Anatomic vs. acquired image frame discordance in spectral domain optical coherence tomography minimum rim measurements

OCT Optic Nerve Head Morphology in Myopia IV: Neural Canal Scleral Flange Remodeling in Highly Myopic Eyes

PURPOSE

To compare the prevalence, location and magnitude of optic nerve head (ONH) OCT-detected, exposed neural canal (ENC), externally oblique choroidal border tissue (EOCBT) and exposed scleral flange (ESF) regions in 122 highly myopic (Hi-Myo) versus 362 nonhighly myopic healthy (Non-Hi-Myo-Healthy) eyes.

DESIGN

Cross-sectional study.

METHODS

After OCT radial B-scan, ONH imaging, Bruch's membrane opening (BMO), the anterior scleral canal opening (ASCO), and the scleral flange opening (SFO) were manually segmented in each B-scan and projected to BMO reference plane. The direction and magnitude of BMO/ASCO offset and BMO/SFO offset as well as the location and magnitude of ENC, EOCBT and ESF regions, perineural canal (pNC) retinal nerve fiber layer thickness (RNFLT) and pNC choroidal thickness (CT) were calculated within 30° sectors relative to the Foveal-BMO (FoBMO) axis. Hi-ESF eyes were defined to be those with an ESF region ≥100 µms in at least 1 sector.

RESULTS

Hi-Myo eyes more frequently demonstrated Hi-ESF regions (87/122) than Non-Hi-myo-Healthy eyes (73/362) and contained significantly larger ENC, EOCBT, and ESF regions (P < .001) which were greatest in magnitude and prevalence within the inferior-temporal FoBMO sectors where Hi-Myo pNC-RNFLT and pNCCT were thinnest. BMO/ASCO offset and the BMO/SFO offset were both significantly increased (P < .001) in the Hi-Myo eyes, with the latter demonstrating a greater increase.

CONCLUSIONS

ENC region tissue remodeling that includes the scleral flange is enhanced in Hi-Myo compared to Non-Hi-Myo-Healthy eyes. Longitudinal studies are necessary to determine whether the presence of an ENC region influences ONH susceptibility to aging and/or glaucoma.

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.

Optical Coherence Tomographic Optic Nerve Head Morphology in Myopia III: The Exposed Neural Canal Region in Healthy Eyes-Implications for High Myopia

PURPOSE

To determine the prevalence and magnitude of optical coherence tomography (OCT) exposed neural canal (ENC), externally oblique choroidal border tissue (EOCBT), and exposed scleral flange (ESF) regions in 362 non-highly myopic (spherical equivalent -6.00 to 5.75 diopters) eyes of 362 healthy subjects.

DESIGN

Cross-sectional study.

METHODS

After OCT optic nerve head (ONH) imaging, Bruch membrane opening (BMO), the anterior scleral canal opening (ASCO), and the scleral flange opening (SFO) were manually segmented. BMO, ASCO, and SFO points were projected to the BMO reference plane. The direction and magnitude of BMO/ASCO offset as well as the magnitude of ENC, EOCBT, and ESF was calculated within 30° sectors relative to the foveal-BMO axis. Hi-ESF eyes demonstrated an ESF ≥100 µm in at least 1 sector. Sectoral peri-neural canal choroidal thickness (pNC-CT) was measured and correlations between the magnitude of sectoral ESF and proportional pNC-CT were assessed.

RESULTS

Seventy-three Hi-ESF (20.2%) and 289 non-Hi-ESF eyes (79.8%) were identified. BMO/ASCO offset as well as ENC, EOCBT, and ESF prevalence and magnitude were greatest inferior temporally where the pNC-CT was thinnest. Among Hi-ESF eyes, the magnitude of each ENC region correlated with the BMO/ASCO offset magnitude, and the sectors with the longest ESF correlated with the sectors with proportionally thinnest pNC-CT.

CONCLUSIONS

ONH BMO/ASCO offset, either as a cause or result of ONH neural canal remodeling, corresponds with the sectoral location of maximum ESF and minimum pNC-CT in non-highly myopic eyes. Longitudinal studies to characterize the development and clinical implications of ENC Hi-ESF regions in non-highly myopic and highly myopic eyes are indicated.

Increase in Bruch's membrane opening minimum rim width with age in healthy children: the Hong Kong Children Eye Study

BACKGROUND/AIMS

To identify normative values and determinants for Bruch's membrane opening (BMO) and the minimum rim width of BMO (BMO-MRW) among healthy children.

METHODS

A population-based cross-sectional study from the Hong Kong Children Eye Study, recruiting 1, 226 children aged 6-8 years. Spherical refractive error, axial length (AL), body mass index and intraocular pressure (IOP) were measured. The optic nerve head and the peripapillary retinal nerve fibre layer (p-RNFL) were imaged through spectral domain-optical coherence tomography, using 24 equally spaced radial B-scans. Global and sectoral BMO-MRW values, BMO area and fovea-to-BMO (FoBMO) angle were calculated. Multiple regression analysis was performed to define the determinants of BMO area and BMO-MRW in relation to demographic and ocular parameters.

RESULTS

The mean values for global BMO-MRW, BMO area and FoBMO angle among children were 345.76±54.08 µm, 2.34±0.49 mm2 and -5.45±4.36°, respectively. Global and sectoral values for BMO-MRW correlated with p-RNFL thickness (r=0.11-0.35, p<0.001). After adjusting for demographic and ocular parameters, global BMO-MRW increased with age (β=6.4, p<0.001) and greater global p-RNFL thickness (β=1.41, p<0.001), but decreased with larger BMO area (β=-47.46, p<0.001) and higher IOP (β=-1.73, p<0.001). Global BMO-MRW did not associate with AL, whereas both BMO area and FoBMO angle associated with AL (β=0.04, p=0.02 and β=0.31, p=0.03, respectively), but not with age.

CONCLUSION

We observed that BMO-MRW increases with age among children. Our results provide normative values and the determinants of BMO parameters among Chinese children.

OCT Optic Nerve Head Morphology in Myopia II: Peri-Neural Canal Scleral Bowing and Choroidal Thickness in High Myopia-An American Ophthalmological Society Thesis

PURPOSE

To use optical coherence tomography (OCT) to characterize optic nerve head (ONH) peri-neural canal (pNC) scleral bowing (pNC-SB) and pNC choroidal thickness (pNC-CT) in 69 highly myopic and 138 healthy, age-matched, control eyes.

DESIGN

Cross-sectional, case control study.

METHODS

Within ONH radial B-scans, Bruch membrane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and pNC scleral surface were segmented. BMO and ASCO planes and centroids were determined. pNC-SB was characterized within 30° foveal-BMO (FoBMO) sectors by 2 parameters: pNC-SB-scleral slope (pNC-SB-SS), measured within 3 pNC segments (0-300, 300-700, and 700-1000 μm from the ASCO centroid); and pNC-SB-ASCO depth relative to a pNC scleral reference plane (pNC-SB-ASCOD). pNC-CT was calculated as the minimum distance between the scleral surface and BM at 3 pNC locations (300, 700, and 1100 μm from the ASCO).

RESULTS

pNC-SB increased and pNC-CT decreased with axial length (P < .0133; P < .0001) and age (P < .0211; P < .0004) among all study eyes. pNC-SB was increased (P < .001) and pNC-CT was decreased (P < .0279) in the highly myopic compared to control eyes, and these differences were greatest in the inferior quadrant sectors (P < .0002). Sectoral pNC-SB was not related to sectoral pNC-CT in control eyes, but was inversely related to sectoral pNC-CT (P < .0001) in the highly myopic eyes.

