Effect of Adjusting Retinal Nerve Fiber Layer Profile to Fovea-Disc Angle Axis on the Thickness and Glaucoma Diagnostic Performance

Evaluation of the Diagnostic Capability of Spectralis SD-OCT 8 × 8 Posterior Pole Software with the Grid Tilted at 7 Degrees and Horizontalized in Glaucoma

Background: The goal was to evaluate the diagnostic capability of different parameters obtained with the posterior pole (PP) software in Spectralis SD-OCT with the 8 × 8 grid tilted at 7° and horizontalized in glaucomatous eyes. Methods: A total of 299 eyes were included, comprising 136 healthy eyes and 163 with primary open-angle glaucoma (POAG). The following segmentations were evaluated: complete retina, retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), GCL and inner plexiform layer (GCLIPL), ganglion cell complex (GCC), outer plexiform layer and outer nuclear layer (OPLONL), inner retinal layer (IRL), and outer retinal layer (ORL). Different patterns of macular damage were represented using heatmaps for each studied layer, where the areas under the curve (AUROC) values and a retinal thickness cutoff point were defined to discriminate POAG patients. Results: There was not any difference in the diagnostic capability for detecting glaucoma between the grid tilted at 7° and horizontalized. The macular segmentations that offer the highest diagnostic ability in glaucoma discrimination were, in the following order, RNFL (AUROC = 0.796), GCC (AUROC = 0.785), GCL (AUROC = 0.784), GCLIPL (AUROC = 0.770), IRL (AUROC = 0.755), and the complete retina (AUROC = 0.752). In contrast, ORL and OPLONL do not appear to be helpful for discriminating POAG. Conclusions: Some results of PP software may be useful for discriminating POAG.

Clinical Use of PanoMap for Glaucoma: Frequently Damaged Areas in Early Glaucoma

PRCIS

Recognizing the shortcomings of poor consistency of the fovea-disc relationship at different time points and comparing PanoMaps may well facilitate the understanding of the spatial relationship between parapapillary and macular areas in glaucoma.

PURPOSE

The aims of this study are to analyze the spatial distribution of the frequently damaged areas in early glaucoma, compare the patterns between nonprogressors and progressors using the combined wide-field parapapillary and macular deviation maps (PanoMap), and to evaluate the consistency of the fovea-disc relationship in PanoMap. The fovea-disc distance (FDD) and fovea-disc axis (FDA) were compared at baseline and at the last follow-up.

MATERIALS AND METHODS

In total, 118 patients with early glaucoma and a minimum follow-up period of 3 years were included in this retrospective observational study. The pattern of structural changes was evaluated by averaging the PanoMaps of the enrolled patients at baseline and last follow-up. Longitudinal comparison of the FDD and FDA was performed at baseline and the last follow-up. Patients were divided into nonprogressor (n=44) and progressor (n=74), and the patterns of glaucoma progression in PanoMaps were compared between them.

RESULTS

At baseline, the glaucomatous damage was found more frequently in the macular compared with the parapapillary area. The spatial distribution of frequently damaged areas was similar between the nonprogressor and progressor. At the last follow-up, compared with the baseline structural change on the PanoMap, the progressive structural changes extended toward the fovea at both the parapapillary and macular areas in the progressor. The FDD and FDA were significantly different between the baseline and the last follow-up.

CONCLUSIONS

The PanoMaps showed a clear spatial distribution of early glaucomatous changes, indicating that the damaged area was frequently observed in the macular area. As the consistency of the fovea-disc relationship in PanoMaps was not excellent, this aspect should be considered when interpreting the PanoMap.

A Wide-Field Optical Coherence Tomography Normative Database Considering the Fovea-Disc Relationship for Glaucoma Detection

Purpose

One purpose of this study was to collect wide-field swept-source optical coherence tomography (SS-OCT) data from healthy eyes and build a wide-filed normative database. Another purpose was to compare the glaucoma diagnostic ability of new parameters based on this normative database to the parameters that are currently in use, such as the peripapillary retinal nerve fiber layer (RNFL), macular ganglion cell-inner plexiform layer, and ganglion cell complex (GCC) thickness.

Methods

This study had 220 healthy eyes and 292 eyes with early-stage glaucoma (EG) and moderate-stage glaucoma (MG) enrolled. Using the wide-field SS-OCT images (12 × 9 mm) of healthy eyes, a wide-field normative database was constructed by transforming and combining the individual images into a uniform template using the fovea and optic disc centers as fixed landmarks. Adjustment for the disc size was conducted. With this normative database, new parameters based on the ratio of the fovea-disc distance (FDD) consisting of the fovea-disc relationship were evaluated. The glaucoma diagnostic ability was assessed based on the area under the receiver operating characteristic curve (AUC).

