Detection of optic disc change with the Heidelberg retina tomograph before confirmed visual field change in ocular hypertensives converting to early glaucoma

Differing Associations between Optic Nerve Head Strains and Visual Field Loss in Patients with Normal- and High-Tension Glaucoma

PURPOSE

To study the associations between optic nerve head (ONH) strains under intraocular pressure (IOP) elevation with retinal sensitivity in patients with glaucoma.

DESIGN

Clinic-based cross-sectional study.

PARTICIPANTS

Two hundred twenty-nine patients with primary open-angle glaucoma (subdivided into 115 patients with high-tension glaucoma [HTG] and 114 patients with normal-tension glaucoma [NTG]).

METHODS

For 1 eye of each patient, we imaged the ONH using spectral-domain OCT under the following conditions: (1) primary gaze and (2) primary gaze with acute IOP elevation (to approximately 35 mmHg) achieved through ophthalmodynamometry. A 3-dimensional strain-mapping algorithm was applied to quantify IOP-induced ONH tissue strain (i.e., deformation) in each ONH. Strains in the prelaminar tissue (PLT), the retina, the choroid, the sclera, and the lamina cribrosa (LC) were associated (using linear regression) with measures of retinal sensitivity from the 24-2 Humphrey visual field test (Carl Zeiss Meditec). This was performed globally, then locally according to a previously published regionalization scheme.

MAIN OUTCOME MEASURES

Associations between ONH strains and values of retinal sensitivity from visual field testing.

RESULTS

For patients with HTG, we found (1) significant negative linear associations between ONH strains and retinal sensitivity (P < 0.001; on average, a 1% increase in ONH strains corresponded to a decrease in retinal sensitivity of 1.1 decibels [dB]), (2) that high-strain regions colocalized with anatomically mapped regions of high visual field loss, and (3) that the strongest negative associations were observed in the superior region and in the PLT. In contrast, for patients with NTG, no significant associations between strains and retinal sensitivity were observed except in the superotemporal region of the LC.

CONCLUSIONS

We found significant negative associations between IOP-induced ONH strains and retinal sensitivity in a relatively large glaucoma cohort. Specifically, patients with HTG who experienced higher ONH strains were more likely to exhibit lower retinal sensitivities. Interestingly, this trend in general was less pronounced in patients with NTG, which could suggest a distinct pathophysiologic relationship between the two glaucoma subtypes.

Comparison of Different Machine Learning Classifiers for Glaucoma Diagnosis Based on Spectralis OCT

Early detection is important in glaucoma management. By using optical coherence tomography (OCT), the subtle structural changes caused by glaucoma can be detected. Though OCT provided abundant parameters for comprehensive information, clinicians may be confused once the results conflict. Machine learning classifiers (MLCs) are good tools for considering numerous parameters and generating reliable diagnoses in glaucoma practice. Here we aim to compare different MLCs based on Spectralis OCT parameters, including circumpapillary retinal nerve fiber layer (cRNFL) thickness, Bruch’s membrane opening-minimum rim width (BMO-MRW), Early Treatment Diabetes Retinopathy Study (ETDRS) macular thickness, and posterior pole asymmetry analysis (PPAA), in discriminating normal from glaucomatous eyes. Five MLCs were proposed, namely conditional inference trees (CIT), logistic model tree (LMT), C5.0 decision tree, random forest (RF), and extreme gradient boosting (XGBoost). Logistic regression (LGR) was used as a benchmark for comparison. RF was shown to be the best model. Ganglion cell layer measurements were the most important predictors in early glaucoma detection and cRNFL measurements were more important as the glaucoma severity increased. The global, temporal, inferior, superotemporal, and inferotemporal sites were relatively influential locations among all parameters. Clinicians should cautiously integrate the Spectralis OCT results into the entire clinical picture when diagnosing glaucoma.

A neuroglia-based interpretation of glaucomatous neuroretinal rim thinning in the optic nerve head

Neuroretinal rim thinning (NRR) is a characteristic glaucomatous optic disc change. However, the precise mechanism of the rim thinning has not been completely elucidated. This review focuses on the structural role of the glioarchitecture in the formation of the glaucomatous NRR thinning. The NRR is a glia-framed structure, with honeycomb geometry and mechanically reinforced astrocyte processes along the transverse plane. When neural damage selectively involves the neuron and spares the glia, the gross structure of the tissue is preserved. The disorganization and loss of the glioarchitecture are the two hallmarks of optic nerve head (ONH) remodeling in glaucoma that leads to the thinning of NRR tissue upon axonal loss. This is in contrast to most non-glaucomatous optic neuropathies with optic disc pallor where hypertrophy of the glioarchitecture is associated with the seemingly absent optic disc cupping. Arteritic anterior ischemic optic neuropathy is an exception where pan-necrosis of ONH tissue leads to NRR thinning. Milder ischemia indicates selective neuronal loss that spares glia in non-arteritic anterior ischemic optic neuropathy. The biological reason is the heterogeneous glial response determined by the site, type, and severity of the injury. The neuroglial interpretation explains how the cellular changes underlie the clinical findings. Updated understandings on glial responses illustrate the mechanical, microenvironmental, and microglial modulation of activated astrocytes in glaucoma. Findings relevant to the possible mechanism of the astrocyte death in advanced glaucoma are also emerging. Ultimately, a better understanding of glaucomatous glial response may lead to glia-targeting neuroprotection in the future.

Visible-light optical coherence tomography-based multimodal system for quantitative fundus autofluorescence imaging

IMPACT STATEMENT

Quantitative fundus autofluorescence imaging with simultaneous visible-light optical coherence tomography-based multimodal technology has potential significant impact on the diagnosis and monitoring the progression of retinal diseases.

The Relationship Between Bruch's Membrane Opening-Minimum Rim Width and Retinal Nerve Fiber Layer Thickness and a New Index Using a Neural Network

PURPOSE

We evaluate the relationship between Bruch's membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer thickness (pRNFLT) and develop a new parameter combining BMO-MRW and pRNFLT using a neural network to maximize their compensatory values.

METHODS

A total of 402 subjects were divided into two groups: 273 (validation group) and 129 (neural net training) subjects. Linear quadratic and broken-stick regression models were used to explore the relationship between BMO-MRW and pRNFLT. A multilayer neural network was used to create a combined parameter, and diagnostic performances were compared using area under the receiver operating characteristic curves (AUROCs).

RESULTS

Regression analyses between BMO-MRW and pRNFLT revealed that the broken-stick model afforded the best fit. Globally, the tipping point was a BMO-MRW of 226.5 μm. BMO-MRW and pRNFLT were correlated significantly with visual field. When differentiating normal from glaucoma subjects, the neural network exhibited the largest AUROC. When differentiating normal from early glaucoma subjects, the overall diagnostic performance decreased, but the neural network still exhibited the largest AUROC.

CONCLUSIONS

The optimal relationship between BMO-MRW and pRNFLT was revealed using the broken-stick model. Considerable BMO-MRW thinning preceded pRNFLT thinning. The neural network significantly improved diagnostic power by combining BMO-MRW and pRNFLT.

TRANSLATIONAL RELEVANCE

A combined index featuring BMO-MRW and pRNFLT data can aid clinical decision-making, particularly when individual parameters yield confusing results. Our neural network effectively combines information from separate parameters.

