Earlier Detection of Glaucoma Progression Using High-Density 3-Dimensional Spectral-Domain OCT Optic Nerve Volume Scans

Glaucoma Progression in Treatment-Naïve Patients With Normal Tension Glaucoma With Myopia-Role of Intraocular Pressure

PRCIS

While myopia has been recognized as a positive prognostic factor for normal tension glaucoma (NTG) progression in the adult population, some myopic NTG eyes exhibited significant progression within 2 years when left untreated, even under low intraocular pressure (IOP).

OBJECTIVE

To determine the natural history and risk factors associated with progressive retinal nerve fiber layer (RNFL) thinning in previously stable, treatment-naïve, patients with NTG with myopia.

METHODS

This study included 111 myopic NTG eyes without IOP-lowering treatment for at least 1 year and without disease progression during the treatment-free period. The RNFL thickness was measured, and a visual field test was performed every 6-12 months for >2 years. Patients with progressive changes were classified as the P(+) group, whereas those without progression were classified as the P(-) group. Cox proportional hazards model assessed risk factors of progression, whereas linear regression determined factors associated with the rate of RNFL thinning.

RESULTS

Progressive change was observed in 25 of the 111 participants [P(+) group, 22.5%]. A family history of glaucoma, higher mean IOP, and maximum IOP during the follow-up were significant factors both for being in the P(+) group and for a faster RNFL thinning. None with a mean IOP <11 mm Hg were in the P(+) group. Davies test identified that 14.2 mm Hg was a significant breakpoint ( P = 0.042), above which the rate of RNFL thinning increased significantly with the mean IOP ( R2 = 0.252, P = 0.034).

CONCLUSIONS

Patients with myopic NTG untreated for IOP, especially those with a family history of glaucoma or higher IOP, are at increased risk of progression. Early treatment initiation is advised for high-risk patients with myopic NTG, even when their condition appears stable.

Frequency of Agreement Between Structural and Functional Glaucoma Testing: A Longitudinal Study of 3D OCT and Current Clinical Tests

PURPOSE

To evaluate how often tests of structure and function detect glaucoma progression at the same study visit. Tests include current glaucoma clinical tests and a new 3-dimensional (3D) optical coherence tomography (OCT) rim measurement.

DESIGN

Prospective cohort study.

METHODS

For 124 open-angle glaucoma patients at a single institution, one eye was randomly selected for each patient. Patients were included if they had open-angle glaucoma and if they had at least 4 yearly study visits. Study visits included a full dilated eye exam, disc photography (DP), Humphrey visual field (HVF 24-2) testing, 2D OCT retinal nerve fibre layer (RNFL) thickness measurements, and 3D OCT neuroretinal rim measurements (i.e., minimum distance band or MDB). For each test at each study visit, eyes were classified as progressors or non-progressors using event-based analysis. Agreement occurred if tests progressed in the same eye at the same study visit. Agreements between all compared tests were calculated as percentages of agreement.

RESULTS

The study included 124 open-angle glaucoma eyes, which had an average follow-up period of 66.9 ± 16.4 months. Structural tests (i.e., DP, global RNFL thickness, and global MDB rim thickness) progressed at the same visit as the functional test (i.e., HVF testing) in only 5.0% (3/60) to 16.0% (13/81) of eyes. Global MDB thickness and global RNFL thickness showed similar agreement with functional HVF testing (i.e., 16.0% [13/81] and 8.3% [7/84], respectively), and global MDB thickness showed better structure-function agreement with HVF testing than between DP and HVF testing (i.e., 5.0% [3/60], P = 0.04). For all paired comparisons between testing methods, eyes with moderate glaucoma showed similar or better agreement than eyes with mild or severe glaucoma.

CONCLUSIONS

Clinical tests of structure and function do not usually progress at the same clinic visit. Most of the time, glaucoma progression is only detected by one or two tests.

