Topographic Correlation Between Juxtapapillary Choroidal Thickness and Microstructure of Parapapillary Atrophy

Characteristics of beta parapapillary atrophy in primary angle-closure suspect

OBJECTIVE

To investigate the characteristics of beta parapapillary atrophy (β-PPA) in patients with primary angle-closure suspect (PACS).

METHODS AND ANALYSIS

In total, 215 and 259 eyes with PACS and non-PACS (NPACS), respectively, were enrolled in this observational, cross-sectional study. Stereoscopic fundus and optical coherence tomography images were used to characterise β-PPA; the former was also used to measure the major β-PPA parameters. Univariate and multiple logistic regression analyses were used to identify the factors correlated with the presence of β-PPA and with β-PPA parameters.

RESULTS

The β-PPA occurrence rates were 48.80% and 44.40% in the PACS and NPACS groups, respectively, with no significant difference between groups. Compared with that in the NPACS group, the β-PPA area was significantly larger (p=0.005) in the PACS group, but the angular extent and maximum radial length did not differ between groups (p=0.110 and 0.657, respectively) after adjusting for age and axial length. The presence of β-PPA was associated with older age (OR 1.057, 95% CI 1.028 to 1.088, p<0.001) and larger disc area (OR 1.716, 95% CI 1.170 to 2.517, p=0.006). A larger β-PPA area was associated with older age (p=0.014), greater vertical cup-to-disc ratio (p=0.028), larger disc area (p<0.001) and PACS diagnosis (p=0.035).

CONCLUSION

48.80% of participants with PACS had β-PPA, which is slightly larger than NPACS. The area of β-PPA was larger in PACS, while the angular extent and maximum radial length did not differ between groups.

Factors Associated with Visual Acuity in Advanced Glaucoma

This study aimed to comprehensively analyze various parameters in advanced glaucoma patients to identify the factors that can affect best-corrected visual acuity (BCVA) in advanced glaucoma. This cross-sectional retrospective study included 113 patients (mean age, 61.66 ± 13.26 years; males, 67) who had advanced glaucomatous damage (113 eyes; mean BCVA, 0.18 ± 0.38 logMAR; mean deviation of 30-2 visual field [VF], -19.08 ± 6.23 dB). Peripapillary retinal nerve fiber layer (RNFL) and total and segmented macular thickness (RNFL, ganglion cell layer (GCL), and inner plexiform layer (GCL)) were measured using Spectralis optical coherence tomography (OCT). Correlations between BCVA and OCT parameters or 30-2 VF parameters were assessed using Pearson correlation analysis. Multivariate regression analysis was performed to determine the factors associated with BCVA in advanced glaucoma patients. Peripapillary RNFL thickness, subfoveal choroidal thickness, and global macular RNFL, GCL, IPL, and total thickness were found to be significantly correlated with BCVA and central visual function. Multivariate analysis showed a significant correlation between subfoveal choroidal thickness and BCVA. In addition, central VF mean sensitivity, especially inferior hemifield, showed a significant relationship with BCVA. In conclusion, subfoveal choroidal thickness and central VF sensitivity, especially the inferior hemifield area, are factors that affect BCVA in advanced glaucoma.

Choroidal Microvasculature Dropout in the Absence of Parapapillary Atrophy in POAG

Purpose

To describe the parapapillary choroidal microvasculature dropout (CMvD) in glaucomatous eyes without β-zone parapapillary atrophy (β-PPA) and compare its characteristics with that of CMvD with β-PPA.

Methods

Peripapillary choroidal microvasculature was evaluated on en face images obtained using optical coherence tomography angiography. CMvD was defined as a focal sectoral capillary dropout with no visible microvascular network identified in the choroidal layer. Peripapillary and optic nerve head structures, including the presence of β-PPA, peripapillary choroidal thickness and lamina cribrosa curvature index were evaluated using the images obtained by enhanced depth-imaging optical coherence tomography.

Results

The study included 100 glaucomatous eyes with CMvD (25 without and 75 with β-PPA) and 97 eyes without CMvD (57 without and 40 with β-PPA). Regardless of the presence of β-PPA, eyes with CMvD tended to have a worse visual field at a given RNFL thickness than eyes without CMvD, with patients having eyes with CMvD having lower diastolic blood pressure and more frequent cold extremities than patients with eyes lacking CMvD. Peripapillary choroidal thickness was significantly smaller in eyes with than without CMvD, but was not affected by the presence of β-PPA. β-PPA without CMvD was not associated with vascular variables.