Quadrant Field Pupillometry Detects Melanopsin Dysfunction in Glaucoma Suspects and Early Glaucoma

It is difficult to detect visual function deficits in patients at risk for glaucoma (glaucoma suspects) and at early disease stages with conventional ophthalmic tests such as perimetry. To this end, we introduce a novel quadrant field measure of the melanopsin retinal ganglion cell mediated pupil light response corresponding with typical glaucomatous arcuate visual field defects. The melanopsin-mediated post-illumination pupil response (PIPR) was measured in 46 patients with different stages of glaucoma including glaucoma suspects and compared to a healthy group of 21 participants with no disease. We demonstrate that the superonasal quadrant PIPR differentiated glaucoma suspects and early glaucoma patients from controls with fair (AUC = 0.74) and excellent (AUC = 0.94) diagnostic accuracy, respectively. The superonasal PIPR provides a linear functional correlate of structural retinal nerve fibre thinning in glaucoma suspects and early glaucoma patients. This first report that quadrant PIPR stimulation detects melanopsin dysfunction in patients with early glaucoma and at pre-perimetric stages may have future implications in treatment decisions of glaucoma suspects.

Confocal Laser Scanning Tomography to Predict Visual Field Conversion in Patients With Ocular Hypertension and Early Glaucoma

PURPOSE

To compare Moorfields regression analysis (MRA), Glaucoma probability score (GPS), and different discriminant functions to predict future visual field conversion of patients with ocular hypertension and early glaucoma.

PATIENTS AND METHODS

The study included 120 eyes of patients with ocular hypertension and 110 eyes of patients with early glaucoma from the Erlangen glaucoma registry. Annually, all patients underwent standard automated perimetry, 24-hour intraocular pressure profile, optic disc photography, and HRT (Heidelberg Retina Tomograph I-III; Heidelberg Engineering) measurements. The cohort was divided into 2 groups based on the development of repeatable glaucomatous visual fields. Positive predictive values and negative predictive values were compared for MRA, GPS, and the classification of Bathija, Iester, Mardin, and Mikelberg at baseline. Kaplan-Meier Survival curves and Logrank tests were used to evaluate equality of survival distributions for different test results.

RESULTS

Median follow-up was 9.04 years. 26 eyes (11.3%) demonstrated glaucomatous visual field loss in the follow-up. MRA temporal-superior and temporal-inferior outside normal limits were predictive of future visual field loss with positive predictive values of 33.3% and 28.6%. Normal GPS Temporal Sector demonstrated a negative predictive value of 96.4% and normal results in discriminant functions between 94.7% and 95.5%.

CONCLUSIONS

Confocal scanning laser tomography is a useful imaging modality to predict future visual field conversion. Development of visual field defects in 10 years is highly unlikely, if GPS classification and/or classification of discriminant analysis at baseline are normal. MRA temporal-superior and temporal-inferior outside normal limits are associated with future VF conversion (ClinicalTrials.gov number, NCT00494923).

Summary of Glaucoma Diagnostic Testing Accuracy: An Evidence-Based Meta-Analysis

Background

New glaucoma diagnostic technologies are penetrating clinical care and are changing rapidly. Having a systematic review of these technologies will help clinicians and decision makers and help identify gaps that need to be addressed. This systematic review studied five glaucoma technologies compared to the gold standard of white on white perimetry for glaucoma detection.

Methods

OVID^® interface: MEDLINE^® (In-Process & Other Non-Indexed Citations), EMBASE^®, BIOSIS Previews^®, CINAHL^®, PubMed, and the Cochrane Library were searched. A gray literature search was also performed. A technical expert panel, information specialists, systematic review method experts and biostatisticians were used. A PRISMA flow diagram was created and a random effect meta-analysis was performed.

Results

A total of 2,474 articles were screened. The greatest accuracy was found with frequency doubling technology (FDT) (diagnostic odds ratio (DOR): 57.7) followed by blue on yellow perimetry (DOR: 46.7), optical coherence tomography (OCT) (DOR: 41.8), GDx (DOR: 32.4) and Heidelberg retina tomography (HRT) (DOR: 17.8). Of greatest concern is that tests for heterogeneity were all above 50%, indicating that cutoffs used in these newer technologies were all very varied and not uniform across studies.

Conclusions

Glaucoma content experts need to establish uniform cutoffs for these newer technologies, so that studies that compare these technologies can be interpreted more uniformly. Nevertheless, synthesized data at this time demonstrate that amongst the newest technologies, OCT has the highest glaucoma diagnostic accuracy followed by GDx and then HRT.

Exploring early glaucoma and the visual field test: classification and clustering using Bayesian networks

Bayesian networks (BNs) are probabilistic models used for classification and clustering in several fields. Their ability to deal with unobserved variables and to integrate data and expert knowledge make them an appropriate technique for modeling eye functionality measurements in glaucoma. In this study, a set of BNs is used to simultaneously perform classification of early glaucoma and cluster data into different stages of disease. A novel learning algorithm that combines clustering and quasi-greedy search is also proposed. The classification performances of the models are evaluated on an independent dataset, while the clusters are compared to K-means, previous publications, and direct knowledge. The use of clustering and structure learning enabled the exploration of the visual field patterns of the disease while obtaining good results both on pre- (50% sensitivity at 90% specificity) and post- (85% sensitivity at 90% specificity) diagnosis data. Clusters obtained were insightful and in conformity with consolidated knowledge in the field.

Predictive value of heidelberg retina tomograph parameters for the development of glaucoma in the European glaucoma prevention study

PURPOSE

To determine whether baseline Heidelberg Retina Tomograph (HRT) measurements of the optic disc are associated with the development of open-angle glaucoma (OAG) in individuals with ocular hypertension in the European Glaucoma Prevention Study (EGPS).

DESIGN

Retrospective analysis of a prospective, randomized, multicenter, double-masked, controlled clinical trial.

METHODS

There were 489 participants in the HRT Ancillary Study to the EGPS. Each baseline HRT parameter was assessed in univariate and multivariate proportional hazards models to determine its association with the development of OAG. Proportional hazards models were used to identify HRT variables that predicted which participants in the EGPS had developed OAG. Development of OAG was based on visual field and/or optic disc changes.

RESULTS

At a median follow-up time of about 5 years, 61 participants developed OAG. In multivariate analyses, adjusting for randomization arm, age, baseline IOP, central corneal thickness, pattern standard deviation, and HRT disc area, the following HRT parameters were associated with the development of OAG: the "outside normal limits" classification of the Frederick Mikelberg (FSM) discriminant function (hazard ratio [HR] 2.51, 95% confidence interval [CI]: 1.45-4.35), larger mean cup depth (HR 1.64, 95% CI: 1.21-2.23), cup-to-disc area ratio (HR 1.43, 95% CI: 1.14-1.80), linear cup-to-disc ratio (HR 1.43, 95% CI: 1.13-1.80), cup area (HR 1.33, 95% CI: 1.08-1.64), smaller rim area (HR 1.33, 95% CI: 1.07-1.64), larger cup volume (HR 1.30, 95% CI: 1.05-1.61), smaller rim volume (HR 1.25, 95% CI: 1.01-1.54), larger maximum cup depth (HR 1.18, 95% CI: 1.01-1.36), and cup shape measure (HR 1.18, 95% CI: 1.01-1.36).

CONCLUSIONS

Several baseline HRT parameters, alone or in combination with baseline clinical and demographic factors, were significantly associated with the development of OAG among the EGPS participants.