CONCLUSIONS

Our data suggest that pNC-SB is increased and pNC-CT is decreased in highly myopic eyes and that these phenomena are greatest in the inferior sectors. They support the hypothesis that sectors of maximum pNC-SB may predict sectors of greatest susceptibility to aging and glaucoma in future longitudinal studies of highly myopic eyes. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Structural and vascular changes in glaucoma with single-hemifield defect: predictors of opposite hemifield visual field progression

PURPOSE

To investigate longitudinal changes in optic nerve head (ONH) superficial vessel density (VD), macular VD, circumpapillary retinal nerve fiber layer (RNFL) thickness, and macular ganglion cell-inner plexiform layer (GCIPL) thickness, and their associations with future VF defects in unaffected hemifields of primary open angle glaucoma (POAG) eyes with baseline VF defect confined to a single hemifield.

METHODS

This retrospective observational study included 61 POAG eyes with VF defect confined to a single hemifield monitored over a mean follow-up time of 2.7 years. Development of VF defect in opposite hemifield was defined based the Early Manifest Glaucoma Trail criteria. Each eye was classified into either "conversion" or "no conversion" groups according to development of VF defect in the unaffected hemifield. The rates of longitudinal changes in VD and structure parameters in each hemiretina were compared between the two groups. A Cox proportional hazard model was used to identify potential risk factors for VF conversion in the unaffected hemifield.

RESULTS

Among 61 eyes, 17 eyes (27.9%) were classified as "conversion" and 44 eyes (72.1%) were classified as "non-conversion" groups. The conversion group exhibited significantly greater rates of both VD and structural changes in both hemiretinas. In Cox proportional hazard model, greater rate of change in GCIPL thickness, ONH superficial VD, and macular VD of both hemiretinas and greater rate of change in RNFL thickness of the unaffected hemiretina were identified as risk factors for VF conversion in the unaffected hemifield.

CONCLUSIONS

Monitoring progressive changes in VD and structural parameters effectively predict future VF defect in the opposite hemifields of POAG eyes with single-hemifield defects.

Optic Nerve Head Myelin-Related Protein, GFAP, and Iba1 Alterations in Non-Human Primates With Early to Moderate Experimental Glaucoma

Purpose

The purpose of this study was to test if optic nerve head (ONH) myelin basic protein (MBP), 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase), glial fibrillary acidic protein (GFAP), and ionized calcium binding adaptor molecule 1 (Iba1) proteins are altered in non-human primate (NHP) early/moderate experimental glaucoma (EG).

Methods

Following paraformaldehyde perfusion, control and EG eye ONH tissues from four NHPs were paraffin embedded and serially (5 µm) vertically sectioned. Anti-MBP, CNPase, GFAP, Iba1, and nuclear dye-stained sections were imaged using sub-saturating light intensities. Whole-section images were segmented creating anatomically consistent laminar (L) and retrolaminar (RL) regions/sub-regions. EG versus control eye intensity/pixel-cluster density data within L and two RL regions (RL1 [1-250 µm]/RL2 [251-500 µm] from L) were compared using random effects models within the statistical program “R.”

Results

EG eye retinal nerve fiber loss ranged from 0% to 20%. EG eyes’ MBP and CNPase intensity were decreased within the RL1 (MBP = 31.4%, P < 0.001; CNPase =62.3%, P < 0.001) and RL2 (MBP = 19.6%, P < 0.001; CNPase = 56.1%, P = 0.0004) regions. EG eye GFAP intensity was decreased in the L (41.6%, P < 0.001) and RL regions (26.7% for RL1, and 28.4% for RL2, both P < 0.001). Iba1+ and NucBlue pixel-cluster density were increased in the laminar (28.2%, P = 0.03 and 16.6%, P = 0.008) and both RL regions (RL1 = 37.3%, P = 0.01 and 23.7%, P = 0.0002; RL2 = 53.7%, P = 0.002 and 33.2%, P < 0.001).

Conclusions

Retrolaminar myelin disruption occurs early in NHP EG and may be accompanied by laminar and retrolaminar decreases in astrocyte process labeling and increases in microglial/ macrophage density. The mechanistic and therapeutic implications of these findings warrant further study.

Comparison of Diagnostic Ability Between Wide-Field Swept-Source Optical Coherence Tomography Imaging Maps and Heidelberg Retina Tomograph 3 Optic Nerve Head Assessment to Discriminate Glaucomatous and Non-glaucomatous Eyes

Background

In this study, we aimed to determine the diagnostic performance of optic nerve head (ONH), macular, and circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements of wide-field maps (12 × 9 mm) using swept-source optical coherence tomography (SS-OCT) compared to measurements of the ONH and RNFL parameters measured by Heidelberg Retina Tomograph (HRT3).

Methodology

This case-control study included 39 eyes of 39 glaucoma patients and 36 eyes of 36 normal subjects (control group). All participants underwent standard automated perimetry (SAP) as well as structural measurements by SS-OCT (DRI-OCT, Triton; Topcon Inc., Tokyo, Japan) and HRT3 (Heidelberg Engineering, Heidelberg, Germany). The abilities of the continuous parameters to discriminate between glaucoma and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). To assess the glaucoma diagnostic abilities of each of the categorical variables, sensitivity, specificity, positive predictive value, and negative predictive value were tested.

Results

The highest sensitivities were achieved by the DRI-OCT categorical parameters of Superpixel-200 map and cpRNFL (12 sectors) thickness analysis. The best performing HRT3 continuous parameter was rim volume (AUC = 0.829, 95% confidence interval (CI) = 0.735-0.922), and the best continuous parameter for DRI-OCT wide-field was vertical cdr (AUC = 0.883, 95% CI = 0.805-0.951), followed by total cpRNFL thickness (AUC = 0.862, 95% CI = 0.774-0.951). AUCs for disc area, rim area, linear cdr, and RNFL thickness were not significantly different between the two technologies. Using either the most or the least specific criteria, SuperPixel-200 map always showed the highest sensitivity among the categorical parameters of both technologies (82.1% and 89.7%, respectively). The highest sensitivity among HRT3 classification parameters was shown by MRA and GPS classification algorithms.

Conclusions

Both wide-field DRI-OCT maps and HRT3 showed good diagnostic performance in discriminating glaucoma. Although DRI-OCT thickness values and normative diagnostic classification showed the best performance, more studies are required to determine the clinical role of wide-field DRI-OCT scan in glaucoma diagnosis.

Widefield OCT Imaging for Quantifying Inner Retinal Thickness in the Nonhuman Primate

Purpose

To determine the agreement and repeatability of inner retinal thickness measures from widefield imaging compared to standard scans in healthy nonhuman primates.

Methods

Optical coherence tomography (OCT) scans were acquired from 30 healthy rhesus monkeys, with 11 animals scanned at multiple visits. The scan protocol included 20° × 20° raster scans centered on the macula and optic nerve head (ONH), a 12° diameter circular scan centered on the ONH, and a 55 × 45° widefield raster scan. Each scan was segmented using custom neural network–based algorithms. Bland–Altman analysis were used for comparing average circumpapillary retinal nerve fiber layer (RNFL) thickness and ganglion cell inner plexiform layer (GCIPL) thickness for a 16° diameter region. Comparisons were also made for similar 1° × 1° superpixels from the raster scans.