Conclusions

CMvD were found in the absence of β-PPA in glaucomatous eyes. CMvDs had similar characteristics in the presence and absence of β-PPA. Clinical and optic nerve head structural characteristics potentially relevant to compromised optic nerve head perfusion were dependent on the presence of CMvD, rather than the presence of β-PPA.

Predictive Modeling of Long-Term Glaucoma Progression Based on Initial Ophthalmic Data and Optic Nerve Head Characteristics

Purpose

The purpose of this study was to develop a model, based on initial optic nerve head (ONH) characteristics, predictive of long-term rapid retinal nerve fiber layer (RNFL) thinning in patients with open-angle glaucoma (OAG).

Methods

This study evaluated 712 eyes with OAG that had been followed up for >5 years with annual evaluation of RNFL thickness. Baseline ophthalmic features were incorporated into the machine learning models for prediction of faster RNFL thinning. The model was trained and tested using a random forest (RF) method, and was interpreted using Shapley additive explanations. Factors associated with faster rate of RNFL thinning were statistically evaluated using a decision tree.

Results

The RF model showed that greater lamina cribrosa (LC) curvature, higher intraocular pressure (IOP), visual field mean deviation converging towards −5 dB, and thinner peripapillary choroid at baseline were the four most significant features predicting faster RNFL thinning. Partial interaction between the features showed that larger LC curvature was a strong factor for faster RNFL thinning when it exceeded approximately 12.0. When the LC curvature was ≤12, higher initial IOP and thinner peripapillary choroid played a role in the rapid RNFL thinning. Based on the decision tree, higher IOP (>26.5 mm Hg), greater laminar curvature (>13.95), and thinner peripapillary choroid (≤117.5 µm) were the 3 most important determinants affecting the rate of RNFL thinning.

Conclusions

Baseline ophthalmic data and ONH characteristics of patients with OAG were predictive of eyes at risk of faster progression. Combinations of important characteristics, such as IOP, LC curvature, and choroidal thickness, could stratify eyes into groups with different rates of RNFL thinning.

Translational Relevance

This work lays the foundations for developing prediction models to estimate glaucoma prognosis based on initial ONH characteristics.

Choroidal Thickness and Primary Open-Angle Glaucoma-A Narrative Review

The choroid provides the majority of blood flow to the ocular tissues and structures that facilitate the processes of retinal metabolism responsible for vision. Specifically, the choriocapillaris provides a structural network of small blood vessels that supplies the retinal ganglion cells and deep ocular tissues. Similar to retinal nerve fiber layer thickness, choroidal thickness (CT) has been suggested to represent a quantifiable health biomarker for choroidal tissues. Glaucoma is a disease with vascular contributions in its onset and progression. Despite its importance in maintaining ocular structure and vascular functionality, clinical assessments of choroidal tissues have been historically challenged by the inaccessibility of CT biomarker targets. The development of optical coherence tomography angiography and enhanced depth imaging created a framework for assessing CT and investigating its relationship to glaucomatous optic neuropathy onset and progression. Pilot studies on CT in glaucoma are conflicting-with those both in support of, and against, its clinical utility. Complicating the data are highly customized analysis methods, small sample sizes, heterogeneous patient groups, and a lack of properly designed controlled studies with CT as a primary outcome. Herein, we review the available data on CT and critically discuss its potential relevance and limitations in glaucoma disease management.

Characteristics of Focal Gamma Zone Parapapillary Atrophy

Purpose

The purpose of this study was to investigate the characteristics of focal γ-zone parapapillary atrophy (focal γPPA) in patients with primary open-angle glaucoma (POAG) using spectral-domain optical coherence tomography (SD-OCT).

Methods

Three groups of POAG eyes (n = 214) were defined according to the circumferential extent of Bruch's membrane (BM) within the β-zone PPA, as follows: (1) no γPPA (intact BM; n = 81), (2) conventional γPPA (γPPA involving the fovea-BM-opening axis; n = 89), and (3) focal γPPA (γPPA not involving the fovea-BM-opening axis; n = 44). Clinical and ocular characteristics, including age, axial length (AXL), and focal lamina cribrosa (LC) defects were compared among the three groups.