Confocal scanning laser tomography of the optic nerve head on the patients with Alzheimer's disease compared to glaucoma and control

The purpose of this study was to evaluate optic nerve head (ONH) differences of the patients with Alzheimer's disease (AD) measured by confocal scanning laser tomography [Heidelberg Retina Tomograph (HRT) III] and compare with glaucoma and control subjects. Eighty-four patients were enrolled into the study: 44 eyes of 24 patients with mild to moderate AD (Group 1), 68 eyes of 35 patients with glaucoma (Group 2), and 49 eyes of 25 heathy volunteers as a control (Group 3). A complete ophthalmologic examination as well as a confocal scanning laser ophthalmoscopic assessment with HRT III were performed on all patients. Mean values of the ONH topographic parameters such as rim area (RA), rim volume (RV), height variation contour, linear cup/disc ratio, cup shape measure, and retinal nerve fiber layer (RNFL) were recorded. Mean values of RNFL thickness was 0.23 ± 0.07 in AD, 0.22 ± 0.09 in glaucoma and 0.24 ± 0.07 in the control group (p = 0.323). RA and RV were significantly lower, and linear C/D ratio was significantly higher in the glaucoma group when compared to AD and control (p < 0.05). There was no statistically significant difference between AD and control for the optic disc parameters tested (p > 0.05). We observed a negative correlation of the age with RNFL in all of the groups (p < 0.005). Age was the most important parameter affecting RNFL. Our results suggest that HRT does not demonstrate ONH differences between AD and control group, while it successfully differentiates glaucoma from AD and control cases of older age.

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.

Detecting abnormality in optic nerve head images using a feature extraction analysis

Imaging and evaluation of the optic nerve head (ONH) plays an essential part in the detection and clinical management of glaucoma. The morphological characteristics of ONHs vary greatly from person to person and this variability means it is difficult to quantify them in a standardized way. We developed and evaluated a feature extraction approach using shift-invariant wavelet packet and kernel principal component analysis to quantify the shape features in ONH images acquired by scanning laser ophthalmoscopy (Heidelberg Retina Tomograph [HRT]). The methods were developed and tested on 1996 eyes from three different clinical centers. A shape abnormality score (SAS) was developed from extracted features using a Gaussian process to identify glaucomatous abnormality. SAS can be used as a diagnostic index to quantify the overall likelihood of ONH abnormality. Maps showing areas of likely abnormality within the ONH were also derived. Diagnostic performance of the technique, as estimated by ROC analysis, was significantly better than the classification tools currently used in the HRT software - the technique offers the additional advantage of working with all images and is fully automated.

Features of optic disc progression in patients with ocular hypertension and early glaucoma

PURPOSE

To determine the clinical features of optic disc progression in patients with ocular hypertension and early glaucoma.

PATIENTS

A total of 336 eyes of 168 patients with ocular hypertension or early glaucoma.

METHODS

Two glaucoma specialists independently graded the baseline and most recent optic disc photographs for optic disc progression. Optic disc progression was defined as: new or increased neuroretinal rim thinning (2 or more clock hours), notching (1 clock hour or less of thinning of the neuroretinal rim), excavation (undermining of the neuroretinal rim or disc margin), and nerve fiber layer defect(s). They also determined the location of these changes.

RESULTS

Ninety-two of 336 eyes (27.4%) showed optic disc progression after a median of 6.1 years. Of those with progression, excavation occurred in 89% of eyes; rim thinning occurring in 54%; and notching occurring in 16%. Fifty-six percent (56%) had 2 or more features of progression. The inferotemporal quadrant was the most common location for progression, but more than 1 location of progression occurred in at least 30% of eyes with progression.

CONCLUSIONS

Optic disc progression occurred frequently in this cohort of ocular hypertension and early glaucoma patients. When evaluating the optic disc for glaucomatous progression, eye care providers should pay particular attention to increased excavation and neuroretinal rim thinning-especially in the inferotemporal quadrant.

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.

Glaucoma severity and medication adherence in a county hospital population

OBJECTIVE

To assess the association between disease severity and adherence with glaucoma medications in a county hospital population.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 126 patients diagnosed with glaucoma receiving intraocular pressure (IOP)-lowering medication were recruited from the San Francisco General Hospital Ophthalmology Clinic.

METHODS

Subjects completed an oral questionnaire to assess demographic information, knowledge of glaucoma, and perceptions of glaucoma medication adherence. Glaucoma disease severity was classified according to the American Academy of Ophthalmology's Preferred Practice Pattern guidelines. Medication adherence was measured for each patient by obtaining pharmacy refill data and calculating medication possession ratio (MPR), that is, the ratio of total days' supply of medication during a 365-day period. Adherence was measured retrospectively over the 18-month period before study entry. Subjects with an MPR >80% were considered adherent.

MAIN OUTCOME MEASURE

Medication adherence.

RESULTS

Subjects with mild or moderate glaucoma were more likely to be nonadherent to their prescribed glaucoma medications than those with severe disease (adjusted odds ratio [OR], 1.54; 95% confidence interval [CI], 1.03-2.31; P = 0.04). Age, gender, race, education level, years of glaucoma, number of medications, and glaucoma diagnosis were not found to be statistically significantly associated with adherence.

CONCLUSION

Patients with severe glaucoma were more likely to adhere to their topical IOP-lowering medication regimen than those with milder glaucomatous disease.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Detection of glaucoma progression by population and individual derived variability criteria

PURPOSE

Ocular imaging devices provide quantitative structural information that might improve glaucoma progression detection. This study examined scanning laser polarimetry (SLP) population-derived versus individual-derived cut-off criteria for detecting progression.

METHODS

Forty-eight healthy, glaucoma suspect and glaucoma subjects, providing 76 eyes were used. All subjects had reliable visual field (VF) and SLP scans acquired at the same visits from ≥4 visits. VF progression was defined by guided progression analysis (GPA) and by the VF index. SLP measurements were analysed by fast mode (FM) GPA, compared with the population rate of progression, and extended mode (EM) GPA, compared with the individual variability. The agreement between progression detection methods was measured.

RESULTS

Poor agreement was observed between progression defined by VF and FM and EM. The difference in temporal-superior-nasal-inferior-temporal (TSNIT) average rate of change between VF defined progressors and non-progressors for both FM (p=0.010) and EM (p=0.015) was statistically significant.

CONCLUSIONS

There is poor agreement between VF and SLP progression regardless of the use of population derived or individual variability criteria. The best SLP progression detection method could not be ascertained, therefore, acquiring three SLP scans per visit is recommended.

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.

Predictive value of retrobulbar blood flow velocities in glaucoma suspects

PURPOSE

To determine whether retrobulbar blood flow (RBF) velocities are predictive of conversion to glaucoma.

METHODS

A total of 262 glaucoma suspects were prospectively selected. Participants had normal visual field, increased intraocular pressure, and glaucomatous optic disc appearance at baseline. Topographic analysis of the optic nerve head was performed using a confocal laser scanning ophthalmoscope and the blood flow velocity of retrobulbar vessels was measured by color Doppler imaging. Conversion to glaucoma was assessed according to the changes in the color-coded Moorfields Regression Analysis (MRA) classification of the confocal laser scanning system during a 48-month follow-up period. Survival curves and hazard ratios (HRs) for the association between RBF parameters and conversion to glaucoma were calculated.

RESULTS

End-diastolic velocity and mean velocity in the ophthalmic artery were reduced in subjects that converted to glaucoma based on MRA (36 individuals, 13.7%), while resistivity (RI) and pulsatility indices were increased in the same vessel. Patients with RI values lower than 0.75 in the ophthalmic artery had a survival rate (MRA-converters versus nonconverters) of 93.9%, whereas individuals with RI values greater than 0.75 had a survival rate of 81.7% (HR = 3.306; P = 0.002).

CONCLUSIONS

Abnormal RBF velocities measured by color Doppler ultrasound may be a risk factor for conversion to glaucoma. An RI value higher than 0.75 in the ophthalmic artery was associated with the development of glaucoma.