Results

Average circumpapillary RNFL thickness from the circular scan was 114.2 ± 5.8 µm, and 113.2 ± 7.3 µm for an interpolated scan path from widefield imaging (bias = −1.03 µm, 95% limits of agreement [LOA] −8.6 to 6.5 µm). GCIPL thickness from standard raster scans was 72.7 ± 4.3 µm, and 73.7 ± 3.7 µm from widefield images (bias = 1.0 µm, 95% LOA −2.4 to 4.4 µm). Repeatability for both RNFL and GCIPL standard analysis was less than 5.2 µm. For 1° × 1° superpixels, the 95% limits of agreement were between −13.9 µm and 13.7 µm for RNFL thickness and −2.5 µm and 2.5 µm for GCIPL thickness.

Conclusions

Inner retinal thickness measures from widefield imaging have good repeatability and are comparable to those measured using standard scans.

Translational Relevance

Monitoring retinal ganglion cell loss in the non-human primate experimental glaucoma model could be enhanced using widefield imaging.

Uncovering of intraspecies macular heterogeneity in cynomolgus monkeys using hybrid machine learning optical coherence tomography image segmentation

The fovea is a depression in the center of the macula and is the site of the highest visual acuity. Optical coherence tomography (OCT) has contributed considerably in elucidating the pathologic changes in the fovea and is now being considered as an accompanying imaging method in drug development, such as antivascular endothelial growth factor and its safety profiling. Because animal numbers are limited in preclinical studies and automatized image evaluation tools have not yet been routinely employed, essential reference data describing the morphologic variations in macular thickness in laboratory cynomolgus monkeys are sparse to nonexistent. A hybrid machine learning algorithm was applied for automated OCT image processing and measurements of central retina thickness and surface area values. Morphological variations and the effects of sex and geographical origin were determined. Based on our findings, the fovea parameters are specific to the geographic origin. Despite morphological similarities among cynomolgus monkeys, considerable variations in the foveolar contour, even within the same species but from different geographic origins, were found. The results of the reference database show that not only the entire retinal thickness, but also the macular subfields, should be considered when designing preclinical studies and in the interpretation of foveal data.

Visual Field Cluster Map Corresponding to Bruch Membrane Opening-minimum Rim Area Sectors in Open-angle Glaucoma

PRéCIS:: We generated a new visual field (VF) cluster map corresponding to Bruch membrane opening-minimum rim area (BMO-MRA) sectors, which described in detail the structure-function relationships between the optic nerve head and VF in patients with open-angle glaucoma.

PURPOSE

The purpose of this study was to investigate the structure-function relationship between BMO-MRA and VF in patients with open-angle glaucoma.

MATERIALS AND METHODS

We retrospectively reviewed 67 eyes of 50 patients with open-angle glaucoma who underwent spectral-domain optical coherence tomography for BMO-MRA and the Humphrey VF test. BMO-MRA of the glaucomatous optic nerve head was divided into 12 sectors. The correlation between BMO-MRA sectors and the VF points was analyzed to generate a new VF cluster map.

RESULTS

Forty-three of the 52 VF points showed a significant correlation with at least 1 BMO-MRA sector. The VF cluster map was generated using the BMO-MRA sectors and each VF point that showed the most correlation. The superior hemifield correlated with 5, 6, 7, and 8 o'clock positions (ρ=0.312 to 0.710), whereas the inferior hemifield correlated with 10, 11, 12, and 2 o'clock positions (ρ=0.241 to 0.483). The VF cluster maps of superior and inferior hemifields showed different configurations of VF clusters and topographical relationships with the glaucomatous optic nerve head.

CONCLUSION

The newly generated VF cluster map corresponding to BMO-MRA sectors showed a significant structure-function relationship and could be useful in the diagnosis and evaluation of glaucoma.

Peripapillary Scleral Bowing Increases with Age and Is Inversely Associated with Peripapillary Choroidal Thickness in Healthy Eyes

PURPOSE

To use optical coherence tomography (OCT) to 3-dimensionally characterize the optic nerve head (ONH) in peripapillary scleral bowing in non-highly myopic healthy eyes.

DESIGN

Cross-sectional, multicenter study.

METHODS

A total of 362 non-highly myopic (+6 diopters [D] > spherical equivalent > -6D) eyes of 362 healthy subjects from 20-90 years old underwent OCT ONH radial B-scan imaging. Bruch's membrane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and the peripapillary scleral surface were segmented. BMO and ASCO planes were fit, and their centroids, major axes, ovality, areas and offsets were determined. Peripapillary scleral bowing was characterized by 2 parameters: peripapillary scleral slope (ppSS) of 3 anterior peripapillary scleral segments (0-300, 300-700, and 700-1,000 μm from the ASCO centroid); and ASCO depth relative to a peripapillary scleral reference plane (ASCOD-ppScleral). Peripapillary choroidal thickness (ppCT) was calculated relative to the ASCO as the minimum distance between the anterior scleral surface and BM.

RESULTS

Both ppSS and ASCOD-ppScleral ranged from slightly inward through profoundly outward in direction. Both parameters increased with age and were independently associated with decreased ppCT.

CONCLUSIONS

In non-highly myopic healthy eyes, outward peripapillary scleral bowing achieved substantial levels, was markedly increased with age, and was independently associated with decreased peripapillary choroidal thickness. These findings provide a normative foundation for characterizing this anatomy in cases of high myopia and glaucoma and in eyes with optic disc tilt, torsion, and peripapillary atrophy.

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.

Optical Coherence Tomography Structural Abnormality Detection in Glaucoma Using Topographically Correspondent Rim and Retinal Nerve Fiber Layer Criteria

PURPOSE

This study evaluated the ability of topographically correspondent (TC) minimum rim width (MRW) and peripapillary retinal nerve fiber layer thickness (pRNFLT) criteria to detect optical coherence tomography (OCT) structural abnormality in glaucoma (GL) and glaucoma suspect (GLS) eyes.

DESIGN

Retrospective cross-sectional study.

METHODS

A total of 196 GL eyes, 150 GLS eyes, and 303 heathy eyes underwent pRNFL and 24 radial optic nerve head OCT imaging and manual correction of the internal limiting membrane, Bruch's membrane opening (BMO), and outer pRNFL segmentations. MRW and pRNFLT were quantified in 6 Garway-Heath or 12 30-degree (clock-hour) sectors. OCT abnormality for each parameter was defined to be less than the 5th percentile of the healthy eye distribution. OCT abnormality for individual eyes was defined using global, sectoral, and combined parameter criteria that achieved ≥95% specificity in the healthy eyes. TC combination criteria required the sectoral location of MRW and pRNFLT abnormality to be topographically aligned and included comMR (a previously reported TC combination consisting of MRW and pRNFLT parameter: [MRW + pRNFLT × (average MRW healthy eyes/average pRNFLT healthy eyes) MRW].

RESULTS

TC sectoral criteria (1 Garway-Heath MRW + corresponding Garway-Heath RNFLT), (one 30-degree MRW + any 1 corresponding or adjacent 30-degree pRNFLT), 30-degree and Garway-Heath comMR-TI and global comMR were the best performing criteria, demonstrating (96%-99% specificity), 86%-91% sensitivity for GL, 80%-84% sensitivity for early GL (MD ≥ -4.0 dB) and 93%-96% sensitivity for moderate-to-advanced GL (MD < -4.0 dB).

CONCLUSIONS

Clinically intuitive TC MRW and pRNFLT combination criteria identified the sectoral location of OCT abnormality in GL eyes with high diagnostic precision.