Results

The focal γPPA group was significantly older (60.6 ± 11.0 years) and had shorter AXL (24.10 ± 1.34 mm) than those of the conventional γPPA group (46.2 ± 13.8 years and 26.53 ± 1.61 mm, respectively; P < 0.001). These values of the focal γPPA group were similar to those of the no γPPA group (23.73 ± 0.97 mm for AXL and 64.0 ± 13.0 years for age). The focal γPPA group had a significantly higher prevalence of focal LC defects than did the other two groups (70.5% [31/44] for the focal γPPA group versus 46.1% [41/89] for the conventional γPPA group versus 37.0% [30/81] for the no γPPA group; P = 0.002).

Conclusions

Focal γPPA was differentiated from conventional γPPA by older age and shorter AXL. Further, focal γPPA was frequently accompanied by focal LC defects. Longitudinal studies elucidating whether focal LC defects and focal γPPA share common pathogenesis are warranted.

Lamina Cribrosa Moves Anteriorly After Trabeculectomy in Myopic Eyes

Purpose

The purpose of this study was to investigate changes in lamina cribrosa (LC) depth after trabeculectomy in myopic eyes using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT).

Methods

Serial horizontal B-scans of the optic nerve head of 41 myopic eyes with primary open-angle glaucoma (POAG) were obtained before and 3 months after trabeculectomy using EDI SD-OCT. LC depth, defined as the distance from the opening plane of Bruch's membrane to the level of the anterior LC surface, was measured before and 3 months after trabeculectomy at 7 locations spaced equidistantly across the vertical optic disc diameter on B-scan images. The mean of the measurements at these seven planes was defined as the average LC depth. Factors associated with changes in LC depth were identified by linear regression.

Results

Intraocular pressure (IOP) decreased from 26.3 ± 9.3 millimeters of mercury (mm Hg) preoperatively to 10.6 ± 3.5 mm Hg 3 months after trabeculectomy. LC depth was significantly lower 3 months after trabeculectomy than preoperatively (P < 0.001, all planes). The magnitude of LC depth reduction was significantly associated with younger age, higher preoperative LC depth, and greater magnitude of IOP reduction (all P ≤ 0.016).

Conclusions

LC depth reduction was observed after trabeculectomy in myopic eyes. The degree of LC depth reduction was not related to the degree of myopia.

Deep-layer Microvasculature Dropout in Preperimetric Glaucoma Patients

PURPOSE

To compare disease severity between preperimetric primary open-angle glaucoma (POAG) patients with and without deep-layer microvasculature dropout.

MATERIALS AND METHODS

Ninety-four eyes of 94 preperimetric POAG patients with β-zone parapapillary atrophy (βPPA) were categorized according to the presence of deep-layer microvasculature dropout defined as a complete loss of microvasculature within the choroid or scleral flange on optical coherence tomography angiography. Parameters representing disease severity, that is, visual field (VF) mean deviation (MD), global and sectoral (6-sector) retinal nerve fiber layer (RNFL) thickness, and other factors including age, focal lamina cribrosa (LC) defect, width of βPPA with and without Bruch membrane (BM) (βPPA+BM and βPPA-BM), and optic disc hemorrhage were compared between eyes with and without dropout.

RESULTS

Deep-layer microvasculature dropout was observed in 33 preperimetric POAG eyes (35.1%). Eyes with dropout had significantly thinner RNFL in all areas except the inferonasal sector, worse VF MD, and higher prevalence of focal LC defect, and larger βPPA-BM (P<0.05), whereas the 2 groups did not differ in age, disc hemorrhage, or βPPA+BM width (P>0.05). In the multivariable logistic regression, worse VF MD [odds ratio (OR), 1.485; P=0.045], thinner RNFL (OR, 1.141; P<0.001), and higher prevalence of focal LC defect (OR, 6.673; P<0.001) were significantly associated with dropout.

CONCLUSIONS

Deep-layer microvasculature dropout was observed in a considerable number of preperimetric POAG eyes, and worse disease severity was associated with dropout. Future studies elucidating the pathogenic role of deep-layer microvasculature dropout in the development and progression of glaucoma are warranted.

Clinical features of microvasculature in subzones of parapapillary atrophy in myopic eyes: an OCT-angiography study

PURPOSE

To investigate the microvasculature in subzones of parapapillary atrophy (PPA) and their associated factors in healthy myopic eyes using optical coherence tomography (OCT) angiography.

METHODS

The cross-sectional study included 55 healthy myopic eyes with PPA. The superficial radial peripapillary capillary (RPC) and choroidal microvascular densities were delineated and measured in alpha, beta, and gamma zone PPA using OCT angiography, respectively. The structural parameters including the width and area in each subzone and corresponding retinal nerve fiber layer thickness were further measured. Statistical analysis was performed to explore the relationship between the vascular and structural parameters.