Results

Among the new peripapillary parameters, the RNFL of the circumference of the circle with diameter 0.8 FDD showed the highest AUC value for EG and MG, but the value was not significantly superior to that of the initial RNFL (AUC = 0.940 vs. 0.937, P = 0.631). Among the macular parameters, the GCC of the area of the circle of 1.5 FDD showed the highest AUC value for EG and MG, and the value was significantly superior to that of initial GCC (AUC = 0.929 vs. 0.919, P = 0.033). However, there was no significant difference between the initial and adjusted GCC thickness in patients included in the EG or MG groups separately.

Conclusions

A wide-field normative database was built to consider the relationship between the fovea and the optic disc. Considering this aspect, we found that the GCC analysis using a broader area presented a significantly greater glaucoma diagnostic performance for EG and MG in the macula than the initial parameter for the GCC.

Translational Relevance

Based on this wide-field normative database, the clinical use of a wide-field deviation map may help diagnose the patients with EG and MG in the future.

Neural Network-Based Retinal Nerve Fiber Layer Profile Compensation for Glaucoma Diagnosis in Myopia: Model Development and Validation

Background

Due to the axial elongation–associated changes in the optic nerve and retina in high myopia, traditional methods like optic disc evaluation and visual field are not able to correctly differentiate glaucomatous lesions. It has been clinically challenging to detect glaucoma in highly myopic eyes.

Objective

This study aimed to develop a neural network to adjust for the dependence of the peripapillary retinal nerve fiber layer (RNFL) thickness (RNFLT) profile on age, gender, and ocular biometric parameters and to evaluate the network’s performance for glaucoma diagnosis, especially in high myopia.

Methods

RNFLT with 768 points on the circumferential 3.4-mm scan was measured using spectral-domain optical coherence tomography. A fully connected network and a radial basis function network were trained for vertical (scaling) and horizontal (shift) transformation of the RNFLT profile with adjustment for age, axial length (AL), disc-fovea angle, and distance in a test group of 2223 nonglaucomatous eyes. The performance of RNFLT compensation was evaluated in an independent group of 254 glaucoma patients and 254 nonglaucomatous participants.

Results

By applying the RNFL compensation algorithm, the area under the receiver operating characteristic curve for detecting glaucoma increased from 0.70 to 0.84, from 0.75 to 0.89, from 0.77 to 0.89, and from 0.78 to 0.87 for eyes in the highest 10% percentile subgroup of the AL distribution (mean 26.0, SD 0.9 mm), highest 20% percentile subgroup of the AL distribution (mean 25.3, SD 1.0 mm), highest 30% percentile subgroup of the AL distribution (mean 24.9, SD 1.0 mm), and any AL (mean 23.5, SD 1.2 mm), respectively, in comparison with unadjusted RNFLT. The difference between uncompensated and compensated RNFLT values increased with longer axial length, with enlargement of 19.8%, 18.9%, 16.2%, and 11.3% in the highest 10% percentile subgroup, highest 20% percentile subgroup, highest 30% percentile subgroup, and all eyes, respectively.

Conclusions

In a population-based study sample, an algorithm-based adjustment for age, gender, and ocular biometric parameters improved the diagnostic precision of the RNFLT profile for glaucoma detection particularly in myopic and highly myopic eyes.

Assessment of objective ocular cyclodeviation under monocular condition and binocular condition using fundus photography

Objective

The relationship between retinal structure and function of glaucomatous eyes has attracted a great deal of research attention. However, visual field tests are conducted under monocular condition, and ophthalmic imaging was performed in patients without occlusion. We aimed to assess the objective ocular cyclodeviation between monocular occlusion and binocular conditions using fundus photography.

Methods and analysis

This study included 76 healthy participants. We obtained six photos of the right eye of each patient using fundus photography. Three of the photographs were taken under monocular conditions, and the other three, under binocular conditions. We measured the optic disc margin-fovea angle (MFA) of the line connecting one point of the disc limbus and the fovea. One-way repeated analysis of variance was used to compare the angles under both conditions. We also examined the direction of ocular rotation under the binocular condition regarding the monocular condition.

Results

The MFAs were 12.12°±3.83° and 12.19°±3.95° under the monocular and binocular conditions, respectively. There was no significant difference in both MFAs (F=1.19, p=0.28). The mean cyclodeviation was 0.07°±0.80° (range: −2.40° to +2.75°). A total of 38 eyes showed excycloduction, while another 38 showed incycloduction.

Conclusion

Significant cyclodeviation did not occur regardless of the existence of an occlusion. When examining the relationship between retinal structure and function, the difference in rotation angle under both conditions need not be taken into consideration if the other disease did not cause pathological cyclodeviation.