Interocular Asymmetry of Minimum Rim Width and Retinal Nerve Fiber Layer Thickness in Healthy Brazilian Individuals

PURPOSE

To determine interocular differences in Bruch's membrane opening minimum rim width (BMO-MRW) and retinal nerve fiber layer thickness (RNFLT) in healthy Brazilian individuals.

MATERIALS AND METHODS

Both eyes of 220 healthy individuals were included in this observational, cross-sectional study. All individuals had normal clinical examination and visual fields. Global and sectorial interocular BMO-MRW and RNFLT differences, acquired and regionalized relative to the fovea to BMO center (FoBMO) axis, were calculated. The effect of age, axial length, and BMO area asymmetry on the parameters' asymmetry was evaluated.

RESULTS

The 95th limits for interocular BMO-MRW and RNFLT global differences were 49 and 9 μm, respectively. BMO-MRW asymmetry was negatively correlated (β=-33.87 μm/mm, R=0.06, P<0.001), whereas RNFLT asymmetry was positively correlated (β= 6.13 μm/mm, R=0.09, P<0.001) with BMO area asymmetry. Neither BMO-MRW nor RNFLT asymmetries were correlated with axial length asymmetry (β=-16.90 μm/mm, R=0.00, P=0.15; β=-1.18 μm/mm, R=0.00, P=0.52, respectively). Similarly, BMO-MRW and RNFLT asymmetries were not correlated with age (β=0.17 μm/y, R=0.01, P=0.22; β=0.0 μm/y, R=0.00, P=0.19, respectively).

CONCLUSIONS

Our results suggest that global BMO-MRW and RNFLT interocular differences exceeding 49 and 9 μm, respectively, may indicate statistically abnormal asymmetry, which may suggest early structural damage. Asymmetry in BMO area should be accounted for when considering interocular asymmetry in BMO-MRW and RNFLT.

The Fovea-BMO Axis Angle and Macular Thickness Vertical Asymmetry Across The Temporal Raphe

PURPOSE

To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) axis angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects.

DESIGN

Cross-sectional diagnostic study at a tertiary academic center.

METHODS

One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO angle were investigated.

RESULTS

No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P<0.001). The second row of temporal superpixels from the horizontal meridian (P=0.349) or central superpixels (P=0.292) did not show this tendency.

CONCLUSIONS

Vertical GCIPL symmetry across the horizontal meridian is influenced by the FoBMO angle. SD-OCT algorithms using vertical asymmetry as a diagnostic index should be adjusted for the FoBMO angle.

Impact of Head Tilt on Optical Coherence Tomography Image Orientation

PURPOSE

Head tilt can have an impact on the orientation of posterior pole images. We conducted this study to determine the effect of head tilt on image orientation measured by the fovea-Bruch's membrane opening (FoBMO) angle with optical coherence tomography (OCT) imaging.

METHODS

The study included 56 healthy subjects with mean (range) age of 33 (18 to 61) years. The dominant eye was first determined. To measure head tilt, a smartphone with a built-in gyroscope was affixed to the subject's head with adjustable straps. OCT imaging was performed in both eyes (in randomized order) at 0, 5, and 10 degrees of head tilt in the direction of the imaged eye (ipsilateral head tilt), and then in the opposite direction (contralateral head tilt). For each image, the device software determined Bruch's membrane opening center and the foveal pit from which the FoBMO angle was derived.

RESULTS

Thirty-eight (68%) subjects were right eye dominant and 18 (32%) were left eye dominant. Each 1 degree head tilt resulted in a mean change of 0.76 degree in the FoBMO angle (P<0.01), with no significant difference in effect between the 2 eyes (P=0.72). The magnitude of the effect increased from 5 to 10 degrees, and was similar for both ipsilateral and contralateral head tilt. Ocular dominance did not modulate the effect of head tilt (P=0.42).

CONCLUSIONS

Head tilt significantly affects OCT image orientation as measured by the FoBMO angle, presumably because cyclotorsion is not fully compensatory. The magnitude and direction of the effect does not depend on the dominant eye.

Factors Influencing Optical Coherence Tomography Peripapillary Choroidal Thickness: A Multicenter Study

Purpose

To quantify peripapillary choroidal thickness (PCT) and the factors that influence it in healthy participants who represent the racial and ethnic composition of the U.S. population.

Methods

A total of 362 healthy participants underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head with a 24 radial B-scan pattern aligned to the fovea to Bruch's membrane opening axis. Bruch's membrane, anterior scleral canal opening (ASCO), and the anterior scleral surface were manually segmented. PCT was measured at 100, 300, 500, 700, 900, and 1100 μm from the ASCO globally and within 12 clock-hour sectors. The effects of age, axial length, intraocular pressure, ethnicity, sex, sector, and ASCO area on PCT were assessed by ANOVA and univariable and multivariable regressions.

Results

Globally, PCT was thicker further from the ASCO border and thinner with older age, longer axial length, larger ASCO area, European descent, and female sex. Among these effectors, age and axial length explained the greatest proportion of variance. The rate of age-related decline increased further from the ASCO border. Sectorally, the inferior-temporal sectors were thinnest (10.7%-20.0% thinner than the thickest sector) and demonstrated a higher rate of age-related loss (from 15.6% to 20.7% faster) at each ASCO distance.

Conclusions

In healthy eyes, PCT was thinnest in the inferior temporal sectors and thinner PCT was associated with older age, European descent, longer axial length, larger ASCO area, and female sex. Among these associations, age had the strongest influence, and its effect was greatest within the inferior temporal sectors.

Glaucoma Specialist Detection of Optical Coherence Tomography Suspicious Rim Tissue in Glaucoma and Glaucoma Suspect Eyes

PURPOSE

To assess glaucoma specialists' detection of optic nerve head (ONH) rim tissue that is thin by optical coherence tomography (OCT) criteria.

DESIGN

Reliability analysis.

METHODS

Five clinicians marked the disc margin (DM) and rim margin (RM) on stereophotographs of 151 glaucoma or glaucoma suspect eyes obtained within 3 months of OCT imaging. The photo and OCT infrared image for each eye were co-localized and regionalized into 12 sectors relative to the axis between the Bruch membrane opening (BMO) centroid and the fovea. For each clinician, the distance from BMO centroid to their DM (DM radius) and RM (RM radius) was used to generate sectoral rim width (RW) (DM radius-RM radius) and cup-to-disc ratio (CDR) (RM radius/DM radius) estimates. OCT minimum rim width (MRW) was determined by sector. Among all eyes, for each OCT MRW suspicious sector (<5% of OCT normative database), we determined each clinician's detection (clinician CDR ≥ 0.7).

RESULTS

Clinicians most commonly failed to detect OCT suspicious rim tissue in the nasal sectors. Among 502 sectors with suspicious OCT MRW, all 5 clinicians rated CDR ≥ 0.7 in only 29.5% and all 5 clinicians rated CDR < 0.7 in 21%. OCT suspicious rim thickness was most common (32% of eyes) in the nasal and inferior sectors. MRW vs clinician RW discordance was greatest nasally, while BMO vs clinician DM discordance was greatest temporally.

CONCLUSIONS

Clinicians most commonly failed to detect OCT suspicious rim thickness nasally where suspicious rim tissues were also most common.

Factors Influencing Central Lamina Cribrosa Depth: A Multicenter Study

Purpose

To quantify the influence of ocular and demographic factors on central laminar depth (LD) in healthy participants.

