A comparison of rates of change in neuroretinal rim area and retinal nerve fiber layer thickness in progressive glaucoma

Accuracy of Bruch's membrane opening minimum rim width and retinal nerve fiber layer thickness in glaucoma diagnosis depending on optic disc size

BACKGROUND/AIM

The aim of this paper is to compare retinal nerve fiber layer thickness (RNFL) and Bruch's membrane opening-based minimum rim width (BMO-MRW) in terms of their performance in detecting early and moderate/advanced glaucoma using receiver operating characteristics (ROC) analysis and the classification using the 5th percentile as a cut-off.

METHODS

One hundred eyes from 100 patients with early glaucoma (mean deviation (MD): < -5.0 dB) and 100 eyes from 100 patients with moderate/advanced glaucoma (MD: > -5.0 dB) were carefully matched to healthy controls based on optic disc size. Then, the dataset was divided, based on the 50th percentile of the measured Bruch's membrane opening area (BMO-A), into small (BMO-A < 1.95 mm2) and large optic discs (BMO-A > 1.95 mm2). Finally, the discriminative performance of BMO-MRW and RNFL between glaucoma and controls using ROC analysis and the manufacturer's classification based on the 5th percentile was analyzed.

RESULTS

In discriminating between glaucoma and matched healthy controls, global BMO-MRW and global RNFL thickness had comparable areas under the ROC curve for eyes with early glaucoma and both small BMO-As (ROC ± confidence interval [CI] 0.91 [0.87 to 0.95] and 0.88 [0.83 to 0.93]) and large BMO-As (0.86 [0.82 to 0.92] and 0.84 [0.79 to 0.90]), as well as in moderate/advanced glaucoma with small BMO-As (0.99 [0.98 to 1.00] and 0.97 [0.95 to 1.00]) and large BMO-As (0.94 [0.91 to 0.98] and 0.97 [0.94 to 1.00]). Using the calculated 5th percentile as a threshold value, the sensitivities for the detection of early and moderate/advanced glaucoma were comparable for BMO-MRW and RNFL in eyes with small optic discs (early glaucoma: fifty-two percent and 61%; moderate/advanced glaucoma: ninety-one percent and 92%). In eyes with large optic discs, the sensitivity of BMO-MRW was inferior to that of RNFL for both early (38% versus 51%) and moderate/advanced (80% versus 91%) glaucoma.

CONCLUSION

Based on an ROC analysis, the discriminative performance of BMO-MRW and RNFL between patients with early and moderate/advanced glaucoma and a healthy control group matched based on optic disc size is comparable in eyes with BMO-As smaller and larger 1.95 mm2. Using a classification based on the 5th percentile, as used in clinical practice, RNFL is shown to be superior to BMO-MRW regarding sensitivity in glaucoma detection with large optic discs. This study underscores the importance of RNFL imaging and measurement in the diagnostic evaluation of glaucoma, especially in cases of large optic discs.

Racial-ethnic disparities in concurrent rates of peripapillary & macular OCT parameters among a large glaucomatous clinical population

OBJECTIVES

To compare rates of change in peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) parameters among different race-ethnicities from a large electronic health record database of subjects with or suspected of glaucoma.

METHODS

In this retrospective cohort study, rates of change were obtained using joint longitudinal linear mixed models for eyes with ≥3 visits and ≥1 year of follow-up, adjusting for age, sex, intraocular pressure, central corneal thickness, and baseline pRNFL and mGCIPL thickness. Best linear unbiased predictor estimates of various parameters were stratified by baseline glaucoma severity and analysed by racial-ethnic group.

RESULTS

A total of 21,472 spectral domain optical coherence tomography (OCT) pRNFL scans and 14,431 mGCIPL scans from 2002 eyes were evaluated. A total of 200 (15.6%) and 601 (46.8%) subjects identified as non-Hispanic Black (NHB) and Hispanic, respectively. NHB eyes exhibited faster rates of change in pRNFL among glaucoma suspect (global pRNFL -0.57 ± 0.55 µm/year vs. -0.37 ± 0.62 µm/year among Hispanics, p < 0.001), mild glaucoma (superior pRNFL quadrant -1.20 ± 1.06 µm/year vs. -0.75 ± 1.51 µm/year among non-Hispanic Whites (NHW), p = 0.043), and moderate glaucoma eyes (superior pRNFL quadrant -1.31 ± 1.49 µm/year vs. -0.52 ± 1.26 µm/year among Hispanics, p = 0.003). NHB eyes exhibited faster rates of mGCIPL loss corresponding to pRNFL rates. Global pRNFL and mGCIPL rates were strongly correlated (R2 = 0.70).

CONCLUSIONS

Adjusted rates of pRNFL and mGCIPL loss significantly differed between racial-ethnic groups when stratified by glaucoma severity, with faster rates among NHB patients. These differences highlight key racial-ethnic disparities in adjusted rates of glaucoma OCT parameters.

Association of an Objective Structural and Functional Reference Standard for Glaucoma with Quality of Life Outcomes

PURPOSE

To compare self-reported quality-of-life (QoL) outcomes of patients diagnosed as normal, glaucoma suspect, and glaucoma based on an objective reference standard for glaucomatous optic neuropathy (GON).

DESIGN

Cross-sectional study.

PARTICIPANTS

1884 eyes of 1019 patients were included in the study.

METHODS

The data was sourced from the Duke Glaucoma Registry. Eyes were classified according to the presence and topographic correspondence of functional and structural damage, as assessed by parameters from standard automated perimetry (SAP) and spectral-domain OCT (SD-OCT). The objective diagnosis of the worse eye was used to define patient-level diagnosis. To assess QoL in the diagnostic groups, 14 unidimensional vision-related items of the National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) were used to assess QoL in the diagnostic groups. Association between NEI VFQ-25 Rasch-calibrated scores and diagnostic groups was assessed through multivariable regression that controlled for confounding demographic and socioeconomic variables such as age, sex, race, income, marriage status, insurance status, and highest education level.

MAIN OUTCOME MEASURES

NEI VFQ-25 Rasch scores compared with objective criteria diagnosis based on SAP mean deviation (MD) and SD-OCT retinal nerve fiber layer (RNFL) thickness.

RESULTS

Overall, eyes classified as normal, glaucoma suspect, and glaucoma had decreasing mean scores in SAP MD (0.2 ± 1.0 dB, -0.9 ± 2.4 dB, -6.2 ± 7.0 dB, respectively; P < 0.001) and SD-OCT RNFL thickness (97.8 ± 9.5 μm, 89.0 ± 13.1 μm, 64.5 ± 12.8 μm, respectively; P < 0.001). The mean Rasch-calibrated NEI VFQ-25 score was significantly different among normal, suspect, and glaucoma groups (82.9 ± 13.0, 78.2 ± 14.8, and 72.6 ± 16.2, respectively; P < 0.001). When adjusted for confounding socioeconomic variables, glaucoma patients had significantly worse QoL than those classified as normal (β = -6.8 Rasch score units; P < 0.001).

CONCLUSION

A glaucoma diagnosis, based on an objective reference standard for GON, was significantly associated with worse Rasch-adjusted scores of QoL. Utilization of such objective criteria may provide clinically relevant metrics with potential to improve comparability of research findings and validation of newly proposed diagnostic tools.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Screening fundus photography predicts and reveals risk factors for glaucoma conversion in eyes with large optic disc cupping

This study aimed to investigate the risk factors for glaucoma conversion and progression in eyes with large optic disc cupping without retinal nerve fiber layer defect (RNFLD). Five hundred forty-two eyes of 271 subjects who had a vertical cup-to-disc ratio (CDR) ≥ 0.6 without RNFLD were enrolled. Characteristics for optic disc configuration (including CDR, vertical cupping, ISNT rule, disc ovality, peripapillary atrophy [PPA]-to-disc area [DA] ratio, and lamina cribrosa pore visibility) and blood vessels (including central retinal vessel trunk [CRVT] nasalization, bayoneting of vessels, baring of circumlinear vessels, history of disc hemorrhage [DH] and vessel narrowing/sclerotic change) were evaluated. From a median follow-up of 11.3 years, 26.6% of eyes (n = 144) developed RNFLD within a median of 5.1 years. Baseline factors, including vertical CDR ≥ 0.7 (hazard ratio [HR] = 2.12), vertical cupping (HR = 1.93), ISNT rule violation (HR = 2.84), disc ovality ≥ 1.2 (HR = 1.61), PPA-to-DA ratio ≥ 0.4 (HR = 1.77), CRVT nasalization ≥ 60% (HR = 1.77), vessel narrowing/sclerotic change (HR = 2.13), DH history (HR = 5.60), and baseline intraocular pressure ≥ 14 mmHg (HR = 1.70) were significantly associated with glaucoma conversion (all Ps < 0.05). An HR-matched scoring system based on initial fundus photography predicted glaucoma conversion with specificity of 90.4%. Careful examination of the optic nerve head and vascular structures can help to predict the risk of glaucoma conversion in eyes with large optic disc cupping.