RESULTS

The mean age and mean axial length of the participants were 27.55 ± 5.72 years and 25.19 ± 1.08 mm. Among alpha, beta, and gamma zone PPA, the beta zone showed the lowest RPC density, which was negatively correlated with the area and width of beta zone (P < 0.05). The gamma zone showed the highest RPC density, which was positively correlated with the retinal nerve fiber layer thickness of gamma zone (P < 0.01). Compared with alpha zone, both gamma and beta zones showed marked decrease of choriocapillaris. The beta zone showed a lower choroidal microvascular density than that of gamma zone (P < 0.01). Choroidal microvascular density in beta and gamma zones were negatively correlated with the width of beta zone and gamma zone, respectively (P < 0.01).

CONCLUSIONS

Topographic differences on superficial RPC and choroidal microvasculature were found among the subzones of PPA. A microcirculatory deficiency in beta zone PPA may exist in myopic eyes.

Microstructure of Nonjuxtapapillary Microvasculature Dropout in Healthy Myopic Eyes

Purpose

The purpose of this study was to characterize the microstructure of the nonjuxtapapillary microvasculature dropout (MvD) in healthy myopic eyes.

Methods

This cross-sectional study included 50 eyes (25 eyes with a nonjuxtapapillary MvD and 25 age-matched eyes without any MvD) from a cohort of 126 nonglaucomatous healthy myopic eyes having parapapillary atrophy (PPA) γ-zone. The parapapillary deep-layer microvasculature was evaluated in en-face images obtained using swept-source optical coherence tomography (OCT) angiography (OCTA). A nonjuxtapapillary MvD was defined as an area with focal absence of vascular signals in the distal portion of PPA confined to the nonjuxtapapillary area. Enhanced depth-imaging OCT scanning was performed to assess the parapapillary microstructure.

Results

Nonjuxtapapillary MvD was found in 25 eyes (19.8%). The parapapillary microstructure at the nonjuxtapapillary MvD in 18 eyes was characterized by the misalignment of Bruch's membrane (BM)–retinal pigment epithelium (RPE) complex, which was identified by the absence of BM-RPE complex and the presence of the inner retina and sclera. In seven eyes with a nonjuxtapapillary MvD but without such misaligned BM-RPE complex, RPE atrophy was observed at the location of the nonjuxtapapillary MvD. Eyes with a nonjuxtapapillary MvD had a longer axial length (AXL; P = 0.013) and a wider γ-zone (P < 0.001) than age-matched control eyes without any MvD.

Conclusions

The microstructure at the nonjuxtapapillary MvD in healthy myopic eyes was characterized in approximately 70% of eyes by temporally misaligned BM-RPE complex. Although the clinical importance of the nonjuxtapapillary MvD remains to be determined, it should be differentiated from the parapapillary choroidal MvD observed in glaucoma.

Correlation between Renal Function and Peripapillary Choroidal Thickness in Treatment-Naïve Diabetic Eyes Using Swept-Source Optical Coherence Tomography

Purpose: To investigate the associations of the estimated glomerular filtration rate (eGFR) with peripapillary choroidal thickness (pCT) and retinal nerve fiber layer (pRNFL) thickness in diabetic patients by using swept-source optical coherence tomography (SS-OCT). Methods: Ocular treatment-naïve patients with type 2 diabetes mellitus registered in the community health system in Guangzhou, China, were recruited to participate in this prospective cross-sectional study. The eGFR was determined using the Xiangya formula, and the renal function was categorized into non-chronic kidney disease (non-CKD), mild CKD, and moderate to severe CKD (MS-CKD) according to the guidelines. The pCT and pRNFL thicknesses at 12 o'clock were obtained using an SS-OCT by a circular scan with a diameter of 3.4 mm centering on the optic nerve head, and the data from only one eye in each patient were used. Results: This study included 1,408 diabetic patients, with a mean age of 64.4 ± 7.8 years. The average pCT decreased with renal function deterioration, with 126.0 ± 58.0 μm for non-CKD, 112.0 ± 51.2 μm for mild CKD and 71.0 ± 22.9 μm for MS-CKD, respectively (P < .001). The pCT was found to be significantly thinner in CKD patients in all quadrantes (P < .05 in all regions) with the exception of the inferior quadrant, and the average pCT was positively correlated with eGFR (β = 0.3, 95%CI = 0.0 to 0.6, P = .021) after adjusting for other factors. The pRNFL thickness in the nasal quadrant was significantly reduced in patients with CKD, and pRNFL thickness was positively correlated with eGFR (β = 0.1, 95%CI = 0.0-0.2, P = .009) after adjusting for other factors. Conclusion: Impaired renal function was associated with a reduction of pCT and pRNFL thickness in patients with type 2 diabetes. The measurement of pCT and pRNFL may provide additional information for predicting renal impairment.