Digital versus film stereo-photography for assessment of the optic nerve head in glaucoma and glaucoma suspect patients

PURPOSE

One of the leading methods for optic nerve head assessment in glaucoma remains stereoscopic photography. This study compared conventional film and digital stereoscopy in the quantitative and qualitative assessment of the optic nerve head in glaucoma and glaucoma suspect patients.

METHODS

Fifty patients with glaucoma or suspected glaucoma underwent stereoscopic photography of the optic nerve head with a 35-mm color slide film and a digital camera. Photographs/images were presented in random order to 3 glaucoma specialists for independent analysis using a standardized assessment form. Findings for the following parameters were compared among assessors and between techniques: cup/disc (C/D) ratio, state of the optic rim, presence of peripapillary atrophy and appearance of the retinal nerve fiber layer, blood vessels, and lamina cribrosa. The film-based and image-based diagnoses (glaucoma yes/no) were compared as well.

RESULTS

Despite high level of agreement across graders using the same method for the horizontal and vertical C/D ratio, (intraclass correlations 0.80 to 0.83), the agreement across graders was much lower for the other parameters using the same method. Similarly the agreement between the findings of the same grader using either method was high for horizontal and vertical C/D ratio, but low for the other parameters. The latter differences were reflected in the disagreement regarding the final diagnosis: The diagnoses differed by technique for each grader in 18% to 46% of eyes, resulting in 38.5% of eyes diagnosed with glaucoma by film photography that "lost" their diagnosis on the digital images, whereas 18.7% of eyes diagnosed as nonglaucomatous by film photography were considered to have glaucoma on the digital images.

CONCLUSIONS

Although there is consistency between 35-mm film stereoscopy and digital stereoscopy in determining the cup/disc (C/D) ratio, in all other parameters large differences exist, leading to differences in diagnosis. Differences in capturing images between digital and film photography may lead to loss of information and misdiagnosis. Further studies are needed to determine the reliability of the new digital techniques.

Short-term changes in the optic nerve head and visual field after trabeculectomy

AIMS OR PURPOSE: To evaluate short-term changes in optic nerve head topography and visual field induced by surgical reduction of intraocular pressure.

METHODS

A prospective study was performed on 56 eyes of 56 patients with uncontrolled primary open-angle glaucoma despite maximum medical therapy, which underwent trabeculectomy. Optic nerve head evaluations by means of Heidelberg Retina Tomograph, and visual field tests were performed pre-operatively, and at 3 and 6 months after surgery. Differences in intraocular pressure, visual field indices, and Heidelberg Retina Tomograph parameters were evaluated with the t-test for paired data. A linear regression model was calculated to analyze the relationship between intraocular pressure reduction and visual field changes, and optic nerve head changes.

RESULTS

Mean intraocular pressure decreased from 24.4 ± 5.0 mm Hg to 12.1 ± 3.1 mm Hg (month 3, P<0.001), and 10.6 ± 2.8 mm Hg (month 6, P<0.001) after trabeculectomy. Mean retinal nerve fiber layer thickness (baseline, 0.19 ± 0.034; month 3, 0.24 ± 0.039, P=0.05; month 6, 0.21 ± 0.037, P=0.05) showed a statistical significant change compared with baseline values.

CONCLUSIONS

In this 6-months study, a significant increase in retinal nerve fiber layer thickness was detected after glaucoma filtration surgery.

Glaucomatous optic neuropathy evaluation project: a standardized internet system for assessing skills in optic disc examination

BACKGROUND

Development of a standardized internet-based system to self-assess skills in optic disc examination for glaucoma risk assessment.

DESIGN

Prospective internet-based observational study.

PARTICIPANTS

Total of 197 participants (glaucoma subspecialists, general ophthalmologists and trainees) from 22 countries.

METHODS

Forty-two optic disc images demonstrating a range of features were selected from 2500 monoscopic disc photographs of normal and glaucomatous eyes. Images were presented to clinicians via website (http://www.gone-project.com). Participants were asked to assess nine topographic features and make a subjective assessment of glaucoma likelihood.

MAIN OUTCOME MEASURES

Inter-observer agreement using kappa (κ) or weighted kappa (κ(w) ).

RESULTS

There was substantial level of inter-observer agreement between glaucoma subspecialists for assessment of glaucoma likelihood (κ(w) = 0.63). Inter-observer agreement was high for haemorrhage (κ= 0.83) and substantial for disc size, disc shape, cup:disc ratio, peripapillary atrophy and cup shape (κ(w) = 0.59-0.68). Subspecialists had stronger inter-observer agreement for glaucoma likelihood and for most disc characteristics than did trainees: the greatest difference being the assessment for retinal nerve fibre layer loss. Analysis of individual disc answers from ophthalmology trainees showed that discs leading to lower agreement of glaucoma likelihood tend to produce lower agreement for the assessment of cup:disc ratio, cup shape, cup depth and retinal nerve fibre layer. Discs with features of moderate to deep cup or cup:disc ratio between 0.6 and 0.8 also lead to lower agreement in glaucoma likelihood.

CONCLUSIONS

This internet-based system is a readily accessible and standardized tool, for clinicians globally, that permits self-assessment and benchmarking of skills in optic disc examination.

Heidelberg Retina Tomography analysis in optic disks with anatomic particularities

Due to its objectivity, reproducibility and predictive value confirmed by many large-scale statistical clinical studies, Heidelberg Retina Tomography has become one of the most used computerized image analysis of the optic disc in glaucoma. It has been signaled, though, that the diagnostic value of Moorfieds Regression Analyses and Glaucoma Probability Score decreases when analyzing optic discs with extreme sizes. The number of false positive results increases in cases of megalopapillae and the number of false negative results increases in cases of small size optic discs. The present paper is a review of the aspects one should take into account when analyzing a HRT result of an optic disc with anatomic particularities.

Glaucomatous progression in series of stereoscopic photographs and Heidelberg retina tomograph images

OBJECTIVE

To compare optic disc changes using automated analysis of Heidelberg retina tomograph (HRT) images with assessments, by glaucoma specialists, of change in stereoscopic photographs.

METHODS

Baseline and follow-up stereophotographs and corresponding HRT I series of 91 eyes from 56 patients were selected. The selection criteria were sufficiently long, good-quality HRT series (7 visits in > or =70 months of follow-up) and follow-up photographs contemporaneous with the final HRT image. Topographic change analysis (TCA), statistic image mapping (SIM), and linear regression of rim area (RALR) across time were applied to HRT series. Glaucomatous change determined from stereophotographs by expert observers was used as the reference standard.

RESULTS

Expert observers identified 33 eyes (36%) as exhibiting glaucomatous change. Altering HRT progression criteria such that 36% of eyes progressed according to each method resulted in concordance between HRT methods and stereophotograph assessment of 54% for TCA, 65% for SIM, and 67% for RALR (Cohen kappa = 0.05, 0.23, and 0.30, respectively). Receiver operating characteristic curves of the HRT analyses revealed poor precision of HRT analyses to predict stereophotograph-assessed change: areas under the curve were 0.61 for TCA, 0.62 for SIM, and 0.66 for RALR.

CONCLUSIONS

Statistical methods for detecting structural changes in HRT images exhibit only moderate agreement with each other and have poor agreement with expert-assessed change in optic disc stereophotographs.

Optic disc damage staging system

PURPOSE

To evaluate the optic disc damage staging system (ODDSS); a new clinical method of optic disc (OD) classification based on OD size, neural rim (NR) loss severity and localization. Accuracy, reproducibility, and reliability were studied. Agreement of ODDSS with the Heidelberg-Retina-Tomograph (HRT) results was evaluated.