Optic Disc Microvasculature Dropout in Glaucoma Detected by Swept-Source Optical Coherence Tomography Angiography

PURPOSE

To assess the clinical utility of swept-source optical coherence tomography angiography (SS-OCTA) in detecting optic disc microvasculature dropout (MvD-D) in primary open-angle glaucoma (POAG) eyes.

DESIGN

Cross-sectional study.

METHODS

The study enrolled 197 eyes of 197 patients with POAG with acceptable-quality SS-OCTA (PLEX Elite 9000; Carl Zeiss Meditec) images. A whole-signal-mode 6.0- × 6.0-mm optic disc cube was obtained with projection artifact removal. Three groups were categorized: no MvD-D (group 1), MvD-D (group 2, complete loss of microvasculature within the optic disc), and indiscernible MvD-D (group 3, poor visualization of the anterior lamina cribrosa [LC]).

RESULTS

There were 82 (42.1%) and 81 (41.5%) eyes categorized as no MvD-D (group 1) and MvD-D (group 2), respectively. The remaining 32 eyes (16.4%), categorized as indiscernible MvD-D (group 3), had a significantly smaller anterior scleral canal opening (ASCO) area (P < .05). Group 2 had significantly worse visual field (VF) mean deviation (MD), thinner average retinal nerve fiber layer (RNFL), higher prevalence of focal LC defect, and parapapillary deep-layer microvasculature dropout (MvD-P) than the other 2 groups (P < .05). In the multivariable logistic regression analysis, higher prevalence of focal LC defect (odds ratio, 46.91; P < .001) and MvD-P (odds ratio, 48.94; P < .001) remained as factors associated with MvD-D.

CONCLUSIONS

The presence of MvD-D could be well determined by SS-OCTA in eyes with POAG. MvD-P and focal LC defects were strongly associated with MvD-D. This suggests that SS-OCTA can serve as a useful tool in detecting optic disc microvasculature damage.

Macular Thickness and Microvasculature Loss in Glaucoma Suspect Eyes

PURPOSE

To characterize the change of ganglion cell complex (GCC) thickness and macular vessel density in glaucoma suspect eyes with ocular hypertension (OHT) or glaucomatous optic neuropathy (GON).

DESIGN

Prospective, longitudinal study.

PARTICIPANTS

Eight-three eyes (24 healthy, 30 OHT, and 29 GON) of 65 patients who underwent at least 3 visits were included from the Diagnostic Innovations in Glaucoma Study. The mean follow-up was at least 3 years.

METHODS

OCT angiography (OCTA)-based vessel density and OCT-based structural thickness of the 3 × 3-mm¹ GCC scan slab were evaluated at each visit. The rates of vessel density and thickness change were compared across diagnostic groups using a linear mixed-effects model.

MAIN OUTCOME MEASURES

Change rates of macula GCC thickness and superficial vessel density.

RESULTS

Significant mean rates of both GCC thinning and vessel density loss were detectable in OHT and GON groups. Of the individual suspect eyes, 49.1% showed significant loss (P < 0.05) with either vessel density or GCC thickness. Of the GON eyes, 31.0% showed both significant GCC loss and vessel density loss, 51.7% showed only significant GCC loss, whereas 17.2% showed only significant vessel density loss. Vessel density loss was faster than GCC thinning in half of the suspect eyes based on percent loss analysis. The age and scan quality-adjusted GCC thinning rates of the OHT group (-0.59 μm/year; P = 0.025) and GON group (-0.79 μm/year; P = 0.058) were faster than those of the healthy group (-0.11 μm/year), whereas the rate of vessel density loss was not significantly different among the diagnostic groups (all P > 0.2). Higher mean intraocular pressure during follow-up was associated with faster GCC thinning in the OHT group (P = 0.065) and GON groups (P = 0.015), but was not associated with the rate of vessel density decrease.

CONCLUSIONS

Whereas the rate of GCC thinning was faster on average in suspect eyes than in healthy eyes, some suspect eyes showed significant loss of vessel density and faster vessel density loss than GCC thinning. OCT and OCTA are complementary and useful for evaluating eyes with OHT or GON.

Agreement Between Trend-Based and Qualitative Analysis of the Retinal Nerve Fiber Layer Thickness for Glaucoma Progression on Spectral-Domain Optical Coherence Tomography

INTRODUCTION

To evaluate the agreement between trend-based analysis and qualitative assessment of the retinal nerve fiber layer (RNFL) thickness for glaucomatous progression on spectral-domain optical coherence tomography (SDOCT).

METHODS

Retrospective review of 190 eyes from 103 patients with glaucoma or suspected glaucoma that underwent SDOCT imaging during four consecutive clinic visits. Trend-based progression was characterized by a significantly negative slope. Progression by qualitative analysis was determined by review of raw SDOCT B-scans.

RESULTS

The slope was significantly greater in those with progression than without progression for both trend-based and qualitative analysis (p < 0.001). However, the qualitative grading classified a significantly greater proportion of eyes as progressing compared to trend-based analysis in both the superotemporal (ST) (23.2% vs. 10.5%, p = 0.001) and inferotemporal (IT) RNFL (27.4% vs 8.4%, p < 0.001). The trend-based and qualitative classifications of progression showed poor agreement in both the ST (kappa = 0.0135) and IT RNFL (kappa = 0.1222). The agreement between trend-based and qualitative analysis was lower for eyes with artifacts (ST = 58.11%; IT = 68.7%) than those without artifacts (ST = 80.2%; IT = 74.8%). Moreover, among eyes with artifacts, there was no significant difference in slope between those qualitatively categorized as progressing versus not progressing (p > 0.05).

CONCLUSIONS

Poor agreement was found between a trend-based and qualitative analysis of change in RNFL on SDOCT. Careful qualitative review of SDOCT imaging may identify specific areas of glaucoma progression not captured by trend-based methods, especially in the presence of artifacts. Such an approach may also prove useful for detecting glaucoma progression in a clinical setting when there are few data points available.

Capillary Density Measured by Optical Coherence Tomography Angiography in Glaucomatous Optic Disc Phenotypes

PURPOSE

To compare optical coherence tomography angiography (OCTA)-measured capillary density of the optic disc among 4 glaucomatous optic disc phenotypes.

DESIGN

Cross-sectional study.

METHODS

Circumpapillary capillary density (cpCD) of 4 glaucomatous optic disc phenotypes in 193 eyes of 141 glaucoma patients and cpCD in 92 eyes of 55 healthy subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared. Areas under the receiver operating characteristic (AUROC) curves were used to evaluate diagnostic accuracy among groups after adjusting for confounders.

RESULTS

Four glaucoma phenotypes were assessed: focal ischemic (n = 45), generalized cup enlargement (n = 60), myopic glaucoma (n = 38), and senile sclerotic (n = 50). Sex, mean ocular perfusion pressure, intraocular pressure, mean deviation, and the quality score did not differ among phenotypes. However, there were differences in age (P = .050), race (P = .039), axial length (P = .033), and retinal nerve fiber layer thickness (P < .001) among the groups. After adjusting for confounders, senile sclerotic discs had the lowest cpCD (37.1% [95% confidence interval, 35.3-38.8]), followed by focal ischemic (41.8% [40.0-43.6]), myopic glaucoma (42.1% [40-44.2]), and generalized cup enlargement (45.5% [44-47]) (P < .001) discs. The adjusted AUROC curves of cpCD for discriminating between healthy and glaucomatous eyes were highest in senile sclerotic eyes (0.928) and lowest in generalized cup enlargement eyes (0.704).

CONCLUSIONS

OCTA-measured vessel density differs among optic disc phenotypes. Clinicians should be aware that the performance of OCTA for glaucoma diagnosis may be influenced by the optic disc phenotype.

Comparison of Peripapillary Capillary Density in Glaucoma Patients of African and European Descent

PURPOSE

To evaluate racial differences in optic nerve head peripapillary capillary density measured by OCT angiography (OCTA) in patients with open-angle glaucoma.

DESIGN

Observational, cross-sectional study.

PARTICIPANTS

Two hundred eighty-four eyes of 195 glaucoma patients and 108 eyes of 58 healthy participants from the Diagnostic Innovations in Glaucoma Study.

METHODS

Global and sectoral circumpapillary capillary density (cpCD) loss in participants of European descent (ED) and African descent (AD) were compared. Areas under the receiver operating characteristic curve (AUROCs) were used to evaluate diagnostic accuracy of cpCD and global circumpapillary retinal nerve fiber layer (cpRNFL) thickness in the 2 groups after adjusting for confounders.

MAIN OUTCOME MEASURES

Peripapillary capillary density and cpRNFL thickness measurements and their estimated loss.

