnostic group, macular OCTA metrics demonstrated moderate to good repeatability.

Financial Disclosures

The authors have no proprietary or commercial interest in any materials discussed in this article.

Convolutional Neural Network-Based Automated Quality Assessment of OCT and OCT Angiography Image Maps in Individuals With Neurodegenerative Disease

Purpose

To train and test convolutional neural networks (CNNs) to automate quality assessment of optical coherence tomography (OCT) and OCT angiography (OCTA) images in patients with neurodegenerative disease.

Methods

Patients with neurodegenerative disease were enrolled in the Duke Eye Multimodal Imaging in Neurodegenerative Disease Study. Image inputs were ganglion cell-inner plexiform layer (GC-IPL) thickness maps and fovea-centered 6-mm × 6-mm OCTA scans of the superficial capillary plexus (SCP). Two trained graders manually labeled all images for quality (good versus poor). Interrater reliability (IRR) of manual quality assessment was calculated for a subset of each image type. Images were split into train, validation, and test sets in a 70%/15%/15% split. An AlexNet-based CNN was trained using these labels and evaluated with area under the receiver operating characteristic (AUC) and summaries of the confusion matrix.

Results

A total of 1465 GC-IPL thickness maps (1217 good and 248 poor quality) and 2689 OCTA scans of the SCP (1797 good and 892 poor quality) served as model inputs. The IRR of quality assessment agreement by two graders was 97% and 90% for the GC-IPL maps and OCTA scans, respectively. The AlexNet-based CNNs trained to assess quality of the GC-IPL images and OCTA scans achieved AUCs of 0.990 and 0.832, respectively.

Conclusions

CNNs can be trained to accurately differentiate good- from poor-quality GC-IPL thickness maps and OCTA scans of the macular SCP.

Translational Relevance

Since good-quality retinal images are critical for the accurate assessment of microvasculature and structure, incorporating an automated image quality sorter may obviate the need for manual image review.

Symmetry of Peripapillary-Optical Coherence Tomography Angiography Parameters between Dominant and Non-dominant Eyes in Normal Eyes

Purpose: To assess whether optical coherence tomography (OCT) measurements and peripapillary microvascular parameters measured via optical coherence tomography angiography (OCTA) were similar between the dominant and non-dominant eyes of normal subjects.Methods: We retrospectively analyzed spectral domain OCT and OCTA data on healthy Koreans. The “hole-in-the-card” technique was used to determine ocular dominance. The perfusion density (PD) and flux index (FI) of the peripapillary 4.5 × 4.5-mm area were measured via OCTA. Central macular, peripapillary retinal nerve fiber layer, and macular ganglion cell-inner plexiform layer thicknesses were measured with the aid of spectral-domain OCT. The OCT and OCTA data of dominant and non-dominant eyes were compared.Results: A total of 84 eyes of 42 healthy subjects were analyzed. The average age was 27.3 ± 5.63 years. Twenty-eight subjects (66.7%) were right eye-dominant and 14 (33.3%) left eye-dominant. None of the central macular (260.00 ± 14.16 μm, 258.71 ± 15.18 μm, <i>p</i> = 0.183), macular ganglion cell-inner plexiform layer (82.02 ± 5.07 μm, 82.43 ± 5.60 μm, <i>p</i> = 0.460), or peripapillary retinal nerve fiber layer thickness (99.36 ± 9.27 μm, 97.90 ± 9.46 μm, <i>p</i> = 0.091) differed between the eyes; neither did any OCTA-assessed microvascular parameter.Conclusions: No OCT or OCTA parameter differed between dominant and non-dominant eyes. No parameter identified ocular dominance.

Identifying Peripapillary Radial Capillary Plexus Alterations in Parkinson's Disease Using OCT Angiography

PURPOSE

To compare radial peripapillary capillary (RPC) plexus vascular parameters and retinal nerve fiber layer (RNFL) thickness between those with Parkinson's disease (PD) and controls.

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

A total of 151 eyes of 81 PD participants and 514 eyes of 266 controls.

METHODS

Participants underwent OCT angiography (OCTA) imaging using the Zeiss Cirrus HD-5000 AngioPlex (Carl Zeiss AG). Capillary perfusion density (CPD) and capillary flux index (CFI) were assessed using a 4.5 × 4.5-mm peripapillary scan, and RNFL thickness was assessed using a 200 × 200-μm optic nerve cube OCT scan. Hoehn and Yahr clinical staging for PD was determined by an experienced movement disorders specialist. Generalized estimating equations adjusted for age and sex were used for analysis.

MAIN OUTCOME MEASURES

Differences in RNFL thickness, CPD, and CFI as assessed using multivariable generalized estimating equations between individuals with PD and controls.

RESULTS

After adjustment for age and sex, average CPD (0.446% ± 0.018% vs. 0.439% ± 0.017%, P < 0.001) and CFI (0.434 ± 0.031 vs. 0.426 ± 0.036, P = 0.008) were significantly higher in PD eyes. Average RNFL thickness was similar between groups (PD 89.71 ± 10.45 μm vs. control 88.20 ± 10.33 μm, P = 0.19). Significant correlations between Hoehn and Yahr stage and OCTA parameters were not observed. The OCTA parameters were not significantly different between eyes of the same patient.

CONCLUSIONS

Increased peripapillary microvascular density and flux were detected in a large cohort of individuals with PD compared with controls after adjusting for age and sex; however, RNFL thickness was similar between groups. Peripapillary OCTA parameters may not correlate with the severity of PD. OCTA may serve as a noninvasive method to identify novel biomarkers for the early diagnosis of PD; as such, this methodology deserves further investigation.