Parapapillary atrophy and changes in the optic nerve head and posterior pole in high myopia

We investigated the relationship between microstructure of β-parapapillary atrophy (β-PPA) and morphologic features of optic nerve head (ONH) and posterior pole in highly myopic eyes. Eighty-nine highly myopic eyes were included in this study. Bruch’s membrane opening (BMO) area, lamina cribrosa (LC) thickness, anterior laminar depth, peripapillary and subfoveal choroidal thickness (CT), macular Bruch’s membrane (BM) length, and width of β-PPA with and without Bruch’s membrane (PPA_+BM and PPA_−BM) were evaluated. The mean age and axial length of the included subjects were 26.88 ± 2.44 years and 27.03 ± 0.88 mm, respectively. The width of PPA_−BM was larger with increasing BMO area (P = 0.001), whereas the BMO area was not associated with the width of PPA_+BM. The large PPA_+BM was significantly related to a thinner LC (P = 0.003), deeper anterior lamina surface (P < 0.001), longer macular BM length (P = 0.008), and thinner temporal peripapillary CT (P = 0.034). We found that the morphologic features of the ONH and posterior pole in highly myopic eyes were different based on the microstructure of β-PPA. Whether these features are linked to the development of glaucoma in myopic eyes should be investigated in future studies.

Association of macular thickness with parapapillary atrophy in myopic eyes

Background

To investigate whether macular structure could be affected by axial elongation and to determine the association between macular intraretinal thickness and the microstructure of β-zone parapapillary atrophy (PPA) in myopic eyes.

Methods

The study recruited 113 healthy myopic subjects (113 eyes). Images of the macula, subfoveal choroid, and optic nerve head were acquired using spectral-domain optical coherence tomography (SD-OCT). An automatic segmentation algorithm was used to segment the macular images into 7 intraretinal layers. PPA widths with and without Bruch’s membrane (PPA_+BM and PPA_-BM, respectively) were evaluated. Linear regression analysis was performed to evaluate the association between macular intraretinal thickness and axial length and the microstructure of PPA.

Results

An increase in axial length was associated with a decrease in whole macular thickness of the peripheral region and an increase in whole macular thickness of the central region. Thickness alterations of the macular intraretinal layers were most apparent in the peripheral region. A significant correlation was found between PPA_-BM width and macular intraretinal layer thickness, whereas no significant correlation was found between PPA_+BM width and macular intraretinal layer thickness. Moreover, both PPA_+BM and PPA_-BM widths significantly correlated with subfoveal choroidal thickness.

Conclusions

Macular intraretinal layer thickness may be affected by PPA_-BM width. These findings indicate that the microstructure of PPA should be considered when evaluating the macula in patient with myopia and glaucoma.

Peripapillary Choroidal Vascularity Index and Microstructure of Parapapillary Atrophy

Purpose

To investigate the association between the microstructure of β-zone parapapillary atrophy (βPPA) and choroidal vascularity index (CVI) determined by spectral-domain optical coherence tomography (SD-OCT) in glaucomatous eyes.

Methods

A total of 160 eyes of 160 primary open-angle glaucoma patients with βPPA were included. Total choroidal area (TCA), luminal area (LA), and CVI were measured at a 3.5-mm distance from the Bruch's membrane (BM) opening center by image binarization of SD-OCT B-scans. The widths of βPPA with BM (βPPA+BM) and without BM (βPPA-BM), and juxtapapillary choroidal thickness (JPCT) were measured on six radial SD-OCT images. OCT angiography-derived parapapillary deep-layer microvasculature dropout (MvD_P) was also derived.

Results

In the multivariate regression analysis, larger βPPA+BM was significantly associated with smaller TCA and smaller LA (P < 0.05, respectively), but not with CVI and JPCT (P > 0.05, respectively). Meanwhile, βPPA-BM was not significantly associated with TCA, LA, CVI, or JPCT in the multivariate regression analysis (P > 0.05).