RESULTS

Participants of AD and ED with glaucoma were of similar age and glaucoma severity. After adjusting for age, disc area, and other confounders, significantly lower cpCD was found in ED eyes compared with AD eyes in mild glaucoma (mean, 42.2% [95% confidence interval (CI), 41.2%-43.2%] and 46.5% [95% CI, 44.8%-48.1%], respectively; adjusted difference, 4.4 [95% CI, 2.6-6.2]; P < 0.001) and moderate to advanced glaucoma (mean, 34.7% and 38.5%, respectively; adjusted difference, 4.8 [95% CI, 1.6-8.1]; P = 0.005). Although capillary density loss was greater in all sectors in ED compared with AD participants, a similar sectoral pattern of density loss was observed in both racial groups. Lower mean deviation and older age were associated with lower cpCD in both races in multivariate models. The adjusted AUROC for discriminating between healthy and glaucomatous eyes for cpCD was higher for ED (0.95) compared with AD (0.68) patients (P < 0.001). Sensitivity at 95% specificity in AD participants was lower than in ED participants for cpCD (0.32 [95% CI, 0.11-0.64] vs. 0.83 [95% CI, 0.69-0.93], respectively; P < 0.001).

CONCLUSIONS

Although peripapillary capillary density parameters showed good diagnostic accuracy for detecting glaucoma in ED patients, their diagnostic accuracy was only modest in AD patients. Diagnostic performance of cpCD is race dependent, and clinicians should be aware that it has poorer performance in AD patients.

A framework for assessing glaucoma progression using structural and functional indices jointly

Purpose

While many tests and indices are available to identify glaucoma progression, using them in combinations may decrease overall specificity. The aim of this study was to develop a framework for assessing glaucoma progression using structural and functional indices jointly for a fixed specificity.

Methods

The study included 337 eyes of 207 patients with ocular hypertension or primary open-angle glaucoma selected from the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study. All patients had at least 9 visits. Each visit had retinal nerve fiber layer thickness (RNFLT) and mean sensitivity from static automated perimetry (SAP MS) measured within a one-month window. Simple linear regression was applied to assess deterioration in each index for series of 5 to 9 visits. To identify progression using the two indices jointly, marginal significance levels set at a specificity of 95% were derived for two criteria: ANY (worsening on either RNFLT or SAP MS) and ALL (worsening on both RNFLT and SAP MS). Positive rate (percentage of eyes flagged as progressing) was determined individually for each index, as well as for the ANY and ALL criteria.

Results

Compared to SAP MS, RNFLT had higher positive rates (15% to 45%) for all series lengths. For the joint analyses, the positive rate was on average 12% higher for the ANY criterion compared to the ALL criterion. While RNFLT-alone had comparable positive rates and time-to-detection as the ANY criterion, each uniquely identified a subset of eyes (Kappa = 0.55 to 0.75).

Conclusions

This study provides a simple framework for assessing glaucoma progression with data from two tests jointly, without compromising specificity. This framework can be extended to include two or more parameters, can accommodate global or regional indices, and can eventually be used with novel parameters identified as predictive of glaucoma progression.

Rate of three-dimensional neuroretinal rim thinning in glaucomatous eyes with optic disc haemorrhage

Background

To investigate the thinning rate of three-dimensional neuroretinal rim thickness (3D-NRT) in glaucoma eyes with optic disc haemorrhage (DH) and its relationship to retinal nerve fibre layer thickness (RNFLT) progression.

Methods

Ninety-five (95) eyes of 95 glaucoma patients with initial DH in the inferotemporal (n=69) and superotemporal (n=26) regions and 48 eyes of 48 glaucoma patients without DH were retrospectively reviewed. The rates of change for 3D-NRT and RNFLT were compared by linear mixed-effect model. For the direct comparison between 3D-NRT and RNFLT, dynamic-range-based normalised coefficient was used. The effect of DH frequency on the rates of thinning of 3D-NRT and RNFLT was evaluated.

Results

During a mean 7-year follow-up, the rates of thinning of 3D-NRT (–5.69±4.88 µm/year) and RNFLT (–2.03±2.03 µm/year) at 7 o’clock were faster than those at other locations (all p<0.05) in DH eyes. The dynamic-range-based normalised rate of thinning was significantly faster for RNFLT (–2.06%±1.62%/year) than for 3D-NRT (–1.15%±1.10%/year, p<0.001) in DH eyes, but not in non-DH eyes (p=0.43). DH frequency in the inferotemporal region was associated with the thinning rate of 3D-NRT as well as RNFLT.

Conclusion

DH eyes are associated with the progression of both 3D-NRT and RNFLT, especially in the inferotemporal region. DH eyes show a relatively faster thinning rate of average RNFLT than 3D-NRT. The frequency of DH can affect the progression of 3D-NRT as well as RNFLT.

Macula Vessel Density and Thickness in Early Primary Open-Angle Glaucoma

PURPOSE

To characterize and compare the ganglion cell complex (GCC) thickness and macula vessel density in preperimetric and early primary open-angle glaucoma (POAG) eyes.

DESIGN

Cross-sectional study.

METHODS

Fifty-seven healthy, 68 preperimetric, and 162 early POAG eyes enrolled in the Diagnostic Innovations in Glaucoma Study. Optical coherence tomography angiography (OCT-A)-based superficial macula vessel density and OCT-based GCC thickness were evaluated simultaneously. Percent loss from normal of GCC thickness and macula vessel density was compared. Area under the receiver operating characteristic curve was used to describe the diagnostic utility.

RESULTS

Both GCC thickness and vessel density were significantly lower in preperimetric and early POAG eyes compared to healthy eyes. Compared to the preperimetric POAG group, the early POAG group showed larger GCC thickness percent loss (whole image 4.72% vs 9.86%; all P < .01) but similar vessel density percent loss (whole image 4.97% vs 6.93%; all P > .05). In preperimetric POAG, GCC thickness and vessel density percent losses were similar (all P > .1). In contrast, in early POAG, GCC thickness percent loss was larger than that of vessel density (all P ≤ .001). To discriminate preperimetric or early glaucoma eyes from healthy eyes, GCC thickness and macula vessel density showed similar diagnostic accuracy (all P > .05).

CONCLUSIONS

Both GCC thinning and macula vessel density dropout were detectable in preperimetric and early POAG eyes. GCC loss was greater than macula vessel density loss in early perimetric POAG. However, OCT-A and OCT measurements showed similar efficiency to detect early glaucoma.

Long-term Changes in Anterior Segment Characteristics of Eyes With Different Primary Angle-Closure Mechanisms

PURPOSE

To assess long-term changes in the anterior segment (AS) of eyes with different angle-closure mechanisms.

DESIGN

Retrospective cohort study.

METHODS

In total, 133 eyes (from 75 participants) with angle closure were enrolled. All eyes received laser iridotomy (LI) during the follow-up period. Serial anterior segment optical coherence tomography (AS-OCT) imaging was performed during a mean follow-up of 4 years. Participants were categorized into 4 groups according to angle-closure mechanisms, based on baseline AS-OCT images: pupillary block (PB), plateau iris configuration (PIC), thick peripheral iris roll (TPIR), and exaggerated lens vault (ELV). Linear mixed-effect models were applied to evaluate the longitudinal changes in AS-OCT parameters (anterior chamber depth [ACD], lens vault [LV], and angle opening distance [AOD]).

RESULTS

Forty-six eyes (35%) were classified as PB, 30 (23%) as PIC, 34 (26%) as TPIR, and 23 (17%) as ELV. The follow-up period was 41-54 months. At baseline, ACD was shallowest in ELV, followed by PB, TPIR, and PIC, in order. The PIC group showed significantly wider AOD than the other groups at baseline. ACD decreased and LV increased over time in all groups, especially in the PIC group. After LI, the angle widened in the PB and TPIR groups, but not in the PIC and ELV groups.

CONCLUSIONS

AS parameters changed differently in the 4 groups. The effects of LI on AOD also differed among groups. Identification of the angle-closure mechanism may help predict progressive changes in AS parameters in eyes with angle closure.

[Structural endpoints for glaucoma studies]

BACKGROUND

Structural endpoints have been discussed as surrogate endpoints for the approval of neuroprotective drugs in glaucoma.

OBJECTIVE

Is the evidence strong enough to establish structural endpoints as surrogate endpoints?

MATERIAL AND METHODS

Review of current understanding between structure and function in glaucoma.

RESULTS

The introduction of optical coherence tomography has revolutionized imaging in glaucoma patients. Clinically either the nerve fiber layer thickness can be measured along a circle centered in the optic nerve head or the ganglion cell layer thickness can be assessed in the macular region, the latter being quantified in combination with other inner retinal layers. On a microscopic level there is a strong correlation between structural and functional loss but this relation can only partially be described with currently available clinical methods. This is particularly true for longitudinal course of the disease in glaucoma patients. Novel imaging techniques that are not yet used clinically may have the potential to increase our understanding between structure and function in glaucoma but further research in this field is required.

CONCLUSION

The current evidence does not allow the establishment of structural endpoints as surrogate endpoints for phase 3 studies in glaucoma. Neuroprotective drugs have to be approved on the basis of visual field data because this is the patient-relevant endpoint. Structural endpoints can, however, play an important role in phase 2 and proof of concept studies.

Progressive Macula Vessel Density Loss in Primary Open-Angle Glaucoma: A Longitudinal Study

PURPOSE

To characterize the rate of macula vessel density loss in primary open-angle glaucoma (POAG), glaucoma-suspect, and healthy eyes.