Diagnostic value of three-dimensional neuroretinal rim thickness for differentiation of superior segmental optic nerve hypoplasia

Little is known about the diagnostic utility of three-dimensional neuroretinal rim thickness (3D-NRRT) for differentiating patients with superior segmental optic nerve hypoplasia (SSOH) from normal-tension glaucoma (NTG). Since SSOH is defined by characteristic optic nerve head features, investigation of diagnostic usefulness of 3D-NRRT is necessary. In this cross-sectional study, 49 SSOH eyes, 52 NTG eyes, and 41 normal eyes were enrolled. Retinal nerve fiber layer thickness (RNFLT) and 3D-NRRT values, as obtained in the right-eye orientation by optical coherence tomography (OCT), were recorded. On RNFLT clock-hour comparison, the 11-3 clock-hour sectors were significantly thinner for SSOH than for NTG (all P < 0.01). As for 3D-NRRT, whereas the 1 and 2 sectors were significantly thinner for SSOH (P < 0.001, P = 0.004), the 6-11 sectors were significantly thinner for NTG (all P < 0.01). The area under receiver operating characteristic (AUROC) curves of the superior and nasal quadrants of RNFLT (0.838, 0.729) were significantly greater than those of 3D-NRRT (0.518, 0.588; P < 0.001, P = 0.043). However, the AUROCs of the inferior and temporal quadrants were significantly greater for 3D-NRRT (0.728, 0.760) than for RNFLT (0.527, 0.550; P = 0.008, P = 0.019). The appropriate use of 3D-NRRT can be useful in differentiating SSOH from NTG.

Facilitating glaucoma diagnosis with intereye neuroretinal rim asymmetry analysis using spectral-domain optical coherence tomography

Purpose

To determine whether intereye asymmetry of a three-dimensional neuroretinal rim parameter, the minimum distance band, is useful in differentiating normal eyes from those with open-angle glaucoma.

Materials and Methods

This is a cross-sectional study of 28 normal subjects and 33 glaucoma subjects. Subjects underwent spectral domain optical coherence tomography imaging of both eyes. From high-density raster scans of the optic nerve head, a custom-designed segmentation algorithm calculated mean minimum distance band neuroretinal rim thickness globally, for four quadrants, and for four sectors. Intereye minimum distance band thickness asymmetry was calculated as the absolute difference in minimum distance band thickness values between the right and left eyes.

Results

Increasing global minimum distance band thickness asymmetry was not associated with increasing age or increasing refractive error asymmetry. Glaucoma patients had thinner mean neuroretinal rim thickness values compared to normal patients (209.0 μm vs 306.0 μm [P < 0.001]). Glaucoma subjects had greater intereye thickness asymmetry compared to normal subjects for the global region (51.9 μm vs 17.6 μm [P < 0.001]) as well as for all quadrants and all sectors. For detecting glaucoma, a thickness asymmetry value >28.3 μm in the inferior quadrant yielded the greatest sum of sensitivity (87.9%) and specificity (75.0%). Globally, thickness asymmetry >30.7 μm yielded the greatest sum of sensitivity (66.7%) and specificity (89.3%).

Conclusions

This study indicates that intereye neuroretinal rim minimum distance band asymmetry measurements, using high-density spectral domain optical coherence tomography volume scans, may be an objective and quantitative tool for assessing patients suspected of open-angle glaucoma.

Reproducibility of Neuroretinal Rim Measurements Obtained from High-Density Spectral Domain Optical Coherence Tomography Volume Scans

Purpose

To compare the reproducibility of two-dimensional (2D) peripapillary retinal nerve fiber layer (RNFL) thickness and three-dimensional (3D) neuroretinal rim measurements using spectral domain optical coherence tomography (SDOCT) in normal and glaucoma subjects.

Methods

One eye per subject for 27 normal and 40 glaucoma subjects underwent repeat SDOCT RNFL thickness scans and optic nerve volume scans on the same day. From the volume scan, custom software calculated five neuroretinal rim parameters: 3D minimum distance band (MDB) thickness, 3D MDB area, 3D rim volume, 2D rim area, and 2D rim thickness. Within-subject variance (Sw), coefficient of variation (CV), and intraclass correlation coefficient (ICC) were analyzed.

Results

MDB thickness and RNFL thickness have similar reproducibility among normal and glaucoma subjects (eg, global MDB thickness CVs of 2.4% and 3.6%, and global RNFL thickness CVs of 1.3% and 2.2%; P > 0.05 for both comparisons). Reproducibility of MDB thickness was lower in glaucoma patients for the superior and inferior quadrants compared to normal subjects (CVs of 9.6% versus 3.4% and 6.9% versus 2.7%; P < 0.05, respectively). There were no statistically significant differences between both groups for RNFL thickness in the four quadrants. For both patient groups and for all regions, MDB thickness had the lowest CVs among all five neuroretinal rim parameters (eg, global MDB thickness CVs of 2.4% and 3.6% versus 3.0% and 18.9% for the other four neuroretinal rim parameters).