Anatomical Location of the Raphe and Extended Raphe in the Human Retina: Implications for Assessment of the Optic Nerve with OCT

Purpose

To determine the location of (1) the superior–inferior watershed between the fovea and optic disc (extended raphe) at the peripapillary optical coherence tomography (OCT) measurement circle and (2) the raphe, temporal to the fovea.

Methods

We used existing data consisting of 2285 traced retinal nerve fiber bundle trajectories from 83 fundus images. For localization of the extended raphe at the 3.46-mm-diameter OCT measurement circle, trajectories were classified as belonging to the superior or inferior hemiretina, using predefined criteria. For the raphe, we localized the endings of trajectories coming from the superior and inferior arcuate bundles.

Results

At the measurement circle, the extended raphe is located 14° (range, 12°–16°) inferiorly to a horizontal line through the optic disc center. The raphe follows a horizontal line at the latitude of the fovea if the disc is assumed to be located 15° nasal to and 2° above the fovea.

Conclusions

At the measurement circle, OCT brands use either the 9 o'clock location or a straight line connecting the center of the optic disc and the fovea as a reference for separating the hemiretinas. This results, on average, in a 14° and 6° misalignment with respect to the anatomical watershed, respectively. For the macular area, the commonly used line through the center of the optic disc and the fovea fails to describe the raphe adequately.

Translational Relevance

An unbiased asymmetry assessment of the optic nerve requires a detailed knowledge of the shape and location of the (extended) raphe.

Vulnerability Zone of Glaucoma Progression in Combined Wide-field Optical Coherence Tomography Event-based Progression Analysis

Purpose

To investigate the spatial characteristics and patterns of structural progression using the combined retinal nerve fiber layer (RNFL) and ganglion cell–inner plexiform layer event-based progression analysis feature provided by the Guided Progression Analysis (GPA) software of spectral-domain optical coherence tomography.

Methods

In this retrospective observational study, we evaluated 89 patients with open-angle glaucoma showing clinically confirmed structural progression within a minimum follow-up period of 3 years. For each eye, the RNFL and ganglion cell–inner plexiform layer GPA data were extracted from serial spectral-domain optical coherence tomography (HD-OCT 4000, Carl Zeiss Meditec, Inc., Dublin, CA) data from 2012 to 2017 (available in commercial report). A combined wide-field GPA map was merged using vascular landmark-guided superimposition of RNFL and ganglion cell–inner plexiform layer GPA event-based progression maps onto the RNFL image (resulting in the GPA PanoMaps: proposed in this study). The pattern of progressive structural changes was evaluated by comparing the baseline combined wide-field OCT deviation maps (PanoMap deviation maps: available in commercial report) and GPA PanoMaps at the time the first progression was detected and the GPA PanoMaps at the last follow-up. Spatial characteristics and patterns of glaucoma structural progression on GPA PanoMaps were evaluated.

Results

Progressive structural progression was detected most frequently at the macular vulnerability zone (MVZ), with the peripapillary and macular progression being well-correlated spatially. Compared with the baseline structural change on PanoMap, the progressive structural changes extended toward the fovea at both the peripapillary and macular areas. A spatial difference was observed between the areas where structural damage was frequently found on PanoMap (peripapillary inferoinferior sector and macular MVZ) and areas where progression was frequently found on GPA PanoMap (peripapillary and macular MVZ).

Conclusions

The patterns of progressive glaucomatous structural changes in both the peripapillary and macular areas were confirmed on the combined wide-field GPA map (GPA PanoMap). An analysis of the progression pattern using the GPA PanoMap facilitates the understanding of the spatial relation between the peripapillary and macular areas in glaucoma.

Microvascular damage assessed by optical coherence tomography angiography for glaucoma diagnosis: a systematic review of the most discriminative regions

A growing number of studies have reported a link between vascular damage and glaucoma based on optical coherence tomography angiography (OCTA) imaging. This multitude of studies focused on different regions of interest (ROIs) which offers the possibility to draw conclusions on the most discriminative locations to diagnose glaucoma. The objective of this work was to review and analyse the discriminative capacity of vascular density, retrieved from different ROIs, on differentiating healthy subjects from glaucoma patients. PubMed was used to perform a systematic review on the analysis of glaucomatous vascular damage using OCTA. All studies up to 21 April 2019 were considered. The ROIs were analysed by region (macula, optic disc and peripapillary region), layer (superficial and deep capillary plexus, avascular, whole retina, choriocapillaris and choroid) and sector (according to the Garway-Heath map). The area under receiver operator characteristic curve (AUROC) and the statistical difference (p-value) were used to report the importance of each ROI for diagnosing glaucoma. From 96 screened studies, 43 were eligible for this review. Overall, the peripapillary region showed to be the most discriminative region with the highest mean AUROC (0.80 ± 0.09). An improvement of the AUROC from this region is observed when a sectorial analysis is performed, with the highest AUROCs obtained at the inferior and superior sectors of the superficial capillary plexus in the peripapillary region (0.86 ± 0.03 and 0.87 ± 0.10, respectively). The presented work shows that glaucomatous vascular damage can be assessed using OCTA, and its added value as a complementary feature for glaucoma diagnosis depends on the region of interest. A sectorial analysis of the superficial layer at the peripapillary region is preferable for assessing glaucomatous vascular damage.