DESIGN

Longitudinal, observational cohort from the Diagnostic Innovations in Glaucoma Study.

METHODS

One hundred eyes (32 POAG, 30 glaucoma-suspect, and 38 healthy) followed for at least 1 year with optical coherence tomography angiography (OCT-A) imaging on at least 2 visits were included. Vessel density was calculated in the macula superficial layer. The rate of change was compared across diagnostic groups using a multivariate linear mixed-effects model.

RESULTS

Baseline macula vessel density was highest in healthy eyes, followed by glaucoma-suspect and POAG eyes (P < .01). The rate of vessel density loss was significantly different from zero in the POAG, but not in the glaucoma-suspect or healthy eyes. The mean rate of change in macula whole en face vessel density was significantly faster in glaucoma eyes (-2.23%/y) than in glaucoma-suspect (0.87%/y, P = .001) or healthy eyes (0.29%/y, P = .004). Conversely, the rate of change in ganglion cell complex (GCC) thickness was not significantly different from zero in any diagnostic group, and no significant differences in the rate of GCC change among diagnostic groups were found.

CONCLUSIONS

With a mean follow-up of less than 14 months, eyes with POAG had significantly faster loss of macula vessel density than either glaucoma-suspect or healthy eyes. Serial OCT-A measurements also detected glaucomatous change in macula vessel density in eyes without evidence of change in GCC thickness.

5-year disease progression of patients across the glaucoma spectrum assessed by structural and functional tools

Background

Assessment of spectral-domain optical coherence tomography (SD-OCT) compared with visual fields, to detect progression across the glaucoma spectrum.

Methods

In this study, adult glaucoma suspects and patients, with baseline retinal nerve fibre layer (RNFL) thickness on SD-OCT and reliable visual field (VF) tests on Humphrey Field Analyser (HFA) prior to March 2010, were recruited. Functional and structural progression over at least 5 years was compared using Glaucoma Progression Analysis (GPA) and VF index (VFI) on HFA and Guided Progression Analysis (GPA-OCT) on SD-OCT, respectively. Agreement of progression detection between the two modalities was computed using κ statistics.

Results

122 subjects (63 glaucoma suspects; 59 glaucoma patients) were enrolled. Of 18 suspects who progressed to glaucoma, 13 showed progression by GPA-OCT, 4 by GPA, 7 by VFI and 2 were concordant. In the 14 glaucoma patients who progressed, GPA-OCT detected progression in 6, GPA in five and VFI in six. GPA-OCT had poor agreement with GPA in glaucoma suspects (Kappa 0.15; p=0.13) and patients (Kappa 0.10; p=0.45). VFI had better agreement with GPA-OCT in glaucoma suspects (Kappa 0.34; p=0.01) than glaucoma patients (Kappa 0.12; p=0.36). Progressors by VF in both groups had similar percentage change from baseline RNFL thickness (−9.9% vs −8.6% p=0.46), even though the absolute change was significantly greater in suspects(−8.75µ vs−6.4µ p=0.03).

Conclusion

Structural change appears to be more useful to detect progression in glaucoma suspects, while functional change is a better indicator as the disease progresses. Percentage change from baseline RNFL thickness was a better measure than absolute change in RNFL.

Comparing the Rates of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Loss in Healthy Eyes and in Glaucoma Eyes

PURPOSE

To compare the rates of circumpapillary retinal nerve fiber layer (RNFL) and macular retinal ganglion cell-inner plexiform layer (GCIPL) change over time in healthy and glaucoma eyes.

DESIGN

Cohort study.

METHODS

The rates of circumpapillary RNFL and macular GCIPL loss in 28 healthy subjects and 97 glaucoma subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared using mixed-effects models.

RESULTS

The median follow-up time and number of visits were 1.7 years and 6 visits and 3.2 years and 7 visits for healthy and glaucoma eyes, respectively. Significant rates of loss of both global circumpapillary RNFL and average macular GCIPL thickness were detectable in early and moderate glaucoma eyes; in severe glaucoma eyes, rates of average macular GCIPL loss were significant, but rates of global circumpapillary RNFL loss were not. In glaucoma eyes, mean rates of global circumpapillary RNFL thickness change (-0.98 μm/year [95% confidence interval (CI), -1.20 to -0.76]) and normalized global circumpapillary RNFL change (-1.7%/year [95% CI, -2.1 to -1.3]) were significantly faster than average macular GCIPL change (-0.57 μm/year [(95% CI, -0.73 to -0.41]) and normalized macular GCIPL change (-1.3%/year [95% CI, -1.7 to -0.9]). The rates of global and inferior RNFL change were weakly correlated with global and inferior macular GCIPL change (r ranges from 0.16 to 0.23, all P < .05).

CONCLUSIONS

In this cohort, the rate of circumpapillary RNFL thickness change was faster than macular GCIPL change for glaucoma eyes. Global circumpapillary RNFL thickness loss was detectable in early and moderate glaucoma, and average macular GCIPL thickness loss was detectable in early, moderate, and severe glaucoma, suggesting that structural changes can be detected in severe glaucoma.

Adaptive optics optical coherence tomography in glaucoma

Since the introduction of commercial optical coherence tomography (OCT) systems, the ophthalmic imaging modality has rapidly expanded and it has since changed the paradigm of visualization of the retina and revolutionized the management and diagnosis of neuro-retinal diseases, including glaucoma. OCT remains a dynamic and evolving imaging modality, growing from time-domain OCT to the improved spectral-domain OCT, adapting novel image analysis and processing methods, and onto the newer swept-source OCT and the implementation of adaptive optics (AO) into OCT. The incorporation of AO into ophthalmic imaging modalities has enhanced OCT by improving image resolution and quality, particularly in the posterior segment of the eye. Although OCT previously captured in-vivo cross-sectional images with unparalleled high resolution in the axial direction, monochromatic aberrations of the eye limit transverse or lateral resolution to about 15-20 μm and reduce overall image quality. In pairing AO technology with OCT, it is now possible to obtain diffraction-limited resolution images of the optic nerve head and retina in three-dimensions, increasing resolution down to a theoretical 3 μm3. It is now possible to visualize discrete structures within the posterior eye, such as photoreceptors, retinal nerve fiber layer bundles, the lamina cribrosa, and other structures relevant to glaucoma. Despite its limitations and barriers to widespread commercialization, the expanding role of AO in OCT is propelling this technology into clinical trials and onto becoming an invaluable modality in the clinician's arsenal.

Variance components in confocal scanning laser tomography measurements of neuro-retinal rim area and the effect of repeated measurements on the power to detect loss over time

PURPOSE

To estimate the variation in measurements of neuro-retinal rim area (NRA) determined by confocal scanning laser tomography and consequences for clinical follow-up.

METHODS

Altogether, 24 healthy subjects were randomized on -320 μm, Moorfields and Standard NRA plane strategies. Additionally, NRA was measured in 32 glaucoma subjects. Variance components for subjects, visits and measurements were estimated with analysis of variance. Sample sizes required to detect a 6.0 × 10^-2  mm² NRA change were estimated assuming a significance level of 0.05 and a power of 0.8. Consequences for independent group, and paired comparison design, respectively, were analysed. Further, precision in estimates within subjects over time was investigated.

RESULTS

The variation of NRA among subjects was considerably larger than the variation among visits and measurements. For glaucoma subjects, the variation among visits and measurements were of the same order but larger than in healthy subjects. It was found that independent group comparisons require inconveniently large sample sizes. Within-subject paired comparisons over time require sample sizes of below 15 subjects. The estimated variations for glaucoma subjects imply that 54 months of follow-up is required for detection of change from baseline.

CONCLUSIONS

The variance for subjects is substantial in relation to those for visits and measurements. Cross-sectional independent group comparisons of levels of NRA are unsuitable, due to considerable subject variation. Levels of NRA differences within subjects between visits can be estimated with acceptable precision. Neuro-retinal rim area (NRA) measurement can be used for long-term follow-up of glaucoma progression.

What rates of glaucoma progression are clinically significant?

Clinically important rates of glaucoma progression (worsening) are ones that put a patient at risk of future functional impairment or reduction of vision-related quality of life. Rates of progression can be evaluated through measuring structural or functional changes of the optic nerve. Most treated eyes do not progress at rates that will lead to future visual impairment, but there are a significant proportion (3-17%) of eyes, that are at risk of impairment even under clinical care. While very fast rates of progression (e.g. MD progression of -1.5 dB/year) are generally problematic, much slower rates also may be deleterious for young patients, particularly those diagnosed with late disease. As a result, it is important to consider life expectancy, disease severity and vision-related quality of life based treatment targets to estimate future prognosis when evaluating whether a rate of glaucoma progression can be clinically relevant.

Neuroretinal Rim Area Change in Glaucoma Patients With Visual Field Progression Endpoints and Intraocular Pressure Reduction. The Canadian Glaucoma Study: 4

PURPOSE

To compare rim area rates in patients with and without the visual field (VF) progression endpoint in the Canadian Glaucoma Study and determine whether intraocular pressure (IOP) reduction following the endpoint altered rim area rate.

DESIGN

Prospective multicenter cohort study.