Conclusions

Despite significant relationship between the choroidal thinning and larger βPPA+BM, choroidal vascularity was not associated with the βPPA+BM width. These findings suggest that the presumed common pathogenic mechanism between RPE atrophy and peripapillary choroidal thinning may not be mediated by the impaired choroidal perfusion in glaucomatous eyes. Future studies on the mechanisms in explaining the relationship between the atrophy of retinal pigment epithelium (RPE) and choroid in glaucoma are needed.

Exploring choroidal angioarchitecture in health and disease using choroidal vascularity index

The choroid is one of the most vascularized structures of the human body and plays an irreplaceable role in nourishing photoreceptors. As such, choroidal dysfunction is implicated in a multitude of ocular diseases. Studying the choroid can lead to a better understanding of disease pathogenesis, progression and discovery of novel management strategies. However, current research has produced inconsistent findings, partly due to the physical inaccessibility of the choroid and the lack of reliable biomarkers. With the advancements in optical coherence tomography technology, our group has developed a novel quantitative imaging biomarker known as the choroidal vascularity index (CVI), defined as the ratio of vascular area to the total choroidal area. CVI is a potential tool in establishing early diagnoses, monitoring disease progression and prognosticating patients. CVI has been reported in existing literature as a robust marker in numerous retinal and choroidal diseases. In this review, we will discuss the current role of CVI with reference to existing literature, and make postulations about its potential and future applications.

Bruch's membrane opening enlargement and its implication on the myopic optic nerve head

We examined the association between Bruch’s membrane opening (BMO) area and various ocular parameters and investigated the implication of BMO enlargement on the myopic optic nerve head. One hundred eighty-five myopic eyes were included in this cross-sectional study. Among the included eyes, 53 having axial lengths between 26 and 27 mm were further analyzed to investigate the association between BMO area and various ocular parameters. BMO area, BMO-minimum rim width (BMO-MRW), peripapillary choroidal thickness (pCT), width of β-parapapillary atrophy with and without Bruch’s membrane (PPA_+BM and PPA_−BM), and presence of lamina cribrosa (LC) defect were evaluated. We found that BMO area tended to increase with increasing axial length, but varied among the highly myopic eyes even though they had similar degrees of myopia. In the subgroup analysis of eyes with axial lengths between 26 and 27 mm, BMO area was highly variable and it significantly correlated with PPA_−BM width and temporal-inferior, nasal-inferior, and nasal BMO-MRW and pCT. LC defects were more common in myopic eyes with enlarged BMO. A multivariate regression model revealed that higher intraocular pressure, enlarged BMO, and thinner BMO-MRW were associated with LC defects in highly myopic eyes. These findings should be considered when evaluating myopic eyes.

Morphological features of parapapillary beta zone and gamma zone in chronic primary angle-closure glaucoma

PURPOSE

To investigate the morphological features of parapapillary beta zone and gamma zone and their associated factors in eyes with chronic primary angle-closure glaucoma (CACG).

METHODS

The observational cross-sectional study included 65 CACG eyes and 65 non-myopic control eyes. On enhanced depth imaging of optical coherent tomography images, the area of parapapillary beta zone and gamma zone, and the peripapillary choroidal thickness at 6 sectors were measured. The optic disc ovality index and Bruch's membrane opening (BMO) shape were further calculated.

RESULTS

Beta zone was present in 103 (79.2%) eyes and gamma zone in 29 (22.3%) eyes. Compared to control eyes, CACG was associated with larger parapapillary beta zone, female gender, and older age (P < 0.01). No significant difference was observed in axial length and peripapillary choroidal thickness between both groups (P > 0.05). In multivariate analysis, beta zone area was positively associated with older age and higher prevalence of CACG (P < 0.01), while a larger gamma zone area was associated with a smaller disc ovality index and a higher BMO ovality ratio (P < 0.01). The peripapillary choroidal thickness at six sectors was decreased with older age (P < 0.01).

CONCLUSIONS

In mainly non-myopic subjects with or without CACG, larger parapapillary beta zone was correlated with older age and presence of glaucoma, while a larger parapapillary gamma zone was correlated with disc ovality but not with glaucoma. Parapapillary beta zone and gamma zone may play different roles in physiological and glaucomatous changes around optic nerve head.

Deep-Layer Microvasculature Dropout by Optical Coherence Tomography Angiography and Microstructure of Parapapillary Atrophy

Purpose

To investigate the association between the microstructure of β-zone parapapillary atrophy (βPPA) and parapapillary deep-layer microvasculature dropout assessed by optical coherence tomography angiography (OCT-A).