Methods

A total of 362 normal subjects underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head (ONH) with a 24 radial B-scan pattern aligned to the fovea–to–Bruch's membrane opening (BMO) axis. BMO, anterior lamina, anterior scleral canal opening (ASCO), Bruch's membrane (BM), and the peripapillary scleral surface were manually segmented. The extent of laminar segmentation was quantified within 72 ASCO subsectors. Central LD was quantified relative to four reference planes: BMO, ASCO, BM, and scleral. The effects of age, sex, ethnicity, IOP, BMO area, ASCO area, and axial length on LD were assessed.

Results

Laminar visibility was most consistent within the central ASCO (median 89%, range, 69%–95%). LD_BMO and LD_BM were significantly shallower in eyes with greater age, BMO area, and axial length and in females. LD_ASCO was shallower in eyes with greater ASCO area and axial length and in European and Hispanic descent compared to African descent eyes. LD_Sclera behaved similarly, but was not associated with axial length. BMO and ASCO area were not different between African descent and European descent eyes.

Conclusions

Central LD was deeper in African descent eyes and influenced least by age, axial length, and sex, but more by ASCO area, when measured relative to the ASCO and sclera. However, the magnitude of these effects for all four reference planes was small, and their clinical importance in the detection of glaucoma and its progression remains to be determined.

Bruch's membrane opening minimum rim width and retinal nerve fiber layer thickness in a Brazilian population of healthy subjects

Objective

To determine Bruch’s membrane opening (BMO) minimum rim width (MRW) and peripapillary retinal nerve fiber layer thickness (RNFLT) measurements, acquired with optical coherence tomography (OCT) in healthy Brazilian individuals self-reported as African Descent (AD), European Descent (ED) and Mixed Descent (MD).

Methods

260 healthy individuals (78 AD, 103 ED and 79 MD) were included in this cross-sectional study conducted at the Clinics Hospital of the University of Campinas. We obtained optic nerve head (24 radial B scans) and peripapillary retinal nerve fiber layer (3.5-mm circle scan) images in one randomly selected eye of each subject.

Results

After adjustment for BMO area and age, there were no significant differences in mean global MRW (P = 0.63) or RNFLT (P = 0.07) among the three groups. Regionally, there were no significant differences in either MRW or RNFLT in most sectors, except in the superonasal sector, in which both MRW and RNFLT were thinner among ED (P = 0.04, P<0.001, respectively). RNFLT was also thinner in ED in the inferonasal sector (P = 0.009). In all races, global MRW decreased and global RNFLT increased with BMO area. AD subjects had higher rates of global RNFLT decay with age (-0.32 μm/year) compared to ED and MD subjects (-0.10 μm/year and -0.08 μm/year, respectively; P = 0.01 and P = 0.02, respectively).

Conclusions and relevance

While we found no significant differences in global MRW and RNFLT among the three races, age-related thinning of the RNFLT was significantly higher in the AD subgroup, which warrants further study.

Effects of the relative positioning between the disc-fovea angle and localized optic disc defects on the 10-2 visual field results in glaucoma

Purpose

To investigate the effects of the foveal position relative to the optic disc on the 10-2 visual field (VF) results of glaucoma patients with localized inferotemporal neuroretinal rim defects (ITD).

Design

Cross-sectional study.

Participants

Fifty-seven eyes of 35 open-angle glaucoma (OAG) patients were included and divided into two groups based upon the presence (18 eyes) or not (39 eyes) of ITD.

Methods

Three different parameters obtained from a spectral domain optic coherence tomography (sdOCT) [disc-fovea angle (DFA), fovea vertical deviation (FVD) from midline, and the angular difference between the ITD border and the DFA (DAD)] were tested for their relationship with four 10-2 VF sectors: superior hemifield, superior edge, nasal edge, and superonasal arcuate. These relationships were tested with regression analyses with linear mixed effects models and random intercepts.

Main Outcome Measures

Influences of DFA, FVD, and DAD on 10-2 VF sectors.

Results

Mean (±SD) values of DFA, FVD, and DAD were respectively: -5.05° ± 4.40°, -1346.6 um ± 1609.0 um, and 43.30° ± 17.33°. After adjustment for multiple comparisons, both FVD and DAD, but not DFA, were significantly associated with the severity of defects on the predefined VF sectors. Larger DAD values (third tertile: 54°-77°) showed higher coefficient estimate for the nasal edge sector sensitivities.

Conclusions

The vertical foveal location and its position relative to the ITD was associated with loss of sensitivity at 10-2 VF locations in the superior hemifield. This association was significant but weak and was not seen using other conventional parameters that describe foveal position relative to the optic disc on sdOCT.

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.

Glaucoma Specialist Optic Disc Margin, Rim Margin, and Rim Width Discordance in Glaucoma and Glaucoma Suspect Eyes

PURPOSE

To quantify the variability of 5 glaucoma specialists' optic disc margin (DM), rim margin (RM), and rim width (RW) estimates.

DESIGN

Inter-observer reliability analysis.

METHODS

Clinicians viewed stereo-photographs from 214 subjects with glaucoma or ocular hypertension and digitally marked the DM and RM. For each photograph, the centroid of each clinician's DM was calculated, and an averaged DM_centroid was determined. The axis between the DM_centroid and the fovea was used to establish 12 30-degree sectors. Measurements from the DM_centroid to each clinician's DM (DM_radius) and RM (RM_radius) were used to generate a RW (DM_radius-RM_radius) and cup-to-disc ratio (CDR) (RM_radius/DM_radius) by sector. Parameter means, standard deviations, and coefficient of variations (COVs) were calculated across all clinicians for each eye. Parameter means for each clinician, and intraclass correlation coefficients (ICC), were calculated across all eyes by sector.

RESULTS

Among all eyes, the median COV by sector ranged from 3% to 5% for DM_radius, 20% to 25% for RM_radius, and 26% to 30% for RW. Sectoral ICCs for CDR ranged from 0.566 to 0.668. Sectors suspicious for rim thinning by 1 clinician were frequently overlooked by others. Among 1724 sectors in which at least 1 clinician was suspicious for rim thinning (CDR ≥ 0.7), all 5 clinicians' CDRs were ≥ 0.7 in only 499 (29%), and 2 of the 5 clinicians failed to detect rim thinning (CDR < 0.7) in 442 (26%).

CONCLUSION

In this study, glaucoma specialist RM, DM, and RW discordance was frequent and substantial, even in sectors that were suspicious for rim thinning.

Longitudinal Changes of Optic Nerve Head and Peripapillary Structure during Childhood Myopia Progression on OCT: Boramae Myopia Cohort Study Report 1

PURPOSE

To delineate longitudinal changes in the optic nerve head (ONH) and peripapillary structure during myopia progression in childhood using spectral-domain (SD) OCT and to explore the factors associated with myopic ONH and peripapillary changes.

DESIGN

Prospective cohort study.

PARTICIPANTS

Twenty-three healthy children with myopia (46 eyes).

METHODS

The participants underwent fundus photography, SD OCT, and axial length (AXL) measurements every 6 months for 2 years. Based on the morphologic changes of the ONH and β-zone parapapillary atrophy (PPA), eyes were classified as group A (ONH unchanged without β-zone PPA; 11 eyes), group B (ONH changed without β-zone PPA at baseline; 10 eyes), group C (ONH changed with β-zone PPA at baseline; 15 eyes), and group D (ONH unchanged with β-zone PPA; 10 eyes). The configuration of the border tissue (BT) at the temporal margin of the ONH was assessed, and the ONH parameters, including Bruch's membrane opening distance (BMOD), border length (BL), and BT angle (BTA), were measured on horizontal SD OCT scans.