METHODS

setting: University hospitals.

PATIENT POPULATION

Two hundred and six patients with open-angle glaucoma were examined at 4-month intervals with standard automated perimetry and confocal scanning laser tomography.

INTERVENTION

After the endpoint, IOP was reduced by ≥20%.

OUTCOME MEASURES

Univariate analysis for change in rim area rate and multivariable analysis to adjust for independent covariates (eg, age, sex, and IOP).

RESULTS

Patients with an endpoint (n = 59) had a worse rim area rate prior to the endpoint compared to those without (n = 147; median [interquartile range]: -14 [-32, 11] × 10(-3) mm(2)/y and -5 [-14, 5] × 10(-3) mm(2)/y, respectively, P = .02). In univariate analysis, there was no difference in rim area rate before and after the endpoint (median difference [95% CI], 8 (-10, 24) × 10(-3) mm(2)/y), but the muItivariate analysis showed that IOP reduction >2 mm Hg after the endpoint was strongly linked to a reduction in rim area rate decline (8 × 10(-3) mm(2)/y for each additional 1 mm Hg reduction).

CONCLUSIONS

Patients with a VF endpoint had a median rim area rate that was nearly 3 times worse than those without an endpoint. Lower mean follow-up IOP was independently associated with a slower decline in rim area.

The Impact of Location of Progressive Visual Field Loss on Longitudinal Changes in Quality of Life of Patients with Glaucoma

PURPOSE

To evaluate the association between rates of progressive loss in different regions of the visual field and longitudinal changes in quality of life (QoL).

DESIGN

Prospective, observational cohort study.

PARTICIPANTS

The study included 236 patients with glaucomatous visual field loss followed for an average of 4.3±1.5 years.

METHODS

All subjects had the 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) performed annually and standard automated perimetry (SAP) at 6-month intervals. Subjects were included if they had a minimum of 2 NEI VFQ-25 and 5 SAP tests during follow-up. Evaluation of rates of visual field change was performed using 4 different regions (central inferior, central superior, peripheral inferior, and peripheral superior) of the integrated binocular visual field. The association between change in NEI VFQ-25 Rasch-calibrated scores and change in different regions of the visual field was investigated with a joint multivariable longitudinal linear mixed model.

MAIN OUTCOME MEASURES

The relationship between change in QoL scores and change of mean sensitivity in different regions of the visual field.

RESULTS

There was a significant correlation between change in the NEI VFQ-25 Rasch scores during follow-up and change in different regions of the visual field. Each 1 decibel (dB)/year change in binocular mean sensitivity of the central inferior area was associated with a decline of 2.6 units/year in the NEI VFQ-25 scores (R(2) = 35%; P < 0.001). Corresponding associations with change in QoL scores for the peripheral inferior, central superior, and peripheral superior areas of the visual field had R(2) values of 30%, 24%, and 19%, respectively. The association for the central inferior visual field area was statistically significantly stronger than those of the central superior area (P = 0.011) and peripheral superior area (P = 0.001), but not the peripheral inferior area (P = 0.171). Greater declines in NEI VFQ-25 scores were also seen in patients who had worse visual field sensitivity at baseline.

CONCLUSIONS

Progressive decline in sensitivity in the central inferior area of the visual field had the strongest association with longitudinal decline in QoL of patients with glaucoma.

How to detect progression in glaucoma

Detecting glaucoma progression remains one of the most challenging aspects of glaucoma management, since it can be hard to distinguish disease progression from exam variability and changes due to aging. In this review article, we discuss the use of perimetry, confocal scanning laser tomography and optical coherence tomography to detect glaucoma progression, and the techniques available to evaluate change with these modalities. Currently, there is no consensus on the best technique or criteria to detect glaucoma progression, or what amount of change would be clinically meaningful. New techniques have been developed to assess glaucoma progression, which make more comprehensive and complex use of data. They have the potential of detecting progression with better accuracy, with shorter follow-up periods, and generating better prognostics. Further validation of these new techniques is still required, but their incorporation into clinical practice is likely to yield significant benefits.

Frequency Doubling Technology Perimetry and Changes in Quality of Life of Glaucoma Patients: A Longitudinal Study

PURPOSE

To evaluate the relationship between rates of change on frequency doubling technology (FDT) perimetry and longitudinal changes in quality of life (QoL) of glaucoma patients.

DESIGN

Prospective observational cohort study.

METHODS

One hundred fifty-two subjects (127 glaucoma and 25 healthy) were followed for an average of 3.2 ± 1.1 years. All subjects were evaluated with National Eye Institute Visual Function Questionnaire (NEI VFQ-25), FDT, and standard automated perimetry (SAP). Glaucoma patients had a median of 3 NEI VFQ-25, 8 FDT, and 8 SAP tests during follow-up. Mean sensitivities of the integrated binocular visual fields were estimated for FDT and SAP and used to calculate rates of change. A joint longitudinal multivariable mixed model was used to investigate the association between change in binocular mean sensitivities and change in NEI VFQ-25 Rasch-calibrated scores.

RESULTS

There was a statistically significant correlation between change in binocular mean sensitivity for FDT and change in NEI VFQ-25 scores during follow-up in the glaucoma group. In multivariable analysis with the confounding factors, each 1 dB/year change in binocular FDT mean sensitivity corresponded to a change of 0.8 units per year in the NEI VFQ-25 scores (P = .001). For binocular SAP mean sensitivity, each 1 dB/year change was associated with 2.4 units per year change in NEI VFQ-25 scores (P < .001). The multivariable model containing baseline and rate of change information from SAP had stronger ability to predict change in NEI VFQ-25 scores compared to the equivalent model for FDT (R(2) of 50% and 30%, respectively; P = .001).

CONCLUSION

SAP performed significantly better than FDT in predicting change in NEI VFQ-25 scores in our population, suggesting that it may still be the preferable perimetric technique for predicting risk of disability from the disease.

Association between progressive retinal nerve fiber layer loss and longitudinal change in quality of life in glaucoma

IMPORTANCE

Evaluation of structural optic nerve damage is a fundamental part of diagnosis and management of glaucoma. However, the relationship between structural measurements and disability associated with the disease is not well characterized. Quantification of this relationship may help validate structural measurements as markers directly relevant to quality of life.

OBJECTIVE

To evaluate the relationship between rates of retinal nerve fiber layer (RNFL) loss and longitudinal changes in quality of life in glaucoma.

DESIGN, SETTING, AND PARTICIPANTS

Observational cohort study including 260 eyes of 130 patients with glaucoma followed up for a mean (SD) of 3.5 (0.7) years. All patients had repeatable visual field defects on standard automated perimetry (SAP) at baseline. The 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was performed annually, and spectral-domain optical coherence tomography and SAP were performed at 6-month intervals. A joint model was used to investigate the association between change in NEI VFQ-25 Rasch-calibrated scores and change in RNFL thickness, adjusting for confounding socioeconomic and clinical variables.

MAIN OUTCOMES AND MEASURES

Association between change in binocular RNFL thickness (RNFL thickness in the better eye at each point) and change in NEI VFQ-25 scores.

RESULTS

Progressive binocular RNFL thickness loss was associated with worsening of NEI VFQ-25 scores over time. In a multivariable model adjusting for baseline disease severity and the rate of change in binocular SAP sensitivity, each 1-μm-per-year loss of RNFL thickness was associated with a decrease of 1.3 units (95% CI, 1.02-1.56) per year in NEI VFQ-25 scores (P < .001). After adjusting for the contribution from SAP, 26% (95% CI, 12%-39%) of the variability of change in NEI VFQ-25 scores was associated uniquely with change in binocular RNFL thickness. The P value remained less than .001 after adjusting for potential confounding factors.

CONCLUSIONS AND RELEVANCE

Progressive binocular RNFL thickness loss was associated with longitudinal loss in quality of life, even after adjustment for progressive visual field loss. These findings suggest that rates of binocular RNFL change are valid markers for the degree of neural loss in glaucoma with significant relationship to glaucoma-associated disability.

Measuring rates of structural and functional change in glaucoma

Glaucoma is a progressive optic neuropathy. Hence, most glaucomatous eyes demonstrate signs of deterioration over time despite what may appear to be adequate treatment. The main goal of glaucoma treatment is to slow the rate of disease so that patients can prolong their functional vision. Therefore, it is important for clinicians caring for patients with glaucoma to be able to estimate rates of change with structural and functional outcomes in their patients. Various trend analysis models have been previously used to estimate rates of decay in glaucoma. The authors discuss the relevant issues and the inherent caveats related to estimating structural and functional rates of change in glaucoma. Patterns of deterioration, testing frequency, and combing structural and functional rates of change are also addressed.

Agreement in identification of glaucomatous progression between the optic disc photography and Heidelberg retina tomography in young glaucomatous patients

AIM

To evaluate concordance between the clinical assessment of glaucomatous progression of the optic disc photography and progression identified by Heidelberg Retina Tomograph (HRT) in patients with suspected primary juvenile open angle glaucoma (JOAG).