Methods

Thirty-seven eyes with βPPA devoid of the Bruch's membrane (BM) (γPPA) ranging between completely absent and discontinuous BM were matched by severity of the visual field (VF) damage with 37 eyes with fully intact BM (βPPA+BM) based on the spectral-domain (SD) OCT imaging. Parapapillary deep-layer microvasculature dropout was defined as a dropout of the microvasculature within choroid or scleral flange in the βPPA on the OCT-A. The widths of βPPA, γPPA, and βPPA+BM were measured on six radial SD-OCT images. Prevalence of the dropout was compared between eyes with and without γPPA. Logistic regression was performed for evaluating association of the dropout with the width of βPPA, γPPA, and βPPA+BM, and the γPPA presence.

Results

Eyes with γPPA had significantly higher prevalence of the dropout than did those without γPPA (75.7% versus 40.8%; P = 0.004). In logistic regression, presence and longer width of the γPPA, worse VF mean deviation, and presence of focal lamina cribrosa defects were significantly associated with the dropout (P < 0.05), whereas width of the βPPA and βPPA+BM, axial length, and choroidal thickness were not (P > 0.10).

Conclusions

Parapapillary deep-layer microvasculature dropout was associated with the presence and larger width of γPPA, but not with the βPPA+BM width. Presence and width of the exposed scleral flange, rather than the retinal pigmented epithelium atrophy, may be associated with deep-layer microvasculature dropout.

Steeper structure-function relationship in eyes with than without a parapapillary deep-layer microvasculature dropout

The degree of visual field (VF) loss can vary widely at a given level of retinal nerve fiber layer (RNFL) thickness. The cause of this variability is not fully understood. This cross-sectional study investigated whether the presence of choroidal microvasculature dropout (MvD) influences on the structure-function relationship among glaucomatous eyes. Seventy-one primary open-angle glaucoma (POAG) patients with choroidal MvD as determined by optical coherence tomography angiography (MvD+ group), and 71 age- and inferotemporal (IT) RNFL thickness-matched POAG patients without MvD (MvD– group) were included. VF sensitivity within the region corresponding to the IT RNFL sector was averaged using the total and pattern deviation fields. The slope of log-scale RNFL thickness versus VF defect was significantly steeper for the MvD+ than the MvD– group, as determined by both total and pattern deviation maps (P = 0.004 and <0.001, respectively). Both total and pattern VF deviation were significantly worse in the MvD+ than in the MvD– group (P = 0.002 and 0.007, respectively). Same results were obtained in subgroup analyses for eyes with thick and thin RNFL thickness (all P ≤ 0.027). These data suggest that parapapillary MvD is associated with poorer function of the remaining axons in eyes with POAG.

Microstructure of Parapapillary Atrophy Is Associated With Parapapillary Microvasculature in Myopic Eyes

PURPOSE

To evaluate the clinical characteristics of beta-parapapillary atrophy (β-PPA) in myopic eyes and determine whether the microstructure of β-PPA is associated with parapapillary microvasculature by using optical coherence tomography (OCT) angiography.

DESIGN

Cross-sectional study.

METHODS

This study included 80 subjects with myopia with β-PPA. Spherical equivalent (SE) refractive error, axial length, horizontal tilt angle, and the width of β-PPA were evaluated. The microstructure of β-PPA and subfoveal choroidal thickness were evaluated using enhanced-depth imaging OCT and eyes were classified into 3 groups based on the presence of Bruch membrane (BM): a PPA_+BM-only group, a PPA_+BM and PPA_-BM group, and a PPA_-BM-only group. Superficial and deep parapapillary vessel density was measured using OCT angiography. Clinical characteristics were compared among the groups and linear regression analysis was performed to explore the relationship between the parapapillary microvasculature and microstructure of β-PPA.

RESULTS

The mean axial length and SE refractive error of the participants were 26.47 ± 1.17 mm and -6.28 ± 2.71 diopters, respectively. The PPA_+BM-only group had a more inferiorly rotated optic disc (P = .025), larger β-PPA (P < .001), and lower superficial and deep parapapillary vessel density (both P < .001) compared with those of the PPA_-BM-only group. Multivariate linear regression analysis showed that the average PPA_+BM width on horizontal scans was significantly associated with superficial and deep parapapillary vessel density (P = .034 and P = .003, respectively).

CONCLUSIONS

Significant differences were observed in the microvasculature according to the microstructure of β-PPA. PPA_+BM width was closely correlated with superficial and deep parapapillary vessel density. Longitudinal studies are needed to elucidate the role of β-PPA in the development and progression of glaucoma in myopic eyes.