METHODS

One eye of 68 consecutive open-angle glaucoma (POAG) patients and 40 controls underwent standard automated perimetry (SAP), HRT-II, and OD examination using the ODDSS classification by 3 independent graders in this prospective cross-sectional study. Sensitivity, specificity, and area under the receiver operating characteristic curve (AROC) in discriminating between normal and POAG eyes were determined for ODDSS and HRT parameters. ODDSS intraobserver and interobserver agreement and agreement with HRT-Moorfield-Regression-Analysis (MRA) were assessed.

RESULTS

ODDSS sensitivity ranged from 72.0% to 89.7%; specificity ranged from 92.5% to 100%. Differences between AROCs for ODDSS (0.89 to 0.94) and for the best-performing HRT parameter (Vertical Cup/Disc Ratio 0.88) were not statistically significant. ODDSS interobserver agreement ranged from 0.33 to 0.78; intraobserver agreement ranged from 0.53 to 0.89. Agreement with HRT-MRA ranged from 0.50 to 0.87.

CONCLUSIONS

ODDSS is a new method for assessing, recording, and sharing information about the clinical OD appearance. Our preliminary results show that it provides good sensitivity and specificity in glaucoma detection. The interobserver and intraobserver agreement ranged from fair to good.

The Heidelberg retina tomograph Glaucoma Probability Score: reproducibility and measurement of progression

PURPOSE

To evaluate the reproducibility of the Heidelberg retina tomograph (HRT) Glaucoma Probability Score (GPS) and assess its potential for monitoring progression.

DESIGN

Evaluation of diagnostic tests in a randomized, controlled clinical trial.

PARTICIPANTS

For reproducibility, we included 43 ocular hypertensive (OHT) and 31 glaucoma subjects. For progression, we included 198 OHT and 21 control subjects.

METHODS

To study reproducibility, global GPS values were generated for HRT images acquired in a test-retest study. Images were acquired at 2 visits within 6 weeks of each other, by 2 different observers. To study progression, GPS values were generated for HRT images acquired prospectively (1993-2001). Linear regression of GPS against time was performed, with progression defined as a significant negative slope (P<0.05). Criterion specificity was estimated from the number of improving subjects (significant positive slope) and the number of progressing controls. Visual field (VF) progression in the same subjects was assessed using 3-omitting pointwise linear regression of sensitivity over time.

MAIN OUTCOME MEASURES

Reproducibility of GPS was assessed using Bland-Altman analysis (mean difference, 95% limits of agreement). Progression was assessed by the number of OHT subjects identified as progressing, and by agreement with VF progression.

RESULTS

Reproducibility of GPS was better at its extremes (-0.01+/-0.20 for GPS 0-0.30, and 0.02+/-0.09 for GPS 0.78-1.00) than in its mid range (0.07+/-0.54 for GPS 0.30-0.78). Estimated criterion specificity ranged from 95.2% (95% confidence interval, 76.1%-99.9%) to 96.8% (93.2%-98.5%). Twenty-five OHT subjects (12.6%) progressed by GPS, with 11 of the 25 (5.6%) also progressing by VF; 26 subjects (13.1%) progressed by VF alone.

CONCLUSIONS

Changes in HRT GPS values between 0.30 and 0.78 should be interpreted with caution because the index has poorer reproducibility in this range. The global GPS progression algorithm performs at least as well as previously described rim area-based HRT progression strategies.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Evaluating the Optic Disc and Retinal Nerve Fiber Layer in Glaucoma II: Optical Image Analysis

Glaucoma is a widespread, blindness-causing disease that is characterized in part by specific and sometimes subtle changes in optic disc and retinal nerve fiber layer topography. Several recently developed computer-based optical imaging techniques allow objective evaluation of the optic disc and retinal nerve fiber layer. These techniques use different optical properties and different properties of the retina to provide micron scale measurements of many aspects of optic disc and retinal nerve fiber layer structure. This article describes and evaluates 3 of these techniques: confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography.

[Contribution and significance of Heidelberg Retinal Tomography II in diagnostics of ocular hypertension and its conversion into primary open-angle glaucoma]

BACKGROUND/AIM

A term "ocular hypertension" is used when IOP is found to be >21 mmHg on two consecutive occasions, in the absence of detectable glaucomatous damage. The aim of this study was to determine the significance and contribution of Heidelberg Retinal Tomography II (HRT II) results that show very early, subtle changes in retinal neurofibre layers (RNFL) in the optic nerve head that are specific for glaucoma itself (the loss of neuroretinal rim area and an increase of Cup/Disc ratio), but are not possible to register by an ophthalmoscope. Also, when the results of the functional tests remain unchanged, that confirms the conversion of ocular hypertension into glaucoma.

METHODS

During a 5-year study period (2002-2007), 29 patients with ocular hypertension were examined. The frequency of control examinations, based on the presence of risk factors for glaucoma development, was 3-6 months. The examination also included IOP measurements with Goldmann Applanation Tonometry (GAT), central corneal thickness (CCT) determination by pachymetry, the examination of chamber angle using indirect gonioscopy, visual field tests by computerized perimetry and also papillae nenr optic (PNO) examination by using HRT II. The application of HRT II enables a great number of stereometric parameters of optic disc, the most important being the rim area and Cup/Disc (C/D) ratio, which was followed during the control examination by each segment, as well as PNO in global.

RESULTS

In the examination period, three cases of conversion of ocular hypertension into a primary open-angle glaucoma were found. In the group of patients with ocular hypertension, HRT II results after six months did not show a significant increase in C/D ratio. No significant loss of rim area or rim volume was found either. In three cases of conversion, HRT II results after 3 months showed an increase of C/D ratio and also a significant loss in rim volume at first examination (0.413) comparing to the last one.

CONCLUSION

In diagnosing ocular hypertension and its conversion to glaucoma, HRT II is used for quantitative evaluation of retinal topography and for quantitative monitoring of topographical changes, especially regarding the increase of C/D ratio and loss of rim volume tissue, which enables to see and register subtle structural changes in optic nerve head and RNFL that are so characteristic for glaucoma, which cannot be seen by an ophthalmoscope. With these results, according to risk factors for glaucoma, one can confirm the diagnosis of ocular hypertension and its conversion to primary open-angle glaucoma. In this study HRT II revealed conversion of ocular hypertension into glaucoma in 10% of the patients.

Performance of confocal scanning laser tomograph Topographic Change Analysis (TCA) for assessing glaucomatous progression

PURPOSE

To determine the sensitivity and specificity of confocal scanning laser ophthalmoscope's Topographic Change Analysis (TCA; Heidelberg Retina Tomograph [HRT]; Heidelberg Engineering, Heidelberg, Germany) parameters for discriminating between progressing glaucomatous and stable healthy eyes.

METHODS

The 0.90, 0.95, and 0.99 specificity cutoffs for various (n=70) TCA parameters were developed by using 1000 permuted topographic series derived from HRT images of 18 healthy eyes from Moorfields Eye Hospital, imaged at least four times. The cutoffs were then applied to topographic series from 36 eyes with known glaucomatous progression (by optic disc stereophotograph assessment and/or standard automated perimetry guided progression analysis, [GPA]) and 21 healthy eyes from the University of California, San Diego (UCSD) Diagnostic Innovations in Glaucoma Study (DIGS), all imaged at least four times, to determine TCA sensitivity and specificity. Cutoffs also were applied to 210 DIGS patients' eyes imaged at least four times with no evidence of progression (nonprogressed) by stereophotography or GPA.