METHODS

Optic disc photographs and corresponding HRT II series were reviewed. Optic disc changes between first and final photographs were noted as well as progression identified by HRT topographic change analysis (TCA) and rim area regression line (RARL) Agreement between progression indentified by photography and HRT methods was assessed. Progression, determined from optic disc photographs by consensus assessment was used as the reference standard.

RESULTS

A total of 31 patients (59 eyes) with suspected JOAG were studied. Agreement for progression/no progression between TCA and photography was obtained in 4 progressing eyes and 38 stable eyes (71.19%, k=0.11). Agreement for progression/no progression between RARL and photography was detected in 5 progressing eyes and in 34 stable eyes (66.10%, k=0.15). The number of HRT per patient was statistically higher in the progressing group (P=0.034).

CONCLUSION

Agreement for detection of longitudinal changes between photography and HRT analysis was poor. One way to improve the chance of discovery of the progression could be increasing the number of HRT examinations.

Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images

Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM).

A novel optic nerve photograph alignment and subtraction technique for the detection of structural progression in glaucoma

PURPOSE

To highlight changing features over time within a single static image through the auto-alignment and subtraction of serial optic nerve photographs.

METHODS

Subtraction maps were generated from auto-aligned (EyeIC, Narbeth, PA) baseline and follow-up images using Adobe Photoshop software. They demonstrated progressive retinal nerve fibre layer (RNFL) defects, optic disc haemorrhage (DH), neuroretinal rim loss (RL) and peripapillary atrophy (PPA). A masked glaucoma specialist identified features of progression on subtraction map first, then assessed feature strength by comparison with original images using alternation flicker. Control images with no progression and parallax-only images (as determined by flicker) were included.

RESULTS

Eighty eyes of 67 patients were used to generate subtraction maps that detected glaucoma progression in 87% of DH (n = 28, sensitivity (Se) 82%, specificity (Sp) 98%) and 84% of PPA (n = 30, Se 80%, Sp 98%) cases. The lowest rate of detection was seen with RL at 67% (n = 31, Se 65%, Sp 100%). The subtraction technique was most sensitive for detecting parallax (n = 39, Se 98%, Sp 94%). Features of glaucoma progression appeared equally strong in flicker and subtraction images, but parallax was often enhanced on subtraction maps. Among control images selected for absence of features of glaucomatous change (n = 9) in original flicker images, no features were detected on subtraction maps.

CONCLUSIONS

Auto-alignment and subtraction of serial optic nerve photographs reliably detects features of glaucoma progression with a single static image. Parallax identification may also be facilitated. Auto-alignment and subtraction of serial optic nerve photographs may prove especially useful in education and printed publications when dynamic imaging is not feasible.

[Structural diagnostics of course observation for glaucoma]

BACKGROUND

Imaging of the structural progression of glaucoma enables measurement of the neuroretinal rim of the optic disc, retinal nerve fibre layer and thickness of the ganglion layer.

METHODS

High resolution disc photography, laser scanning tomography, scanning laser polarimetry and optical coherence tomography (OCT) are the current methods of choice to document and measure progression of this chronic degenerative disease.

RESULTS

Loss of the neuroretinal rim is only a few mm(2) or mm(3) per year and has to be differentiated from age-related loss which shows less change over the years. The most pronounced loss is temporal both superior and inferior. Thinning of the retinal nerve fibre layer follows the same pattern with significant annual changes of only 6-7 µm. Modern OCT devices deliver measurements of the macula ganglion cell complex which can be even more sensitive than the thickness of the retinal nerve fibre layer. Qualitative criteria for structural progression are papillary hemorrhage, rarification of papillary vessels and specific changes of the retinal pigment epithelium.

CONCLUSIONS

Structural loss due to glaucoma can be imaged and measured with different methods in different tissues. The evaluation of significant changes is still the responsibility of the ophthalmologist by taking all findings into account.

Rates of retinal nerve fiber layer thinning in glaucoma suspect eyes

PURPOSE

To compare the rates of retinal nerve fiber layer (RNFL) loss in patients suspected of having glaucoma who developed visual field damage (VFD) with those who did not develop VFD and to determine whether the rate of RNFL loss can be used to predict the development of VFD.

DESIGN

Prospective, observational cohort study.

PARTICIPANTS

Glaucoma suspects, defined as having glaucomatous optic neuropathy or ocular hypertension (intraocular pressure, >21 mmHg) without repeatable VFD at baseline, from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study.

METHODS

Global and quadrant RNFL thickness (RNFLT) were measured with the Spectralis spectral-domain optical coherence tomography (SD-OCT; Spectralis HRA+OCT [Heidelberg Engineering, Heidelberg, Germany]). Visual field damage was defined as having 3 consecutive abnormal visual fields. The rate of RNFL loss in eyes developing VFD was compared to eyes not developing VFD using multivariate linear mixed-effects models. A joint longitudinal survival model used the estimated RNFLT slope to predict the risk of developing VFD, while adjusting for potential confounding variables.

MAIN OUTCOME MEASURES

The rate of RNFL thinning and the probability of developing VFD.

RESULTS

Four hundred fifty-four eyes of 294 glaucoma suspects were included. The average number of SD-OCT examinations was 4.6 (range, 2-9), with median follow-up of 2.2 years (0.4-4.1 years). Forty eyes (8.8%) developed VFD. The estimated mean rate of global RNFL loss was significantly faster in eyes that developed VFD compared with eyes that did not develop VFD (-2.02 μm/year vs. -0.82 μm/year; P<0.001). The joint longitudinal survival model showed that each 1-μm/year faster rate of global RNFL loss corresponded to a 2.05-times higher risk of developing VFD (hazard ratio, 2.05; 95% confidence interval, 1.14-3.71; P = 0.017).

CONCLUSIONS

The rate of global RNFL loss was more than twice as fast in eyes that developed VFD compared with eyes that did not develop VFD. A joint longitudinal survival model showed that a 1-μm/year faster rate of RNFLT loss corresponded to a 2.05-times higher risk of developing VFD. These results suggest that measuring the rate of SD-OCT RNFL loss may be a useful tool to help identify patients who are at a high risk of developing visual field loss.

Scanning laser polarimetry in glaucoma

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Comparison of Heidelberg retina tomography, optical coherence tomography and Humphrey visual field in early glaucoma diagnosis

OBJECTIVE

To determine the value of optic disc parameters and perimetric defects in the early diagnosis of patients with primary open-angle glaucoma (POAG).

METHODS

Optic disc parameters and perimetry were compared among patients in the early stage of POAG, patients with suspected POAG and healthy control subjects, using Heidelberg retina tomography (HRT-II), optical coherence tomography (OCT) and a Humphrey 750i automatic field analyser, in order to determine whether these parameters could be used for early POAG diagnosis.

RESULTS

A total of 55 participants were enrolled in the study. Significant differences in the optic disc parameter and perimetry values were observed between the three groups. HRT-II parameters showed good correlation with OCT parameters. The majority of the HRT-II and OCT parameters showed a good correlation with perimetry values.

CONCLUSIONS

HRT-II and OCT optic disc parameters both reflect morphological changes of the optic disc. These current findings suggest that they can both detect glaucomatous optic neuropathy earlier than a white-on-white perimetry examination. In addition, OCT can detect optic disc parameter changes that cannot be detected by HRT-II.

Adaptive optics retinal imaging--clinical opportunities and challenges

The array of therapeutic options available to clinicians for treating retinal disease is expanding. With these advances comes the need for better understanding of the etiology of these diseases on a cellular level as well as improved non-invasive tools for identifying the best candidates for given therapies and monitoring the efficacy of those therapies. While spectral domain optical coherence tomography offers a widely available tool for clinicians to assay the living retina, it suffers from poor lateral resolution due to the eye's monochromatic aberrations. Ophthalmic adaptive optics (AO) is a technique to compensate for the eye's aberrations and provide nearly diffraction-limited resolution. The result is the ability to visualize the living retina with cellular resolution. While AO is unquestionably a powerful research tool, many clinicians remain undecided on the clinical potential of AO imaging - putting many at a crossroads with respect to adoption of this technology. This review will briefly summarize the current state of AO retinal imaging, discuss current as well as future clinical applications of AO retinal imaging, and finally provide some discussion of research needs to facilitate more widespread clinical use.

Structure-function relationship and diagnostic value of RNFL Area Index compared with circumpapillary RNFL thickness by spectral-domain OCT

PURPOSE

The purpose of the study was to evaluate the structure-function relationship and diagnostic value of retinal nerve fiber layer (RNFL) Area Index from the RNFL thickness deviation map of Cirrus SD-OCT.

METHODS

: A total of 84 normal control eyes, 88 preperimetric eyes, and 146 perimetric glaucoma eyes were analyzed. The area of the RNFL defect in the RNFL thickness deviation map was expressed as RNFL Area Index: 1-[area of superpixels coded in red/(6×6-optic disc area)]. The diagnostic performance of RNFL Area Index and that of circumpapillary RNFL thickness were compared with the area under the receiver operating characteristic curve. Regression analysis was performed with the OCT measurements and the mean retinal sensitivity of the corresponding fields.