Effect of Foveal Location on Retinal Nerve Fiber Layer Thickness Profile in Superior Oblique Palsy Eyes

PRéCIS:: Superior oblique palsy (SOP) eyes show thinner inferotemporal retinal nerve fiber layer (RNFL) without adjusting for foveal position. There was a strong correlation between the degree of torsion and the difference in the RNFL thickness before and after adjusting foveal location.

PURPOSE

The impact of foveal position on RNFL thickness has been shown. In this study, we evaluate RNFL thickness profiles according to the disc-foveal angle in SOP and control eyes.

MATERIALS AND METHODS

In 44 eyes of 22 patients with unilateral congenital SOP and 42 eyes of 42 normal controls, the position of the fovea relative to the optic disc was calculated by optical coherence tomography using FoDi (fovea-to-disc) technology. After measuring RNFL thickness with FoDi alignment technology, each optical coherence tomography image was reevaluated with FoDi turned off, and the measurements were repeated to determine RNFL values according to the disc-foveal angle.

RESULTS

The average disc-foveal angle was -10.85±6.60 degrees and -10.71±6.63 degrees in the affected and fellow eyes of SOP patients; these values were significantly greater than control subjects (-5.88±4.09 degrees). There was no significant difference in RNFL sector values between SOP and control eyes with FoDi. From all RNFL sectors, the measured inferotemporal thickness was less in SOP eyes without FoDi than in SOP eyes with FoDi (129.7±20.5 µm vs. 144.6±17.8 µm, respectively, P=0.001). Differences of the RNFL thicknesses with and without FoDi in SOP eyes in the superotemporal and inferotemporal sectors were 5.40±13.42 and 14.84±15.00, respectively, which were significantly more than the same changes in control eyes with amount of 0.30±6.57 and 8.52±10.4 (P=0.02 for both sectors).

CONCLUSIONS

In SOP eyes with large amounts of torsion, a correction for the disc-foveal angle is necessary for accurate determination of the RNFL thickness profile.

Macular imaging with optical coherence tomography in glaucoma

With the advent of spectral-domain optical coherence tomography, imaging of the posterior segment of the eye can be carried out rapidly at multiple anatomical locations, including the optic nerve head, circumpapillary retinal nerve fiber layer, and macula. There is now ample evidence to support the role of spectral-domain optical coherence tomography imaging of the macula for detection of early glaucoma. Macular spectral-domain optical coherence tomography measurements demonstrate high reproducibility, and evidence on its utility for detection of glaucoma progression is accumulating. We present a comprehensive review of macular spectral-domain optical coherence tomography imaging emerging as an essential diagnostic tool in glaucoma.

Effects of Age on Peripapillary and Macular Vessel Density Determined Using Optical Coherence Tomography Angiography in Healthy Eyes

Purpose

To evaluate the effect of age on global and sectoral vascular parameters of the peripapillary area and macula in healthy eyes by using optical coherence tomography angiography (OCT-A).

Methods

This retrospective cross-sectional study included 239 eyes of 172 healthy subjects. Subjects were scanned using the high-definition disc angio scan (4.5 × 4.5 mm), retina angio scan (6 × 6 mm), and optic nerve head/ganglion cell complex (GCC) modes of OCT-A. Global and sectoral circumpapillary vessel density (VD), parafoveal VD, retinal nerve fiber layer (RNFL), and GCC thickness parameters were modeled in terms of age by using linear mixed-effect models incorporating covariates. Normalized slopes were calculated by dividing the absolute slopes by the mean value of the OCT-A parameters.

Results

All global and sectoral circumpapillary VDs decreased significantly with increasing age, except for those in the temporal superior sector. The steepest slopes in the circumpapillary region were observed in nasal superior (-0.098%/y) and nasal inferior (-0.096%/y) sectors. The global, temporal, and superior macular VDs also decreased with increasing age, while the foveal, nasal, and inferior parameters did not. The temporal quadrant showed the steepest slope among the macular parameters (-0.068%/y). The RNFL and GCC thickness results showed similar trends.

Conclusions

Age substantially affected VD in most of the peripapillary and macular areas; however, the papillomacular bundle area did not show significant age-related vascular changes. These age-related global and sectoral differences in circumpapillary and macular VDs should be considered when assessing pathologic VD changes over time.