RESULTS

The TCA parameter providing the best sensitivity/specificity tradeoff using the 0.90, 0.95, and 0.99 cutoffs was the largest clustered superpixel area within the optic disc margin (CAREA(disc) mm(2)). Sensitivities/specificities for classifying progressing (by stereophotography and/or GPA) and healthy eyes were 0.778/0.809, 0.639/0.857, and 0.611/1.00, respectively. In nonprogressing eyes, specificities were 0.464, 0.570, and 0.647 (i.e., lower than in the healthy eyes). In addition, TCA parameter measurements of nonprogressing eyes were similar to those of progressing eyes.

CONCLUSIONS

TCA parameters can discriminate between progressing and longitudinally observed healthy eyes. Low specificity in apparently nonprogressing patients' eyes suggests early progression detection using TCA.

Retrobulbar diameter of optic nerve in glaucoma

Introduction. The ultrasound diagnostics of the optic nerve includes the analysis of the optic nerve disc (PNO) and measuring of its retrobulbar diameter. With B-scan, by Schraeder's method, it is possible to measure very precisely the optic nerve, the pial diameter, the normal values for the pial diameter being 2.8-4.1 mm. In glaucoma, the disease that is most frequently associated with higher intraocular pressure, there comes the destruction of nerve fibres, which can be visualized as the excavation of the optic nerve disc. Objective. In this paper, we were interested in finding whether in glaucoma, and in what phase of the disease, the optic nerve starts growing thinner. Aware of many forms of this very complex disease, we were interested in knowing if the visualization of excavation on the optic nerve disc is related to diminishing of the pial diameter of the retrobulbar nerve part. Methods. There were treated the patients who had already had the diagnosis of glaucoma and the visualized excavation of the optic disc of various dimensions. Echographically, there was measured the thickness of the retrobulbar part of the optic nerve and the finding compared in relation to the excavation of the optic disc. Results. In all eyes with glaucoma, a normal size of the retrobulbar part of the optic nerve was measured, ranging from 3.01 to 3.91 mm with the median of 3.36 mm. Also, by testing the correlation between the thickness of the optic nerve and the excavation of the PNO, by Pearson test, we found that there was no correlation between these two parameters (r=0.109; p>0.05). Conclusion. In the patients with glaucoma, the retrobulbar part of the optic nerve is not thinner (it has normal values), even not in the cases with a totally excavated optic disc. There is no connection between the size of the PNO excavation and the thickness of the retrobulbar part of the optic nerve.

Correlation of Disc Damage Likelihood Scale, visual field, and Heidelberg Retina Tomograph II in patients with glaucoma

PURPOSE

To correlate the analysis of the optic nerve head (ONH) obtained with Disc Damage Likelihood Scale (DDLS), Heidelberg Retina Tomograph II (HRT II), and visual field (VF) parameters (Aulhorn scale, mean deviation [MD], and pattern standard deviation [PSD]) in patients with glaucoma.

METHODS

Sixty-five eyes were evaluated using the DDLS classification. Fifty-seven eyes had stable primary open-angle glaucoma (POAG) and eight eyes were normal (control group). Classification of the ONH was performed using the HRT II, with Moorfields Regression Analysis (MRA) and Cup Shape Measure (CSM) indexes. The VF was examined by Full Threshold test (30-2) using the Humphrey Field Analyzer (HFA) perimeter and evaluated by three

METHODS

Aulhorn's scale of 0 to 6, and two global indices, MD and PSD.

RESULTS

The amount of ONH damage as estimated by the DDLS correlated well with topographic damage determined by HRT II (r=0.923 with MRA and r=0.807 with CSM) and with visual field loss as measured by the MD (r=-0.792) and PSD (r=0.718) of the HFA and Aulhorn field staging system (r=0.849).

CONCLUSIONS

This study shows that evaluation of the ONH using the DDLS provides information that correlates well with VF and with data obtained from HRT II.

Morpho-functional follow-up of the optic nerve in treated ocular hypertension: disc morphometry and steady-state pattern electroretinogram

PURPOSE

To examine longitudinally optic disc structure and inner retinal function in treated ocular hypertension (OHT).

MATERIALS AND METHODS

A morphometric (Heidelberg Retina Tomograph, HRT) and functional (steady-state pattern electroretinogram, PERG) evaluation of 27 OHT patients treated with topical beta-blockers and/or prostaglandin analogues and prospectively followed over a 24 +/- 6 month period.

RESULTS

Compared with baseline, mean final PERG amplitude tended to increase (p < 0.01), while HRT was stable. Individual PERG amplitude increase was large (>or= 100%) in some patients (5/27), and unexplained by clinical parameters at baseline.

CONCLUSIONS

In treated OHT, functional responses may improve while disc structure remains stable. The findings suggest that OHT-associated inner retinal dysfunction is at least in part reversible with therapeutic intraocular pressure control.

Limitations of the Heidelberg Retina Tomograph

Glaucoma is a progressive optic neuropathy where damages that occur at the optic nerve head and the retinal never fiber layer are associated with changes in the visual field. The Heidelberg Retina Tomograph (Heidelberg Engineering, Carlsbad, CA), a scanning laser ophthalmoscope, performs a three-dimensional topographic analysis of the optic nerve head and the retinal never fiber layer. The Heidelberg Retina Tomograph has been reported to be a reliable and objective method of identifying structural changes prior to the occurrence of visual field defects. In our series of patients, all had significant visual field defects but normal Heidelberg Retina Tomograph results, including rim area and Moorfield regression analysis. It is important to recognize that interpreting the Heidelberg Retina Tomograph results alone may be misleading; however, when combined with careful clinical evaluation of the optic nerve head and the visual field, the Heidelberg Retina Tomograph may provide valuable information in assisting the clinician with the diagnosis and management of glaucoma.

Discriminating between Normal and Glaucoma-Damaged Eyes with the Heidelberg Retina Tomograph 3

PURPOSE

To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on global stereometric parameters obtained using the Heidelberg Retina Tomograph version 3 (HRT3) for discriminating between healthy eyes and eyes with glaucomatous visual field loss.

DESIGN

Cross-sectional study.

PARTICIPANTS

The authors prospectively selected 81 consecutive healthy subjects and 85 consecutive patients with open-angle glaucoma. Another prospective sample of 225 normal eyes and 210 glaucoma eyes was used to evaluate how well the LDF performed in another population.

METHODS

Participants were divided into 2 groups depending on the results of standard automated perimetry and intraocular pressure. All participants underwent imaging of the optic nerve head with the HRT3.

MAIN OUTCOME MEASURES

The LDF was calculated according to the stepwise logistic regression results of global optic nerve head parameters and glaucoma probability score numerical values. The diagnostic accuracy of the LDF and other parameters included in the software of the HRT3 was evaluated in another independent population.

RESULTS

Based on the results of the stepwise binary logistic regression analysis, the function proposed was LDF = 8.23 - 8.00 x contour line modulation temporal superior + 9.41 x cup shape measure - 4.07 x rim area. The areas under the receiver operating characteristic curve were 0.875 for the LDF, 0.845 for the Frederick S. Mikelberg (FSM) discriminant function, and 0.838 for the Reinhard O. W. Burk (RB) discriminant function. There were no significant differences between these values. The LDF and the FSM and RB discriminant functions yielded sensitivities of 74.2%, 70.4%, and 67.6%, respectively, at a fixed specificity of 85%.

CONCLUSIONS

Compared with the HRT-provided parameters, the proposed LDF exhibited higher diagnostic ability than most available analyses. The LDF had a better sensitivity and specificity balance than the FSM and RB discriminant functions, regardless of optic disc size.

Evaluating the effect of the new alignment algorithm for longitudinal series of Heidelberg retina tomography images

PURPOSE

To evaluate the impact of a new image-alignment algorithm on the repeatability of longitudinal measurements obtained from Heidelberg retina tomograph (HRT) images.