RESULTS

: The RNFL Area Index was 96.63±14.22%, 89.89±14.54%, and 81.65±17.11% in the control, preperimetric, and perimetric glaucoma group. The RNFL Area Index had the largest area under the receiver operating characteristic curve to discriminate preperimetric and perimetric glaucoma from normal eyes. The RNFL Area Index showed a strong correlation with circumpapillary RNFL thicknesses in perimetric glaucoma, however, only modest correlation was shown in preperimetric glaucoma. In preperimetric glaucoma, the RNFL Area Index had the strongest associations with mean retinal sensitivity and it was significantly different from those of circumpapillary RNFL thicknesses.

CONCLUSIONS

: The RNFL Area Index showed better diagnostic performance for glaucoma detection and stronger structure-function relationships in preperimetric glaucoma. The RNFL thickness deviation map of Cirrus SD-OCT may be useful to correlate with functional loss in early glaucomatous eyes.

The rate of structural change: the confocal scanning laser ophthalmoscopy ancillary study to the ocular hypertension treatment study

PURPOSE

To compare rates of topographic change in ocular hypertensive eyes that develop primary open-angle glaucoma (POAG) compared to eyes that do not, and to identify factors that influence the rate of change.

DESIGN

Longitudinal, randomized clinical trial.

METHODS

Four hundred forty-one participants (832 eyes) in the Confocal Scanning Laser Ophthalmoscopy Ancillary Study to the Ocular Hypertension Treatment Study were included. POAG was defined as repeatable visual field, photography-based optic disc changes, or both. The rate of topographic change in the 52 participants (66 eyes) who developed POAG was compared with that of participants who did not develop POAG using multivariable mixed effects models.

RESULTS

In both univariate and multivariate analyses, the rate of rim area loss was significantly faster in eyes in which POAG developed than in eyes in which it did not (univariate mean, -0.0131 mm(2)/year and -0.0026 mm(2)/year, respectively). The significantly faster rate of rim area loss in black persons found in the univariate analysis did not remain significant when baseline disc area was included in the model. In multivariate analyses, the rate of rim area loss and other topographic parameters also was significantly faster in eyes with worse baseline visual field pattern standard deviation and higher intraocular pressure during follow-up. Moreover, a significant rate of rim area loss was detected in eyes in which POAG did not develop (P < .0001). The rate of rim area loss in eyes with an optic disc POAG endpoint was significantly faster than in those with a visual field POAG endpoint.

CONCLUSIONS

The rate of rim area loss is approximately 5 times faster in eyes in which POAG developed compared with eyes in which it did not. These results suggest that measuring the rate of structural change can provide important information for the clinical management of ocular hypertensive patients. Additional follow-up is needed to determine whether the statistically significant change in the eyes in which POAG did not develop represents normal aging or glaucomatous change not detected by conventional methods.

Symmetry of optic nerve head parameters measured by the heidelberg retina tomograph 3 in healthy eyes: the Blue Mountains Eye study

PURPOSE

To assess the symmetry of optic nerve head parameters measured by the Heidelberg Retina Tomograph 3 (HRT 3) between fellow eyes in a normal elderly population.

DESIGN

Cross-sectional population-based study.

METHODS

Participants of the Blue Mountains Eye Study 10-year follow-up who did not have optic disc disease, including glaucoma, were included. Optic nerve head parameters measured by HRT 3 were compared between fellow eyes. The normal range of interocular asymmetry (larger disc minus smaller disc) was determined by the 2.5th and 97.5th percentiles.

RESULTS

A total of 1276 eligible participants had HRT scans of both eyes. HRT measurements in right eyes differed slightly in rim steepness and rim volume from those in left eyes (P < .05). The 2.5th and 97.5th percentile of interocular asymmetry limits were -0.41 and 0.45 for cup-to-disc ratio and -0.19 and 0.22 for cup-to-disc area ratio, respectively. The highest interocular correlation was found in disc area and cup area (r ranged from 0.74-0.76), whereas mean cup depth, cup volume, and retinal nerve fiber layer thickness had the poorest correlation (r ≤ 0.07). Greater optic disc area asymmetry was associated with a larger interocular difference in the other optic nerve head parameters.

CONCLUSIONS

There was minimal interocular difference and substantial interocular correlation in optic nerve head parameters measured by HRT 3. Interocular asymmetry greater than 0.2 for cup-to-disc area ratio was considered outside the normal range.

Comparison of long-term variability of retinal nerve fiber layer measurements made with the RTVue OCT and scanning laser polarimetry

Purpose. To compare long-term variability of retinal nerve fiber layer thickness (RNFLT) measurements made with the RTVue-100 Fourier-domain optical coherence tomograph (RTVue-OCT) and scanning laser polarimetry with variable (GDx-VCC) and enhanced (GDx-ECC) corneal compensation. Methods. One eye each of 110 Caucasian patients (17 healthy, 20 ocular hypertensive, 22 preperimetric, and 51 perimetric glaucoma eyes, of which 10 showed visual field progression) were imaged prospectively at 6-month intervals for 1.5 to 3 years. Results. Median change of Octopus visual field mean defect was -0.300 dB/y for the controls, -0.120 dB/y for perimetric glaucoma group, and 1.231 dB/y for the 10 functionally progressing perimetric glaucoma eyes. Relative (%) variance of all RNFLT parameters measured with RTVue-OCT was significantly (p<<0.001) smaller than that with both of the GDx methods. Relative RNFLT progression slopes (% change/y) did not differ significantly between the methods. Relative variance of the RNFLT parameters did not differ between the control and perimetric glaucoma group with RTVue-OCT, but for most parameters it was consistently higher for perimetric glaucoma with both GDx methods (p=0.01). Relative RNFLT progression slopes, however, did not separate the control and perimetric glaucoma eyes with either method. Conclusions. Long-term RNFLT measurements are less variable with the RTVue-OCT than with GDx-VCC and GDx-ECC. Long-term measurement variability is higher in perimetric glaucoma than in healthy eyes with both GDx methods, but no similar between-group difference is seen with RTvue-OCT. None of the tested methods separated the rate of progression between healthy and well-controlled perimetric glaucoma eyes in 1.5 to 3 years follow-up.

Adaptive optics technology for high-resolution retinal imaging

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

Test-retest variability in structural parameters measured with glaucoma imaging devices

In addition to classical stereo-disc photography, various glaucoma imaging devices were developed in the last two decades to quantitatively measure and record glaucoma-related structural parameters of the eye. In determining whether or not the glaucomatous damage progressed from baseline and in estimating the number of test results' optimal frequency needed to confirm disease progression, information relating to the test-retest variability of measurement results provided by each imaging device is indispensable. Such information enables the clinician to apply these devices in practice. The test-retest variability of a system is usually estimated using the Bland-Altman analysis and by calculating the coefficient of variation (CV), intraclass correlation coefficient (ICC), and minimum detectable changes (MDC). The reported CV, ICC, and MDC values for glaucoma-related structural parameter measurement results of stereo-disc photographs, confocal scanning laser ophthalmoscopes, scanning laser polarimeters, time-domain optical coherence tomography (OCT), spectral-domain OCT (SD-OCT), anterior-segment OCT, and ultrasound biomicroscope are systematically reviewed in this manuscript, which will enable the clinician to interpret measurement results provided by each glaucoma imaging devices and thus be useful in practice. Although SD-OCT systems may be currently prevailing because of the volume of information provided and the relatively better test-retest variability, these systems need improvement in their test-retest variability measurement capabilities.

Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects

PURPOSE

To examine the rates of retinal nerve fibre layer thickness (RNFLT) change in glaucoma patients and healthy, age-similar control subjects with three techniques: scanning laser polarimetry with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and time-domain optical coherence tomography (OCT).

METHODS

Sixty-one patients and thirty-three controls were examined with each technique and with standard automated perimetry (SAP) every 6 months. Rates of global RNFLT change and SAP mean deviation (MD) change were estimated with linear mixed-effects models.

RESULTS

The median (interquartile range) baseline age was 64.4 (58.2, 71.0) years for patients and 62.4 (56.3, 70.1) years for controls (P=0.56). There was a median of seven examinations over 3.1 years for patients and six examinations in 3.0 years for controls. Baseline visual field MD and RNFLT for all imaging modalities were significantly lower (P<0.01) in patients compared with controls. Rates of RNFLT change were not significantly different between patients and controls (P≥0.19). Mean rates of VCC-measured RNFLT change were -0.18 and -0.37 μm per year in patients and controls, whereas the respective figures for ECC and OCT were -0.13 and -0.31 μm per year, and 0.04 and 0.61 μm per year. Mean rates of MD change were -0.20 and 0.03 dB per year in patients and controls, respectively (P=0.01).

CONCLUSION

Rates of RNFLT change in glaucoma patients were not statistically different from control subjects for any modality. A significantly negative rate of MD change in patients suggests a genuine, continued deterioration in these patients not reflected by RNFLT changes.

Positional independence of optic nerve head and retinal nerve fiber layer thickness measurements with spectral-domain optical coherence tomography

PURPOSE

To evaluate repeatability and positional independence of optic nerve head (ONH) and retinal nerve fiber layer (RNFL) thickness measurements in sitting and supine body positions using portable spectral-domain optical coherence tomography (iVue SD-OCT; Optovue Inc).