Serial Combined Wide-Field Optical Coherence Tomography Maps for Detection of Early Glaucomatous Structural Progression

Importance

Both parapapillary and macular areas are important in determining the progression of early glaucoma. However, no attempt has been made to assess the progression of glaucoma in images that combine the 2 areas.

Objective

To evaluate the potential usefulness of serial analysis of combined wide-field optical coherence tomography (OCT) maps for detection of structural progression in patients with early glaucoma.

Design, Setting, and Participants

Retrospective observational study. Patients with early primary open-angle glaucoma with a minimum of 3-year follow-up involving serial spectral-domain OCT measurement were analyzed. Patients were divided into a nonprogressor group (n = 47) and a progressor group (n = 47) on the basis of serial stereo disc photography and red-free photography. Serial combined wide-field OCT maps integrating parapapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) maps were generated with the embedded software of serial spectral-domain OCT. Glaucoma specialists then assessed the structural progression detection ability of those serial wide-field OCT maps for early glaucomatous eyes and compared their sensitivity with those of RNFL and GCIPL guided progression analyses (GPAs).

Main Outcomes and Measures

The diagnostic ability of the serial wide-field OCT maps for early glaucomatous structural progression.

Results

Ninety-four patients (mean [SD] age, 51.4 [12.3] years; 48 [51.1%] women; all Korean) were included. The serial wide-field OCT map analysis showed good agreement for detection of structural progression between the 2 glaucoma graders (wide-field OCT thickness map: κ = 0.649; wide-field OCT deviation map: κ = 0.833). These maps showed early glaucomatous structural progression detection abilities comparable with those of RNFL and GCIPL GPAs (sensitivities of wide-field OCT thickness map, wide-field OCT deviation map, RNFL GPA, and GCIPL GPA = 63.8%, 83.0%, 83.0%, and 66.0%, respectively, all P > .05; specificities of wide-field OCT thickness map, wide-field OCT deviation map, RNFL GPA, and GCIPL GPA = 93.6%, 95.7%, 84.8%, and 93.6%, respectively, all P > .05).

Conclusions and Relevance

The serial combined wide-field OCT maps integrating RNFL and GCIPL maps performed well in detecting structural progression in early glaucomatous eyes. Confirmation in an independent prospective study might provide greater confidence in this conclusion.

Combined Use of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Event-based Progression Analysis

PURPOSE

To evaluate patterns of glaucomatous structural progression using the combined retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) event-based progression analysis feature provided by spectral-domain optical coherence tomography (SD-OCT)'s - (GPA) software.

DESIGN

Retrospective observational case series.

METHODS

Seventy-nine (79) patients were identified with open-angle glaucoma (OAG) showing clinically confirmed structural progression within a minimum 3-year follow-up period. For each eye, RNFL and GCIPL GPA data were obtained from serial SD-OCT data from 2012 to 2017. An integrated GPA map thereafter was merged by vascular landmark-guided superimposition of RNFL and GCIPL GPA event-based progression maps onto the RNFL imagery (resulting in what we call the GPA PanoMap). The GPA PanoMap progression patterns were classified as (1) RNFL-only, (2) GCIPL-only, (3) concurrent (both RNFL and GCIPL), (4) GCIPL after RNFL, and (5) RNFL after GCIPL. The locations of structural progression were classified, based on an earlier schematic model, as (1) superior vulnerability zone (SVZ), (2) papillomacular bundle (PM), (3) macular vulnerability zone (MVZ), and (4) inferoinferior portion. Structural progression patterns on the GPA PanoMap were evaluated according to the location of progression. Among the eyes with progression in the inferior hemiretina, structural progression patterns on the GPA PanoMap were evaluated according to the baseline structural damage.

RESULTS

On the GPA PanoMap, when structural progression was located in the SVZ or inferoinferior portion, it was detected only in the RNFL area; when progression was located in the PM or MVZ, various patterns were observed, among which the concurrent pattern was the majority in both areas (43.8% and 45.6% in the PM and MVZ, respectively). Among the eyes with progression in the inferior hemiretina (n = 66), the location of progression varied but did not differ significantly according to the baseline deviation map (P = .440). The progression patterns of MVZ were significantly different among the baseline deviation map patterns (P = .023); however, all of the progression patterns of the inferoinferior portion were RNFL-only.

CONCLUSION

The various progression patterns were confirmed according to the locations and baseline patterns of glaucomatous structural change on the integrated GPA map (GPA PanoMap). Combined use of RNFL and GCIPL GPA or the GPA PanoMap could be useful for determination of structural progression and understanding of its patterns in patients with glaucoma.