Conclusion

Global MDB and global RNFL thickness are similarly reproducible among normal and glaucoma subjects, though MDB thickness for the superior and inferior quadrants is less reproducible among glaucoma subjects.

Central Macular Topographic and Volumetric Measures: New Biomarkers for Detection of Glaucoma

Purpose

To test the hypothesis that newly developed shape measures using optical coherence tomography (OCT) macular volume scans can discriminate patients with perimetric glaucoma from healthy subjects.

Methods

OCT structural measures defining macular topography and volume were recently developed based on cubic Bézier curves. We exported macular volume scans from 135 eyes with glaucoma (133 patients) and 155 healthy eyes (85 subjects) and estimated global and quadrant-based measures. The best subset of measures to predict glaucoma was explored with a gradient boost model (GBM) with subsequent logistic regression. Accuracy and area under receiver operating curves (AUC) were the primary metrics. In addition, we separately investigated model performance in 66 eyes with mild glaucoma (mean deviation ≥ -6 dB).

Results

Average (±SD) 24-2 mean deviation was -8.2 (±6.1) dB in eyes with glaucoma. The main predictive measures for glaucoma were temporal inferior rim height, nasal inferior pit volume, and temporal inferior pit depth. Lower values for these measures predicted higher risk of glaucoma. Sensitivity, specificity, and AUC for discriminating between healthy and glaucoma eyes were 81.5% (95% CI = 76.6-91.9%), 89.7% (95% CI = 78.7-94.2%), and 0.915 (95% CI = 0.882-0.948), respectively. Corresponding metrics for mild glaucoma were 84.8% (95% CI = 72.1%-95.5%), 85.8% (95% CI = 87.1%-97.4%), and 0.913 (95% CI = 0.867-0.958), respectively.

Conclusions

Novel macular shape biomarkers detect early glaucoma with clinically relevant performance. Such biomarkers do not depend on intraretinal segmentation accuracy and may be helpful in eyes with suboptimal macular segmentation.

Translational Relevance

Macular shape biomarkers provide valuable information for detection of early glaucoma and may provide additional information beyond thickness measurements.

New views on three-dimensional imaging technologies for glaucoma: an overview

PURPOSE OF REVIEW

To summarize the literature on three-dimensional (3D) technological advances in ophthalmology, the quantitative methods associated with this, and their improved ability to help detect glaucoma disease progression.

RECENT FINDINGS

Improvements in measuring glaucomatous structural changes are the result of dual innovations in optical coherence tomography (OCT) imaging technology and in associated quantitative software.

SUMMARY

Compared with two-dimensional (2D) OCT parameters, newer 3D parameters provide more data and fewer artifacts.

Disc Hemorrhages Are Associated With Localized Three-Dimensional Neuroretinal Rim Thickness Progression in Open-Angle Glaucoma

PURPOSE

To evaluate the relationship between the occurrence of optic disc hemorrhages (DH) and glaucoma progression as determined by multiple glaucoma testing modalities.

DESIGN

Prospective cohort study.

METHODS

A longitudinal study was undertaken of 124 open-angle glaucoma patients who had yearly disc photography, visual fields (VFs), spectral-domain optical coherence tomography (SD-OCT), retinal nerve fiber layer (RNFL) thickness scans, and optic nerve volume scans (Spectralis), all performed on the same day over a 5-year period. The minimum distance band (MDB) thickness, a 3-dimensional (3D) neuroretinal rim parameter, was calculated from optic nerve volume scans. Patients were classified as glaucoma progressors or glaucoma nonprogressors using event-based analysis.

RESULTS

Of 124 open-angle glaucoma patients, 19 (15.3%) had 1 or more DHs on yearly disc photographs. Presence of a DH was associated with localized 3D neuroretinal rim thickness progression (superior MDB progression; odds ratio: 3.96; P = .04) but not with global or inferior MDB progression (P = .14 and .81, respectively), DP progression (P = .08), VF progression (P = .45), or RNFL global, inferior, or superior progression (P = .17, .26, and .76, respectively). In the majority of patients with MDB progression (14/17 or 82%), the progression was noted before or concurrently with the first instance of DH.

CONCLUSIONS

Glaucoma progression detected by high-density 3D SD-OCT neuroretinal rim measurements preceded DH occurrence in the majority of patients. These findings support the hypothesis that DHs are indicators of ongoing glaucoma progression rather than discrete events that cause subsequent progression.