DESIGN

Evaluation of diagnostic technology.

METHODS

Sixty eyes of 30 subjects (10 healthy younger adults aged 20-27 years, 10 healthy older adults aged 50-66 years, and 10 glaucoma patients aged 38-82 years) were included prospectively. For each participant, all measurements were taken in a single session. After 5 minutes in the supine position, 5 scans were obtained from both eyes. Following a 5-minute sitting adaptation, 5 scans were then obtained in the sitting position. The same instrument was used for all measurements. Repeatability and correlation between supine and sitting measurements of 4 ONH and 3 RNFL parameters were assessed using intraclass correlation coefficients (ICC), concordance correlation coefficients (ρ), and Bland-Altman plots.

RESULTS

Measurements were highly repeatable within individual eyes, both for ONH (ICC range, 73%-99%) and RNFL (ICC range, 72%-99%) parameters. The correlation between supine and sitting ONH measurements was strong and ranged from ρ = 97%-99% (younger healthy) to ρ = 98%-99% (older healthy) and ρ = 84%-99% (glaucoma). Bland-Altman plots indicated good agreement between sitting and supine readings of ONH and RNFL parameters.

CONCLUSIONS

Repeatability of measurements of ONH and RNFL is high and measurements between sitting and supine are highly correlated. The ability of the iVue SD-OCT to evaluate ONH and RNFL parameters is good to excellent in both body positions.

Assessment of Structural Glaucoma Progression

Purpose

To provide an update on the role of optic nerve head and peripapillary retinal nerve fiber layer imaging in monitoring glaucoma progression.

Methods

Review of literature.

Results

Imaging technologies, such as optical coherence tomography, scanning laser polarimetry, and confocal scanning laser ophthalmoscopy, objectively and quantitatively measure the structural change associated with glaucoma. Rates of retinal nerve fiber layer (RNFL) and rim area loss are significantly faster in progressing compared with nonprogressing subjects. A number of strategies to detect progression have been proposed. The precision of these methods is generally high. However, there is no agreement as to which instrument or parameter is most appropriate for the evaluation of structural progression associated with glaucoma at this moment. The agreement between structural and functional glaucoma progression is generally poor regardless of the strategies used. Structural progression analyses appear to complement visual field progression analyses, detecting a different subset of progressing subjects.

Summary

Imaging devices are promising tools for monitoring patients with glaucoma. Combining structural and functional analyses is useful for accurate monitoring of glaucoma progression.

How to cite this article

Miki A. Assessment of Structural Glaucoma Progression. J Current Glau Prac 2012;6(2):62-67.

Factors predicting the rate of functional progression in early and suspected glaucoma

PURPOSE

Clinical trials in glaucoma have often sought to predict whether a patient will progress or remain stable. This study proposes to combine and support results from earlier studies, forming a model to predict the actual rate of functional change in glaucoma.

METHODS

Data were taken from 259 eyes of 150 participants with early or suspected glaucoma in the ongoing Portland Progression Project. A total of 3854 study visits were available, each consisting of visual acuity, confocal scanning laser ophthalmoscopy (CSLO), and perimetry. The rate of functional change was calculated over each of 1541 series of six consecutive visits. Mixed effects models were formed to predict these rates using baseline perimetric measurements and CSLO parameters, together with IOP, age, and change in visual acuity through the series (to remove any confound from media changes).

RESULTS

Cup volume from CSLO was predictive of subsequent rate of functional change (P = 0.036), together with baseline mean deviation (P < 0.001) and pattern standard deviation (P = 0.097), age (P = 0.013), maximum IOP during the sequence (P = 0.004), and change in acuity during the sequence (P = 0.022). In a similar model, rim area was less predictive of functional change (P = 0.066).

CONCLUSIONS

A larger optic cup and/or a more damaged visual field are predictive of more rapid perimetric sensitivity loss. The structural parameters most closely correlated with current functional status may not be the parameters that are most useful for predicting the future course of a patient's disease. Maximum IOP may be a more important risk factor than mean IOP over the same time period.

Cup size predicts subsequent functional change in early glaucoma

PURPOSE

To identify structural predictors of functional change in patients with early glaucoma or risk factors for development of glaucoma.

METHODS

One hundred twenty-nine participants with either high-risk ocular hypertension, suspected, or early glaucoma were followed for 10 annual visits. Standard Automated Perimetry was performed at each visit, along with Confocal Scanning Laser Ophthalmoscopy (CSLO). Mean deviation (MD) at the same visit and the subsequent rate of change in MD were predicted by linear regression models based on CSLO parameters along with intraocular pressure, central corneal thickness, and treatment status. Models were assessed by comparing the correlations between predicted and observed perimetric results.

RESULTS

The model using rim area predicted MD at the same visit with correlation 0.445. Using cup area, the equivalent correlation was r = 0.411, lower than the model using rim area with p = 0.096. Using cup volume, the correlation was r = 0.436, and the comparison had p = 0.714; using disc area r = 0.396 and p = 0.011. The model using rim area to predict the subsequent rate of change of MD had r = 0.539. Models using cup area (r = 0.631), cup volume (r = 0.649), or disc area (r = 0.602) were significantly better; p = 0.003, p = 0.001, and p = 0.044, respectively.

CONCLUSIONS

Lower rim area, as measured by CSLO, is predictive of worse function when measured on the same date in participants with high-risk ocular hypertension, suspected, and early glaucoma. However, cup area, cup volume, and disc area may all be more predictive of the rate of subsequent functional change. Parameters should be chosen based on the specific purpose intended and questions asked, rather than using the same parameters in all circumstances.

Neuroretinal rim area and body mass index

PURPOSE

To examine associations between neuroretinal rim area, pressure related factors and anthropometric parameters in a population-based setting.

METHODS

The population-based cross-sectional Beijing Eye Study 2006 included 3251 subjects with an age of 45+ years. The participants underwent a detailed ophthalmic examination. Exclusion criteria for our study were high myopia of more than -8 diopters and angle-closure glaucoma.

RESULTS

The study included 2917 subjects with a mean age of 59.8±9.8 years (range: 45-89 years). Mean neuroretinal rim area was 1.97±0.38 mm², mean intraocular pressure 15.6±3.0 mmHg, mean diastolic blood pressure 79.0±5.9 mm Hg, mean systolic blood pressure 133.5±11.1 mmHg, and mean body mass index was 25.5±3.7. In univariate analysis, neuroretinal rim area was significantly associated with optic disc size, open-angle glaucoma, refractive error, age and gender. After adjustment for these parameters in a multivariate analysis, a larger neuroretinal rim area was significantly correlated with a higher body mass index (P<0.001), in addition to be associated with a lower intraocular pressure (P = 0.004), lower mean blood pressure (P = 0.02), and higher ocular perfusion pressure.

CONCLUSIONS

In a general population, neuroretinal rim as equivalent of the optic nerve fibers is related to a higher body mass index, after adjustment for disc area, refractive error, age, gender, open-angle glaucoma, intraocular pressure, blood pressure and ocular perfusion pressure. Since body mass index is associated with cerebrospinal fluid pressure, the latter may be associated with neuroretinal rim area. It may serve as an indirect hint for an association between cerebrospinal fluid pressure and glaucoma.

African descent and glaucoma evaluation study: asymmetry of structural measures in normal participants

PURPOSE

The purpose of the study is to determine the degree of intereye asymmetry of optic disc topography and retinal nerve fiber layer (RNFL) thickness in healthy individuals of African descent (AD) and European descent (ED).

DESIGN

Observational, clinical study.

METHODS

Five hundred nineteen healthy individuals (AD, n=262, mean age=44.9 years; ED, n=257, mean age=47.1 years) from the African Descent and Glaucoma Evaluation Study and Diagnostic Innovations in Glaucoma Study were tested using Heidelberg retina romograph (HRT), GDx variable corneal compensation (GDx-VCC), and standard, automated perimetry within 6 months of one another. HRT-II measurements included cup area, cup volume, rim area, and rim volume. GDx-VCC measurements included average RNFL thickness. Intereye asymmetry was calculated as the absolute value of the differences in measurements between the right and left eye.

RESULTS

AD participants showed significantly higher median asymmetry in cup volume and rim volume (P<0.001 and 0.033, respectively) compared with ED participants. The effect of race lost significance after adjustment for mean disc area and disc area asymmetry in multivariable models. Axial length asymmetry was not correlated with increased asymmetry in any of this study's asymmetry parameters. Normal ranges of asymmetry for the HRT-II measurements of cup area (up to 0.39 mm), cup volume (up to 0.15 mm), rim area (up to 0.45 mm), and rim volume (up to 0.22 mm) were derived, as were asymmetry ranges for GDx-VCC-measured average RNFL thickness (up to 6.25 μm).

CONCLUSIONS

The effect of race was no longer significant after adjustment for mean disc area and disc area asymmetry. Individuals with asymmetries with magnitudes greater than those of the normal ranges could be considered as suspicious for glaucoma.