Age-related change and sex difference over 60s in disc-fovea angle in Japanese population: the Nagahama Study

PURPOSE

To analyse the disc-fovea angle (DFA) by age group and to compare sex differences in each age group in a large cohort population.

METHODS

This community-based cross-sectional cohort study included 9682 eyes of 9682 volunteers (aged 30-75 years). We measured the DFA, which is the angle between a horizontal line and a line connecting the fovea with the centroid of an optic disc on fundus photographs of the right eye. We manually marked the fovea and surrounded the optic disc. The centroid of an optic disc and the DFA was automatically calculated using originally developed software. We compared the DFA between age groups in 10-year increments and investigated sex differences of DFA in each age group.

RESULTS

Overall mean DFA was 6.32 ± 3.53°. The DFA of older subjects was significantly larger than that of younger subjects (p < 0.001). The DFA of women was larger than that of men in their 60s and 70s (p < 0.001 for both), but not in subjects in their 30s, 40s and 50s.

CONCLUSION

Larger DFA in women than in men in their 60s and 70s suggests the possibility that age-related excyclo-shift occurs more easily in postmenopausal women compared to men of the same age.

Does Foveal Position Relative to the Optic Disc Affect Optical Coherence Tomography Measurements in Glaucoma?

Objectives:

To determine interindividual variability in the angle between the anatomic axis connecting the fovea and optic disc center and the horizontal meridian using spectral domain optical coherence tomography (OCT).

Materials and Methods:

A total of 260 eyes of 133 subjects (81 women, 52 men) with glaucoma or suspected glaucoma were included in the study retrospectively. Fovea-disc angle (FoDi angle) measurements, determined as the angle between the horizontal meridian passing through the Bruch’s membrane opening (BMO) center and the line connecting the fovea and BMO center, were recorded from spectral domain-OCT scans performed by the same investigator. FoDi angle was defined as negative if the fovea was located below the horizontal meridian through the BMO center and positive if the fovea was located above it.

Results:

The mean age of the participants was 56.5±14.6 years (27-83 years). The mean FoDi angle was -6.43±4.96° (range: -24.40° to +11.60°). Absolute deviation of the fovea BMO axis from the horizontal axis was 0-5° in 83 eyes (31.92%), 5-10° in 124 eyes (47.69%), 10-15° in 41 eyes (15.76%), 15-20° in 10 eyes (3.84%), and greater than 20° in 2 eyes (0.79%).

Conclusion:

Most OCT devices currently used in the treatment and follow-up of glaucoma patients provide peripapillary retinal nerve fiber layer (RNFL) thickness measurements that are made based on a clinical axis in reference to the horizontal meridian passing through the optic disc center. The results of our study reveal interindividual variation in FoDi angle as well as intraindividual differences in FoDi angle between fellow eyes in the same individual. Disparity between clinical and anatomic quadrants could impact RNFL thickness measurements, which may lead to errors in the diagnosis of glaucoma.

Quantitative automated circumpapillary microvascular density measurements: a new angioOCT-based methodology

PURPOSE

To develop a new methodology to detect glaucoma damage based on circumpapillary microvascular density (cpmVD) as measured by optical coherence tomography angiography (angioOCT).

METHODS

AngioOCT scans from a random eye of 40 healthy subjects (aged 63 ± 14 years) and 82 glaucoma patients (aged 66 ± 9 years with an average visual field loss of -7.8 ± 6.5 dB) were used to develop a new angioOCT evaluation methodology. Optic disc-centred 3 × 3 mm images were collected (Angioplex^®, Zeiss Cirrus 5000 HD-OCT). An annular area with an inner radius of 1.16 mm and outer radius of 1.44 mm was chosen as the region of interest (ROI), with cpmVD calculated through lower envelope modulation avoiding the influence of the major retinal vessels. Additionally, the cpmVD and the microvascular density (mVD), stratified by sectors, were compared with the respective retinal nerve fibre layer (RNFL) thickness.

RESULTS

A significantly lower cpmVD was observed in the glaucoma group, for all visual field sectors (p < 0.001), when comparing to the healthy group. The inferior and superior mVD sectors showed the largest differences between groups. Moreover, glaucoma was linked to a reduction of cpmVD variation when compared to the healthy group. Lastly, a comparison between two healthy subgroups showed that the method is not biased by the presence of slight movement artefacts, optic disc dimensions and vessel crowding (p > 0.05).

CONCLUSIONS

The presented open-source methodology provides a robust quantitative analysis of the 360˚ mVD. It shows that cpmVD, and mVD sectors measured by angioOCT, can be used in everyday glaucoma practice.