MAIN OUTCOME MEASURES

Changes in ONH parameters and associated factors.

RESULTS

Group B showed the greatest AXL increase per year (group B > group C > group A = group D; P < 0.001). During the follow-up periods, the BT configuration initially was changed from internally oblique to externally oblique (group B) and was stretched, resulting in optic disc ovality and γ-zone PPA development (group C). In group C, BL was increased significantly nasally and BTA was decreased significantly, whereas BMOD remained stable (P < 0.001, P < 0.001, and P = 0.100, respectively). In the multivariate analysis using the generalized linear mixed-effect model, the changes of BL and BTA were associated with axial elongation (P = 0.028 and P = 0.010, respectively).

CONCLUSIONS

Development of myopic optic disc and γ-zone PPA during myopia progression was delineated using SD OCT images. During the ONH and peripapillary changes, the BL was increased nasally and the BTA was decreased, whereas the BMOD remained relatively stable. The association of axial elongation with ONH and peripapillary tissue changes may facilitate understanding of the relationship between myopia and glaucoma.

3D Histomorphometric Reconstruction and Quantification of the Optic Nerve Head Connective Tissues

Accurately characterizing the 3D geometry of the optic nerve head neural and connective tissues has been the goal of a large and important body of scientific work. In the present report, we summarize our methods for the high-resolution, digital, 3D histomorphometric reconstruction of the optic nerve head tissues, including their visualization, parameterization, and quantification. In addition, we present our methods for between-eye comparisons of this anatomy, and their use to determine animal-specific and experiment-wide experimental glaucoma versus Control eye differences in the unilateral, monkey experimental glaucoma model. Finally, we demonstrate its application to finite element modeling, 3D optic nerve head reconstruction of other species, and 3D optic nerve head reconstructions using other imaging modalities.

Reproducibility of Bruch Membrane Opening-Minimum Rim Width Measurements With Spectral Domain Optical Coherence Tomography

PURPOSE

To evaluate the reproducibility of Bruch membrane opening-minimum rim width (BMO-MRW) measurements obtained with Spectralis optical coherence tomography (OCT) in normal and glaucoma subjects.

MATERIALS AND METHODS

In total, 123 eyes from 123 subjects (65 healthy, 58 glaucoma subjects) were included. BMO-MRW measurements were repeated 3 times during the same visit using Spectralis OCT. The BMO points and internal limiting membrane were identified with automated software and corrected manually when necessary. The intravisit repeatability, coefficient of variation (CV), and intraclass correlation coefficient were analyzed for each sector and global BMO-MRW. The Spearman rank correlation coefficient was used to estimate correlations between CV and multiple variables. Multiple linear regression analysis was used to identify significant associations.

RESULTS

The intravisit repeatability ranged from 2.97 μm (global) to 10.25 μm (inferotemporal sector) in healthy subjects and from 3.31 μm (global) to 12.09 μm (inferonasal sector) in glaucoma subjects. The CVs ranged from 1.17% (global) to 3.56% (inferotemporal sector) in healthy subjects and from 2.57% (global) to 6.46% (superotemporal and inferotemporal sector) in glaucoma subjects. Intraclass correlation coefficients ranged from 0.974 (superotemporal sector) to 0.997 (nasal sector) in normal subjects and from 0.988 (temporal sector) to 0.997 (global and nasal sector) in glaucoma subjects. Multiple regression analysis showed that the CV in global BMO-MRW measurements was inversely associated with global BMO-MRW and visual field mean deviation (P=0.001 and 0.002, respectively).

CONCLUSIONS

The Spectralis SD-OCT showed excellent reproducibility in BMO-MRW measurements in both normal and glaucoma subjects. The measurements variability was worse in more advanced glaucoma.

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.

Comparison of the Deep Optic Nerve Structures in Superior Segmental Optic Nerve Hypoplasia and Primary Open-Angle Glaucoma

PURPOSE

The purpose of this study was to characterize the microstructure of the deep optic nerve tissues in eyes with superior segmental optic nerve hypoplasia (SSOH) in comparison with that in primary open-angle glaucoma (POAG).

METHODS

Thirty-five eyes with SSOH, 37 eyes with POAG, and 54 healthy control eyes underwent enhanced depth imaging (EDI) volume scanning of the optic nerve using spectral-domain optical coherence tomography (SD-OCT). POAG patients were matched with SSOH patients in terms of the thickness of the neuroretinal rim and the retinal nerve fiber layer in the superior sector. The lamina cribrosa thickness (LCT) was determined in 3 equidistant planes, and anterior lamina cribrosa surface depth (LCD) was determined in 5 equidistant planes. The measurements were compared between groups, and the areas under the receiver operating characteristic curves (AUC) were obtained for each parameter.

RESULTS

Eyes with SSOH had larger LCT and smaller LCD than POAG eyes at all locations (all P<0.001). The largest LCT was observed at the superior midperiphery in the SSOH group, but at central locations in both the POAG and control groups. The best parameters for discriminating the SSOH from glaucoma and healthy eyes were the superior midperipheral LCT (AUC=0.973) and inferior and inferior midperipheral LCD (AUCs=0.906), respectively.

CONCLUSIONS

The LCT and LCD exhibited characteristic features in eyes with SSOH that were distinctive from those of POAG and healthy eyes. Investigation of the deep optic nerve structure using EDI SD-OCT may be beneficial for differentiating between SSOH and glaucoma, which may help to avoid both overtreatment and undertreatment.

The connective tissue phenotype of glaucomatous cupping in the monkey eye - Clinical and research implications

In a series of previous publications we have proposed a framework for conceptualizing the optic nerve head (ONH) as a biomechanical structure. That framework proposes important roles for intraocular pressure (IOP), IOP-related stress and strain, cerebrospinal fluid pressure (CSFp), systemic and ocular determinants of blood flow, inflammation, auto-immunity, genetics, and other non-IOP related risk factors in the physiology of ONH aging and the pathophysiology of glaucomatous damage to the ONH. The present report summarizes 20 years of technique development and study results pertinent to the characterization of ONH connective tissue deformation and remodeling in the unilateral monkey experimental glaucoma (EG) model. In it we propose that the defining pathophysiology of a glaucomatous optic neuropathy involves deformation, remodeling, and mechanical failure of the ONH connective tissues. We view this as an active process, driven by astrocyte, microglial, fibroblast and oligodendrocyte mechanobiology. These cells, and the connective tissue phenomena they propagate, have primary and secondary effects on retinal ganglion cell (RGC) axon, laminar beam and retrolaminar capillary homeostasis that may initially be "protective" but eventually lead to RGC axonal injury, repair and/or cell death. The primary goal of this report is to summarize our 3D histomorphometric and optical coherence tomography (OCT)-based evidence for the early onset and progression of ONH connective tissue deformation and remodeling in monkey EG. A second goal is to explain the importance of including ONH connective tissue processes in characterizing the phenotype of a glaucomatous optic neuropathy in all species. A third goal is to summarize our current efforts to move from ONH morphology to the cell biology of connective tissue remodeling and axonal insult early in the disease. A final goal is to facilitate the translation of our findings and ideas into neuroprotective interventions that target these ONH phenomena for therapeutic effect.