METHODS

HRTI and HRTII image series from 124 patients with glaucoma or ocular hypertension were made available from previously reported studies and were reprocessed with the old and new image-alignment algorithms. Improvements afforded by the new alignment algorithm were examined by considering statistically significant improvement in repeatability of specific stereometric parameters (SP), namely rim area (RA), rim volume (RV), cup volume (CV) and cup shape measure (CSM). A further comparison was made by examining reduction in the variability of pixel-by-pixel height measures within image series.

RESULTS

In some HRT image series, the new algorithm automatically corrected obvious misalignment events that occurred with the previous algorithm. However, average improvement in repeatability of the SP in HRTI image series was not statistically significant (P = 0.13) and there was no statistically significant reduction in pixel-by-pixel height measurement variability (P =0.73). In HRTII image series, there was evidence of improvement, on average, in the repeatability of some parameters (RA, P = 0.01; RV, P = 0.02; CSM, P = 0.05), but not in CV (P = 0.22). There was a large reduction in pixel-by-pixel variability in HRTII image series (P < 0.001).

CONCLUSION

There was no evidence to show that the new algorithm improved repeatability, on average, in HRTI images. However, the application of the new algorithm to HRTII image series marginally improved repeatability in stereometric measures and yielded a significant reduction in pixel-by-pixel variability.

False negative results in glaucoma detection with Heidelberg Retina Tomograph II

Purpose

To evaluate the rate of false negative results with the Heidelberg Retina Tomograph (HRT II) in a glaucoma practice.

Design

Cross-sectional study.

Methods

We analyzed the HRTs taken between October 2002 and October 2003 in our glaucoma clinic, and selected the patients who had a good quality image (SD < 40 μ) with a normal Moorfield’s Regression Analysis (MRA). A masked independent observer classified those patients as normal, glaucoma suspect, or glaucomatous on the basis of optic disc stereo photos (ODP) and at least 2 consecutive reliable automated perimetries. The diagnosis of glaucoma was based on a glaucomatous optic disc with a congruent, reproducible visual field defect.

Results

Four hundred and fifty patients who had undergone an HRT examination were analyzed. One hundred and nine patients had an HRT classified as normal on the MRA, and a good quality image. Fifteen of those 109 patients (13.7%) were classified as glaucomatous on the basis of an abnormal ODP with corresponding visual field defect. Seven (6.4%) patients were classified as glaucoma suspect.

Conclusion

Fourteen percent of glaucoma patients with glaucoma remained undetected with the HRT II Moorfield’s regression analysis as a sole means to detect glaucoma.

Diagnostic ability of the Heidelberg Retina Tomograph 3 for glaucoma

PURPOSE

To compare the diagnostic ability of the Heidelberg Retina Tomograph 3 (HRT3) and the Heidelberg Retina Tomograph 2 (HRT2) for discriminating between healthy eyes and eyes with glaucomatous visual field loss.

DESIGN

Retrospective cross-sectional study.

METHODS

Participants were 93 healthy subjects and 90 patients with open-angle glaucoma. All participants underwent imaging of the optic nerve head with the HRT2. Afterward, HRT data also were analyzed using version 3 of the software without modifying the optic disk contour line. The receiver operating characteristic (ROC) curves between normal and glaucomatous subjects were plotted for the global stereometric parameters of both software versions. Moorfields regression analysis (MRA) and glaucoma probability score (GPS) diagnostic abilities also were compared.

RESULTS

The parameters with the largest areas under the ROC curve were the Frederick S. Mikelberg (FSM) discriminant function for the HRT3 (0.948) and the vertical cup-to-disk ratio (0.914) for the HRT2. At a fixed specificity of 95%, the best sensitivity was 74.4% for the Reinhard O.W. Burk (RB) discriminant function of the HRT2 and 83.3% for the FSM discriminant function of the HRT3. The best sensitivity and specificity pairs for the HRT classifications were 85.5% and 76.3%, respectively, for overall MRA2, 84.4% and 83.8%, respectively, for overall MRA3, 93.3% and 58.0%, respectively, for the global color-coded GPS, and 84.4% and 74.1%, respectively, for the global GPS numerical value.

CONCLUSIONS

At 95% fixed specificity, most HRT3 parameters exhibited at least the same sensitivity for glaucoma diagnosis as the analogous parameters for the HRT2. The diagnostic ability overall of MRA3 was similar to that of the previous version. GPS exhibited higher sensitivity and somewhat lower specificity than the MRA.

Retinal nerve fibre layer measurements and optic nerve head analysis in multiple sclerosis patients

PURPOSE

To verify whether scanning laser polarimeter with the new variable corneal compensation algorithm (GDx VCC) and scanning laser ophthalmoscopy (Heidelberg Retina Tomograph (HRT)) allow measuring retinal ganglion cell loss in patients with multiple sclerosis (MS).

PATIENTS AND METHODS

We enrolled 23 MS patients with a history of previous demyelinating monocular optic neuritis. Examination included visual evoked potentials (VEPs), scanning laser ophthalmoscopy, and scanning laser polarimeter. HRT was performed to assess optic nerve head (ONH) shape, while GDx VCC was used to evaluate the retinal nerve fibre layer thickness (RNFLt) around the ONH. Statistical analysis was performed comparing results obtained for each eye with the available normative database and with the unaffected fellow eye.

RESULTS

When the affected eye group was compared to the fellow-eye group, a significant (P<0.05) difference was found for few GDx VCC parameters. In contrast, no significant correlation was observed between clinical assessment and imaging techniques when the normal database of HRT and GDx VCC was used. A significant association was observed between VEP latency and some GDx VCC parameters.

CONCLUSIONS

Our results suggested that scanning laser polarimetry could detect loss of ganglion cells following demyelinating optic neuritis, but further studies are needed.

Quantification of neuroretinal rim loss using digital planimetry in long-term follow-up of normals and patients with ocular hypertension

PURPOSE

The purpose of this study was to investigate if digital planimetry is appropriate for quantification of neuroretinal rim loss in patients with ocular hypertension (OHT) and if there is an age-related neuroretinal rim loss in normals.

PATIENTS AND METHODS

Fifty-six patients with OHT without optic disc change, 13 patients with OHT and conversion to early glaucoma during follow-up and 42 age-matched controls were recruited from the Erlangen Glaucoma Registry. Annually, all patients underwent complete ophthalmologic examination including detailed diagnostic testing concerning glaucoma. Gold standard for morphologic evaluation of the optic nerve head was the semiquantitative 2-dimensional-method described by Jonas. Optic disc images from baseline and after 5 or 10 years follow-up were used for digital planimetry. Optic disc area and cup area were measured using commercial software: Soft Imaging System analysis. The investigator was masked for diagnosis and time point of examination.

RESULTS

Mean neuroretinal rim loss was 0.36% per year in controls, 0.54% per year in patients with OHT without progressive disease, and 0.95% per year in OHT and conversion.

CONCLUSIONS

Neuroretinal rim loss was highest in the group of OHT with conversion to early glaucoma during follow-up. In the control group we detected a very low mean neuroretinal rim loss during 10-year follow-up. In ocular hypertensive patients without progressive disease mean neuroretinal rim loss was approximately twice compared with normals.

Monitoring glaucomatous progression using a novel Heidelberg Retina Tomograph event analysis

PURPOSE

To describe an event analysis (EA) for monitoring Heidelberg Retina Tomograph (HRT) progression and to establish specificity, detection rate, and agreement with visual field progression by application to longitudinal data.

DESIGN

Retrospective analysis of data from a randomized controlled trial.