Effect of optic disc-fovea distance on the normative classifications of macular inner retinal layers as assessed with OCT in healthy subjects

Purpose

To determine the influence of the optic disc–fovea distance (DFD) on the normative classifications based on thickness measurements of macular inner retinal layers with spectral-domain optical coherence tomography (OCT) in healthy subjects.

Methods

A total of 182 eyes from 182 healthy subjects were included (mean (SD) spherical equivalent −0.8 (1.9) dioptres). We performed macula and optic disc imaging with the Topcon 3D OCT 2000. The thickness of the macular inner retinal layers (macular retinal nerve fibre layer (mRNFL), ganglion cell-inner plexiform layer (GCIPL) and both combined (ganglion cell complex; GCC)) and the corresponding classifications based on the built-in normative database were recorded. The occurrence of an abnormal normative classification (occurrence of any thickness variable below the fifth percentile) was related to the DFD and other factors (axial length/refraction, optic disc area, fovea–disc angle, age, gender, image quality, visual field mean deviation and peripapillary retinal nerve fibre layer thickness), using logistic regression.

Results

The mean (SD) DFD was 4.90 (0.29) mm. A greater DFD was associated with a higher percentage of abnormal normative classification in the OCT parameters describing the thickness of the mRNFL (OR (95%CI) per 0.1 mm increase in DFD: 1.30 (1.13 to 1.50), p<0.001), GCIPL (1.18 (1.02 to 1.38), p=0.023) and GCC measurement (1.29 (1.08 to 1.55), p=0.006).

Conclusions

Eyes with a greater DFD are prone to false-positive classifications in the thickness assessment of the macular inner retinal layers. The thicknesses should always be interpreted in the context of DFD.

The Interrelationship between Refractive Error, Blood Vessel Anatomy, and Glaucomatous Visual Field Loss

Purpose

We quantified the interrelationship between retinal blood vessel (BV) anatomical variation, spherical equivalent (SE) of refractive error, and functional diagnostic parameters in glaucoma to identify optimal parameters for the improvement of optical coherence tomography (OCT) retinal nerve fiber layer thickness (RNFLT) norms.

Methods

A trained observer marked the intersections of the main superior/inferior temporal arteries and veins with concentric circles around the optic nerve head (ONH) center on fundus images. The interrelationship of BV, SE, and visual field global parameters was analyzed by multivariate regression and model comparison.

Results

A total of 445 eyes of 445 patients in a large glaucoma practice were selected. Of all investigated BV parameters, interartery angles (IAA) between superior and inferior arteries at a radius of 1.73 mm around the ONH center demonstrated the strongest relationship to SE (Bayesian information criterion difference to null model, 11.9). SE and BV parameters are unrelated to functional parameters, including mean deviation (MD), pattern standard deviation, and glaucoma hemifield test results.

Conclusions

BV locations outside the ONH are sufficiently stable over glaucoma severity to represent individual eye anatomy, and the IAA at 1.73 mm eccentricity is the optimal parameter to be considered for novel OCT RNFLT norms.

Translational Relevance

Among a large set of BV location parameters, considering IAA may improve RNFLT norms optimally and thereby increase the accuracy of clinical glaucoma diagnosis.

Enhanced Diagnostic Capability for Glaucoma of 3-Dimensional Versus 2-Dimensional Neuroretinal Rim Parameters Using Spectral Domain Optical Coherence Tomography

PURPOSE

To compare the diagnostic capability of 3-dimensional (3D) neuroretinal rim parameters with existing 2-dimensional (2D) neuroretinal and retinal nerve fiber layer (RNFL) thickness rim parameters using spectral domain optical coherence tomography (SD-OCT) volume scans.

MATERIALS AND METHODS

Design: Institutional prospective pilot study.

STUDY POPULATION

65 subjects (35 open-angle glaucoma patients, 30 normal patients).

OBSERVATION PROCEDURES

One eye of each subject was included. SD-OCT was used to obtain 2D RNFL thickness values and 5 neuroretinal rim parameters [ie, 3D minimum distance band (MDB) thickness, 3D Bruch's membrane opening-minimum rim width (BMO-MRW), 3D rim volume, 2D rim area, and 2D rim thickness].

MAIN OUTCOME MEASURES

Area under the receiver operating characteristic curve values, sensitivity, and specificity.

RESULTS

Comparing all 3D with all 2D parameters, 3D rim parameters (MDB, BMO-MRW, rim volume) generally had higher area under the receiver operating characteristic curve values (range, 0.770 to 0.946) compared with 2D parameters (RNFL thickness, rim area, rim thickness; range, 0.678 to 0.911). For global region analyses, all 3D rim parameters (BMO-MRW, rim volume, MDB) were equal to or better than 2D parameters (RNFL thickness, rim area, rim thickness; P-values from 0.023 to 1.0). Among the three 3D rim parameters (MDB, BMO-MRW, and rim volume), there were no significant differences in diagnostic capability (false discovery rate >0.05 at 95% specificity).