Atlas-based shape analysis and classification of retinal optical coherence tomography images using the functional shape (fshape) framework

We propose a novel approach for quantitative shape variability analysis in retinal optical coherence tomography images using the functional shape (fshape) framework. The fshape framework uses surface geometry together with functional measures, such as retinal layer thickness defined on the layer surface, for registration across anatomical shapes. This is used to generate a population mean template of the geometry-function measures from each individual. Shape variability across multiple retinas can be measured by the geometrical deformation and functional residual between the template and each of the observations. To demonstrate the clinical relevance and application of the framework, we generated atlases of the inner layer surface and layer thickness of the Retinal Nerve Fiber Layer (RNFL) of glaucomatous and normal subjects, visualizing detailed spatial pattern of RNFL loss in glaucoma. Additionally, a regularized linear discriminant analysis classifier was used to automatically classify glaucoma, glaucoma-suspect, and control cases based on RNFL fshape metrics.

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.

Optical coherence tomography platforms and parameters for glaucoma diagnosis and progression

PURPOSE OF REVIEW

Optical coherence tomography (OCT) aids in the diagnosis and long-term monitoring of various ocular diseases, including glaucoma. Initially, the retinal nerve fiber layer was the only OCT structural parameter used in glaucoma. Subsequent research has resulted in more retinal and optic nerve head parameters. In addition, OCT is being investigated for its ability to assess ocular hemodynamics. This review summarizes these spectral domain-optical coherence tomography (SDOCT) parameters in the context of glaucoma.

RECENT FINDINGS

Several new SDOCT retinal nerve fiber layer, optic nerve head, and macular parameters with good glaucoma diagnostic ability have been added to existing ones recently. The combination of SDOCT and Doppler or angiography has also resulted in hemodynamic parameters that may prove to be useful in the functional assessment in glaucoma.

SUMMARY

OCT technology is advancing not only as a tool for structural assessment, but also as a multimodality tool to assess both structure and function to enhance our understanding of glaucoma, and ultimately clinical decisions.

Optical coherence tomography of the preterm eye: from retinopathy of prematurity to brain development

Preterm infants with retinopathy of prematurity are at increased risk of poor neurodevelopmental outcomes. Because the neurosensory retina is an extension of the central nervous system, anatomic abnormalities in the anterior visual pathway often relate to system and central nervous system health. We describe optical coherence tomography as a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside. Optical coherence tomography has increased understanding of normal eye development and has identified several potential biomarkers of brain abnormalities and poorer neurodevelopment.

The morphological difference between glaucoma and other optic neuropathies

The clinical phenomenon of cupping has 2 principal pathophysiologic components in all optic neuropathies: prelaminar thinning and laminar deformation. We define prelaminar thinning to be the portion of cup enlargement that results from thinning of the prelaminar tissues due to physical compression and/or loss of retinal ganglion cell axons. We define laminar deformation or laminar cupping to be the portion of cup enlargement that results from permanent intraocular pressure (IOP)-induced deformation of the lamina cribrosa and peripapillary scleral connective tissues after damage and/or remodeling. We propose that the defining phenomenon of glaucomatous cupping is deformation and/or remodeling of the neural and connective tissues of the optic nerve head (ONH), which is governed by the distribution of IOP-related connective tissue stress and strain, regardless of the mechanism of insult or the level of IOP at which deformation and/or remodeling occurs. In other words, "glaucomatous cupping" is the term clinicians use to describe the clinical appearance and behavior the ONH assumes as its neural and connective tissues deform, remodel, or mechanically fail: 1) in a pattern and 2) by the several pathophysiologic processes governed by IOP-related connective tissue stress and strain. ONH biomechanics explains why a given ONH will demonstrate a certain form of "cupping" and at what level of IOP that might happen. Animal models are allowing us to tease apart the important components of cupping in IOP-related and non-IOP-related forms of optic neuropathy. A paradigm change in spectral domain optical coherence tomography ONH, retinal nerve fiber layer, and macular imaging should improve our ability to phenotype the ocular manifestations of many forms of damage to the visual system including glaucoma.

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

PURPOSE

To compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness, specificity, and glaucoma discriminating ability prior and following adjustment to the fovea-disc angle axis.

DESIGN

Cross-sectional observational study.

METHODS

Fovea-disc angle was measured in 282 healthy subjects (normative database), 46 nonglaucomatous myopic subjects, and 86 glaucomatous subjects. The fovea-disc angle was determined using the Cirrus PanoMap feature after registering the macular ocular fundus image to the peripapillary ocular fundus image. RNFL prediction limits, specificity, and glaucoma discrimination ability were determined before and after adjustment to fovea-disc angle axis.

RESULTS

The mean fovea-disc angles were 7.4 ± 4.1 degrees (normative database), 7.1 ± 4.3 degrees (myopic subjects), and 7.6 ± 4.2 degrees (glaucomatous subjects) (all P > .05). Standard and fovea-disc angle-adjusted RNFL thicknesses showed small significant differences in quadrants and larger differences in clock-hour sectors (all P < .05), without consistent patterns in the direction of the change. The specificity remained unchanged for all parameters in normative database subjects after adjustment to fovea-disc angle. The number of sectors with improved specificity and those with worsened specificity did not differ significantly in the first (8 vs 6), second (5 vs 8), and random (6 vs 7) normative database half (all P > .05). In myopic subjects, the specificity improved and worsened in 4 sectors in each case. The glaucoma discriminating ability significantly increased in 6 sectors and decreased in 5 others.

CONCLUSION

Correcting the RNFL profiles using the fovea-disc angle axis had no consistent effect on the thickness, specificity, and glaucoma diagnostic performance of RNFL parameters. This phenomenon may be specific to different OCT platforms.

Bruch's Membrane Opening Minimum Rim Width and Retinal Nerve Fiber Layer Thickness in a Normal White Population: A Multicenter Study

PURPOSE

Conventional optic disc margin-based neuroretinal rim measurements lack a solid anatomic and geometrical basis. An optical coherence tomography (OCT) index, Bruch's membrane opening minimum rim width (BMO-MRW), addresses these deficiencies and has higher diagnostic accuracy for glaucoma. We characterized BMO-MRW and peripapillary retinal nerve fiber layer thickness (RNFLT) in a normal population.

DESIGN

Multicenter cross-sectional study.

PARTICIPANTS

Normal white subjects.

METHODS

An approximately equal number of subjects in each decade group (20-90 years of age) was enrolled in 5 centers. Subjects had normal ocular and visual field examination results. We obtained OCT images of the optic nerve head (24 radial scans) and peripapillary retina (1 circular scan). The angle between the fovea and BMO center (FoBMO angle), relative to the horizontal axis of the image frame, was first determined and all scans were acquired and analyzed relative to this eye-specific FoBMO axis. Variation in BMO-MRW and RNFLT was analyzed with respect to age, sector, and BMO shape.

MAIN OUTCOME MEASURES

Age-related decline and between-subject variability in BMO-MRW and RNFLT.

RESULTS

There were 246 eyes of 246 subjects with a median age of 52.9 years (range, 19.8-87.3 years). The median FoBMO angle was -6.7° (range, 2.5° to -17.5°). The BMO was predominantly vertically oval with a median area of 1.74 mm(2) (range, 1.05-3.40 mm(2)). Neither FoBMO angle nor BMO area was associated with age or axial length. Both global mean BMO-MRW and RNFLT declined with age at a rate of -1.34 μm/year and -0.21 μm/year, equivalent to 4.0% and 2.1% loss per decade of life, respectively. Sectorially, the most rapid decrease occurred inferiorly and the least temporally; however, the age association was always stronger with BMO-MRW than with RNFLT. There was a modest relationship between mean global BMO-MRW and RNFLT (r = 0.35), whereas sectorially the relationship ranged from moderate (r = 0.45, inferotemporal) to nonexistent (r = 0.01, temporal).