Ocular and Clinical Characteristics Associated with the Extent of Posterior Lamina Cribrosa Curve in Normal Tension Glaucoma

Although normal-tension glaucoma (NTG) is pathogenetically heterogenous, there have been few attempts to subclassify NTG patients according to the mechanism and anatomy of optic nerve damage. This cross-sectional study was performed to investigate differences in the clinical and ocular characteristics between NTG patient groups stratified according to the degree of posterior lamina cribrosa (LC) curve which was assessed by calculating LC curvature index (LCCI). A total of 101 eyes of 101 treatment naïve NTG patients were included. The optic nerve head was imaged using enhanced-depth-imaging spectral-domain optical coherence tomography in three horizontal B-scan images in each eye. The patients were divided into two groups based on the magnitude of LCCI using a cutoff of known upper 95 percentile value in healthy subjects: a steeply curved LC group (Group 1, 75 eyes, 74.3%) and a relatively flat LC group (Group 2, 26 eyes, 25.7%). NTG eyes with relatively flat LC had lower intraocular pressure, and were associated with greater parapapillary structural alternation and systemic risk factors. These data suggest that assessment of LC morphology may help clinicians seek additional risk factors and make inferences about the mechanism of optic nerve damage in individual patients.

Topographic correlation between juxtapapillary choroidal thickness and parapapillary deep-layer microvasculature dropout in primary open-angle glaucoma

Purpose

To investigate the topographic relationship between parapapillary deep-layer microvasculature dropout (MvD) as assessed by optical coherence tomography (OCT) angiography (OCTA) and the juxtapapillary choroidal thickness (JPCT) in primary open-angle glaucoma (POAG).

Methods

A total of 194 eyes (138 POAG and 56 control eyes) having parapapillary atrophy (PPA) were imaged using the swept-source OCT and OCTA to examine the microstructure of PPA and measure the JPCT, and to determine the presence of the MvD. MvD was defined as a focal sectoral capillary dropout without any visible microvascular network identified in the parapapillary deep-layer in the en face OCTA images.

Results

JPCT was smaller in the POAG group than control group at 6-, 6.5-, 7- and 7.5-o’clock meridians (all p≤0.002). When POAG eyes were classified into those with parapapillary γ-zone and those with only β-zone without γ-zone, the mean JPCT was significantly smaller in the latter (p=0.027). The JPCT differed between with and without MvD only in eyes with a γ-zone: the JPCT was smaller in the eyes having MvD at 7- and 7.5-o’clock meridians (both p=0.001), where MvD was detected most frequently. However, such a difference was not observed in the eyes with only β-zone without the γ-zone at any of the meridians.

Conclusions

Localised reductions in JPCT were observed at the location of MvD in POAG eyes with parapapillary γ-zone. Such a correlation was not observed in the POAG eyes with only β-zone, but the mean JPCT was significantly smaller in this group.

Assessment of peripapillary choroidal thickness in primary open-angle glaucoma patients with choroidal vascular prominence

PURPOSE

To investigate the relationship between peripapillary choroidal thickness (PCT) and choroidal vascular prominence (CVP) colocalized with retinal nerve fiber layer (RNFL) defect in primary open-angle glaucoma (POAG) eyes and to evaluate the relationship between PCT and POAG severity.

METHODS

In this cross-sectional comparative study, 29 POAG patients with CVP on RNFL imaging (Group A), 70 POAG patients without CVP (Group B) and 63 healthy controls (Group C) were examined. Various factors including age, intraocular pressure (IOP), spherical equivalent (SE), axial length (AXL), central corneal thickness (CCT), peripapillary RNFL thickness, visual-field mean deviation (MD) and pattern standard deviation (PSD) were investigated. Also, PCT (average, clock-hour) was measured by swept-source optical coherence tomography. The differences in each of the factors were analyzed among the groups.

RESULTS

There was no significant difference in age, IOP, SE, AXL or CCT among the three groups (P > 0.05). MD, PSD and RNFL thickness (RNFLT) in Groups A and B were lower than in Group C, but there was no difference between Groups A and B. There was a significant difference in adjusted PCT between Groups A and B (79.39 ± 6.56 vs. 115.87 ± 4.25, P < 0.001). Every adjusted clock-hour PCT in Group A was significantly thinner than in Group B.

CONCLUSIONS

CVP in red-free RNFL images indicated severe thinning of PCT. Although PCT thinning was not related to glaucoma severity, CVP in red-free RNFL images should be observed as an indicator of PCT thinning, associated with POAG.