CONCLUSIONS

3D neuroretinal rim parameters (MDB, BMO-MRW, and rim volume) demonstrated better diagnostic capability for primary and secondary open-angle glaucomas compared with 2D neuroretinal parameters (rim area, rim thickness). Compared with 2D RNFL thickness, 3D neuroretinal rim parameters have the same or better diagnostic capability.

Impact of Natural Blind Spot Location on Perimetry

We study the spatial distribution of natural blind spot location (NBSL) and its impact on perimetry. Pattern deviation (PD) values of 11,449 reliable visual fields (VFs) that are defined as clinically unaffected based on summary indices were extracted from 11,449 glaucoma patients. We modeled NBSL distribution using a two-dimensional non-linear regression approach and correlated NBSL with spherical equivalent (SE). Additionally, we compared PD values of groups with longer and shorter distances than median, and larger and smaller angles than median between NBSL and fixation. Mean and standard deviation of horizontal and vertical NBSL were 14.33° ± 1.37° and −2.06° ± 1.27°, respectively. SE decreased with increasing NBSL (correlation: r = −0.14, p < 0.001). For NBSL distances longer than median distance (14.32°), average PD values decreased in the upper central (average difference for significant points (ADSP): −0.18 dB) and increased in the lower nasal VF region (ADSP: 0.14 dB). For angles in the direction of upper hemifield relative to the median angle (−8.13°), PD values decreased in lower nasal (ADSP: −0.11 dB) and increased in upper temporal VF areas (ADSP: 0.19 dB). In conclusion, we demonstrate that NBSL has a systematic effect on the spatial distribution of VF sensitivity.

Improving our understanding, and detection, of glaucomatous damage: An approach based upon optical coherence tomography (OCT)

Although ophthalmologists are becoming increasingly reliant upon optical coherence tomography (OCT), clinicians who care for glaucoma patients are not taking full advantage of the potential of this powerful technology. First, we ask, how would one describe the nature of glaucomatous damage if only OCT scans were available? In particular, a schematic model of glaucomatous damage is developed in section 2, and the nature of glaucomatous damage seen on OCT scans described in the context of this model in section 3. In particular, we illustrate that local thinning of the circumpapillary retinal nerve fiber layer (cpRNFL) around the optic disc can vary in location, depth, and/or width, as well as homogeneity of damage. Second, we seek to better understand the relationship between the thinning of the cpRNFL and the various patterns of sensitivity loss seen on visual fields obtained with standard automated perimetry. In sections 4 and 5, we illustrate why one should expect a wide range of visual field patterns, and iilustrate why they should not be placed into discrete categories. Finally, section 6 describes how the clinician can take better advantage of the information in OCT scans. The approach is summarized in a single-page report, which can be generated from a single wide-field scan. The superiority of this approach, as opposed to the typical reliance on summary metrics, is described.

Positional and Curvature Difference of Lamina Cribrosa According to the Baseline Intraocular Pressure in Primary Open-Angle Glaucoma: A Swept-Source Optical Coherence Tomography (SS-OCT) Study

Purpose

To investigate the variation of lamina cribrosa (LC) structure based on the baseline intraocular pressure (IOP) in eyes with primary open-angle glaucoma (POAG) and healthy individuals using swept-source optical coherence tomography.

Methods

A total of 108 eyes with POAG and 61 healthy eyes were recruited. Based on the baseline IOP, the POAG eyes were divided into higher-baseline IOP (HTG; baseline IOP > 21 mmHg, n = 38 eyes) and lower-baseline IOP (NTG; baseline IOP ≤ 21 mmHg, n = 70 eyes). The anterior laminar insertion depth (ALID), mean LC depth (mLCD), and the LC curvature index (mLCD–ALID) were measured, and compared among the three groups. The regional variation of LC structure was evaluated by vertical-horizontal ALID difference.

Results

The mLCD and LC curvature index were greatest in HTG eyes (520.3 ± 123.0 and 80.9 ± 30.7 μm), followed by NTG (463.2 ± 110.5 and 64.5 ± 30.7 μm) and healthy eyes (382.9 ± 107.6 and 47.6 ± 25.7 μm, all P < 0.001). However, there were no significant difference in ALID between HTG and NTG eyes. The vertical-horizontal ALID difference was larger in NTG eyes (72.8 ± 56.2 μm) than in HTG (32.7 ± 61.4 μm, P = 0.004) and healthy eyes (25.5 ± 34.8 μm, P < 0.001).

Conclusions

Lamina cribrosa position and curvature differed in POAG eyes with low and high IOP. This would support the theory that IOP induced biomechanical effects on the optic play a role on glaucoma.