CONCLUSIONS

There was significant age-related loss of BMO-MRW in healthy subjects and notable differences between BMO-MRW and RNFLT in their relationship with age and between each other. Adjusting BMO-MRW and RNFLT for age and sector is important in ensuring optimal diagnostics for glaucoma.

The non-human primate experimental glaucoma model

The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.

Assessment of retinal nerve fiber layer thickness in healthy, full-term neonates

PURPOSE

To measure average retinal nerve fiber layer (RNFL) thicknesses in healthy, full-term neonates.

DESIGN

Descriptive research to develop normative data.

METHODS

Healthy infants born between 37 and 42 weeks postmenstrual age were imaged with hand-held spectral-domain optical coherence tomography. A custom script segmented the RNFL; the fovea and optic nerve center were manually selected. A second script measured the average RNFL thickness along the papillomacular bundle, defined as the arc from -15 degrees to +15 degrees on the axis from the optic nerve to fovea, with radii of 1.1, 1.3, 1.5, and 1.7 mm from the center of the optic disc. Shapiro-Wilk W tests assessed these measurements for normality to determine the age-appropriate radial distance for subsequent analyses. Average RNFL thicknesses for four temporal 45-degree sectors (superior temporal, temporal superior, temporal inferior, and inferior temporal) and the temporal quadrant were calculated and compared to demographic parameters for all infants.

RESULTS

Fifty full-term infants were adequately imaged for RNFL analysis. RNFL thicknesses at 1.5 mm radial distance from the optic nerve were the most normally distributed. While there was a trend toward greater mean superior temporal RNFL thickness for both black and Hispanic vs white infants (128 ± 27 μm, 124 ± 30 μm, and 100 ± 19 μm, respectively, P = .04 for both comparisons), there were no other significant differences noted in RNFL thicknesses by race, sex, gestational age, or birth weight.

CONCLUSIONS

We present RNFL thickness measurements for healthy, full-term infants that may serve as normative data for future analyses.

Evaluating glaucoma damage: emerging imaging technologies

The use of ocular imaging tools to estimate structural and functional damage in glaucoma has become a common clinical practice and a substantial focus of vision research. The evolution of the imaging technologies through increased scanning speed, penetration depth, image registration and development of multimodal devices has the potential to detect the pathology more reliably and in earlier stages. This review is focused on new ocular imaging modalities used for glaucoma diagnosis.

Lamina cribrosa microarchitecture in normal monkey eyes part 1: methods and initial results

PURPOSE

To introduce quantitative postmortem lamina cribrosa (LC) microarchitecture (LMA) assessment and characterize beam diameter (BD), pore diameter (PD), and connective tissue volume fraction (CTVF) in 21 normal monkey eyes.

METHODS

Optic nerve heads (ONHs) underwent digital three-dimensional (3D) reconstruction and LC beam segmentation. Each beam and pore voxel was assigned a diameter based on the largest sphere that contained it before transformation to one of twelve 30° sectors in a common cylinder. Mean BD, PD, and CTVF within 12 central and 12 peripheral subsectors and within inner, middle, and outer LC depths were assessed for sector, subsector, and depth effects by analysis of variance using general estimating equations. Eye-specific LMA discordance (the pattern of lowest connective tissue density) was plotted for each parameter.

RESULTS

The ranges of mean BD, PD, and CTVF were 14.0 to 23.1 μm, 20.0 to 35.6 μm, and 0.247 to 0.638, respectively. Sector, subsector, and depth effects were significant (P < 0.01) for all parameters except subsector on CTVF. Beam diameter and CTVF were smaller and PD was larger within the superior-temporal (ST) and inferior-temporal (IT) sectors (P < 0.05). These differences were enhanced within the central versus peripheral subsectors. Beam diameter and CTVF were larger and PD was smaller (P < 0.05) within the middle LC layer. Lamina cribrosa microarchitecture discordance most commonly occurred within the ST and IT sectors, varied by eye, and generally diminished as CTVF increased.

CONCLUSIONS

Our data support previous characterizations of diminished connective tissue density within the ST and IT ONH regions. The clinical importance of eye-specific LMA discordance warrants further study.

Influence of the disc-fovea angle on limits of RNFL variability and glaucoma discrimination

PURPOSE

To determine factors affecting the disc-fovea angle (DFA), and to test the hypotheses that adjusting for DFA improves limits of retinal nerve fiber layer (RNFL) variability in normal subjects or enhances performance of RNFL measures for glaucoma detection.

METHODS

Disc-fovea angle was measured on scanning laser ophthalmoscope fundus images from 170 eyes (110 normal and glaucoma subjects). The DFA measurements were repeated in 24 eyes. The relationship between DFA and various anatomic variables was explored. Main outcome measures were changes in 95% RNFL prediction limits or glaucoma discrimination after adjusting for DFA. We also explored the angle between temporal raphe and horizontal meridian in 19 eyes with nasal field defects limited to one hemifield.

RESULTS

Average mean deviation and DFA were -0.1 (±1.2) dB and -6.6° (±3.4°) and -4.1 (±3.3) dB and -7.9° (±3.9°) in the control and glaucoma groups, respectively (P < 0.001 and = 0.029). The average difference between DFA repeat measurements was 2.0° (±1.8°). Predictors for DFA were female sex (P = 0.004), smaller disc area (P = 0.006), and glaucoma diagnosis (P = 0.019). The absolute change in sectoral RNFL thickness was 6.1 (±3.9) and 4.6 (±3.1) μm in control and glaucoma subjects, respectively. Retinal nerve fiber layer prediction limits improved in 5, 9, and 10 o'clock sectors (P < 0.02). Discrimination ability for the best-performing RNFL sector did not improve (P = 0.936). The average angle between temporal raphe and horizontal meridian was 0.8° (±0.8°).

CONCLUSIONS

Disc-fovea angle measurements demonstrated fair intersession repeatability. While adjusting for DFA improved RNFL prediction limits in some sectors, it did not enhance glaucoma detection.

Reducing variability in visual field assessment for glaucoma through filtering that combines structural and functional information

PURPOSE

To reduce variability and improve measurements of true change signal in visual field (VF) assessments through the use of filters that combine functional and structural test results.

METHODS

Humphrey VF data (Swedish Interactive Thresholding Algorithm [SITA] Standard, 24-2) and confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph [HRT]) data from 1057 eyes of 637 participants were used to derive a filter. Another dataset, consisting of VF and HRT data from 112 eyes of 62 participants each with ≥5 visits, was used to test the filter. At each VF location per eye, the trend over time was modeled by a linear model (LM), and a nonlinear model (NLM), using filtered or unfiltered data, but with the last visit excluded. The SD of residuals from the trends, and prediction errors (PE) for the last visit were compared between filtered and unfiltered data. The filter was reconstructed and analyses were repeated after truncating VF data so that thresholds < 19 dB were replaced by 19 dB to reduce noise.

RESULTS

The SD of the residuals at all 52 VF locations for all analyses was reduced by filtering (P < 0.001). The PE was reduced by filtering at 43 and 47 VF locations (P < 0.05) for LM analyses on observed and truncated data, and all 52 VF locations (P < 0.05) for both NLM analyses. Truncating data before filtering reduced variability (P < 0.01) at 41 and 40 VF locations for LM and NLM analyses.

CONCLUSIONS

Filtering can reduce variability about trends in longitudinal sequences of VF data, and improves the accuracy of predicting the next test result.