PARTICIPANTS

One hundred ninety-eight ocular hypertensive and 21 control subjects.

METHODS

Change criteria were derived from rim area (RA) repeatability coefficients for different levels of image quality. Event analysis 1 (EA1) through EA4 were applied to longitudinal series of HRT images acquired from the ocular hypertensive and the control cohorts: EA1 (change confirmed in 2 of 3 consecutive tests in 1 or more sector), EA2 (2 of 3 in 2 or more sectors), EA3 (3 of 3 in 1 or more sector), EA4 (3 of 3 in 2 or more sectors). Specificity (1 minus false positive results) was estimated by the proportions of progressing controls and significantly improving subjects. Progression rates were compared with Advanced Glaucoma Intervention Study (AGIS) visual field (VF) criteria, an HRT trend analysis, and a VF trend analysis, with specificity matched at 95%.

MAIN OUTCOME MEASURES

Estimated specificity, progression rate, and agreement between progression techniques.

RESULTS

Specificity estimates were 76.2% to 88.1% (EA1), 94.1% to 95.2% (EA2), 92.2% to 95.2% (EA3), and 99.1% to 100% (EA4). Of ocular hypertensive (OHT) subjects, 45.4%, 28.3%, 26.3%, and 16.2% were identified as progressing by each strategy, respectively. With specificity at 95%, 12.1% of OHT subjects progressed by both EA2 and AGIS criteria, with a median time to progression of 3.2 and 3.6 years, respectively. By EA2 alone, 16.2% progressed, and 9.6% progressed by AGIS criteria alone. The RA trend analysis identified 12% of OHT subjects as progressing.

CONCLUSIONS

The HRT EA represents a simple technique, taking into account image quality. In this cohort, it had a higher detection rate of progression, at 95% specificity, than RA trend analysis and the VF progression criteria.

Sector-based analysis of frequency doubling technology sensitivity and optic nerve head shape parameters

PURPOSE

To evaluate which Heidelberg Retina Tomograph (HRT) parameter is the best predictor of frequency doubling technology (FDT) sensitivity by using a sector based analysis between FDT and optic nerve head shape parameters such as cup shape measure (CSM) and rim area (RA), which have been shown to have the best correlation with FDT indices among all the HRT parameters.

METHODS

One eye was randomly chosen from 100 patients with primary open angle glaucoma (abnormal visual field and/or abnormal optic nerve and untreated intraocular pressure above 21 mm Hg). All the patients were examined with Humphrey field analyzer (HFA), program 24-2, SITA standard, FDT program C 20, and HRT. RA and CSM for the HRT analysis and mean deviation, pattern standard deviation, and the sensitivity of each tested point for the FDT test were considered in this study. All the parameters were calculated as both global and sector measurements. Findings were analyzed using Pearson's correlation coefficient and linear regression model.

RESULTS

Significant (p<0.001) correlation was found between FDT indices and HRT RA and CSM. Significant (p<0.001) sector correlation was found between FDT sensitivity and RA and CSM, but when a linear regression model was applied, RA was the most predictive parameter of FDT. Temporal CSM was more strongly correlated to FDT fovea sensitivity than temporal RA. Furthermore, sector HRT parameters were better correlated to HFA than to FDT.

CONCLUSIONS

In this glaucomatous group, cup shape measure and RA were significantly correlated to FDT indices. RA was more predictive of FDT abnormality than CSM in all the considered sectors except in the temporal one. However, HFA was a stronger predictor of HRT parameters than FDT.

The relationship between structural and functional alterations in glaucoma: a review

This article reviews the relationships between structural changes and visual function losses produced by glaucomatous damage. Structural characteristics of the optic nerve head and retinal nerve fiber layer include both qualitative and semi-quantitative clinical assessment methods as well as quantitative imaging techniques. Visual function properties include standard (white-on-white) automated perimetry and new techniques such as short wavelength automated perimetry and motion displacement threshold perimetry. Previous investigations consistently report a significant relationship between structural and functional deficits in glaucoma, with structural changes usually being reported to occur earlier than functional losses. In cases of focal damage, there appears to be a good topographic relationship between structural and functional losses. Several optic nerve head and retinal nerve fiber layer measures are reported to be good predictors of glaucomatous visual field loss. However, previous investigations of structure-function relationships in glaucoma are limited by the small number of patients evaluated in most studies, the lack of well-defined inclusion/exclusion criteria as well as detailed descriptions of the patient population, and the paucity of prospective longitudinal studies that have been performed.

Diagnostic ability of Heidelberg Retina Tomograph 3 classifications: glaucoma probability score versus Moorfields regression analysis

PURPOSE

To evaluate the usefulness of the glaucoma probability score (GPS), which does not require manual outlining of the disc boundaries, and the Moorfields regression classification (MRA), which requires manual outlining of the disc boundaries, for discriminating between healthy and glaucomatous eyes, using the Heidelberg Retina Tomograph.

DESIGN

Cross-sectional study.

PARTICIPANTS

We prospectively selected 71 consecutive healthy subjects and 115 consecutive patients with open-angle glaucoma.

METHODS

Participants were divided into 2 groups depending on the results of standard automated perimetry and intraocular pressure. All participants underwent imaging of the optic nerve head with the Heidelberg Retina Tomograph 3. All tests were performed within 1 month of each subject's date of enrollment into the study by examiners masked to the other findings.

MAIN OUTCOME MEASURES

The sensitivity and specificity of all parameters of the MRA and GPS classifications were calculated. The diagnostic accuracy at different severities of glaucoma and optic disc sizes was also evaluated. Receiver operating characteristic curves were plotted for the GPS values.

RESULTS

The MRA global classification had a sensitivity of 73.9% and a specificity of 91.5%. The GPS global classification had a sensitivity of 58.2% and a specificity of 94.4%. The GPS had slightly higher sensitivity and somewhat lower specificity than the MRA when there was mild damage indicated by visual field tests. The MRA had the best discrimination capability for moderate and severe glaucoma. Both the GPS and MRA had lower sensitivity and higher specificity for small optic discs (<1.7 mm2) compared with medium and large discs.

CONCLUSIONS

In general, the diagnostic performance of the GPS was similar to that of the MRA. The diagnostic accuracy of both classifications depends on the optic disc size and the glaucoma severity.

Sensitivity and specificity of Heidelberg Retinal Tomography II parameters in detecting early and moderate glaucomatous damage: effect of disc size

PURPOSE

To determine the efficacy of Heidelberg Retinal Tomography II (HRTII) parameters in differentiating normal eyes from eyes with early or moderate glaucomatous damage.

METHODS

HRTII tests were performed on 70 eyes of 70 patients with early or moderate glaucomatous damage, and 70 eyes of 70 healthy subjects. HRTII stereometric parameters, global and sectorial rim area parameters were recorded. Sensitivity and specificity of each parameter were calculated. Cases were divided into three groups according to disc size as large, medium and small, and mean values of parameters in glaucoma and control groups were compared.

RESULTS

Mean disc area was larger in the glaucoma group (P < 0.05). There was a significant difference between the two groups for all stereometric parameters, except height variation contour, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross-sectional area stereometric parameters. There was also a significant difference between the groups for global, temporal, superior temporal and inferior temporal rim area parameters. In small discs, however, this difference disappeared in all parameters except temporal rim area and superior temporal rim area sectorial parameters. When all the cases were included, the quartet parameters having the highest specificity (80%) and sensitivity (74.3%) were cup volume, rim volume, cup shape measure and height variation contour parameters.

CONCLUSION

Some HRTII parameters have better sensitivity and specificity than the others. It is necessary to pay special attention in evaluating small discs.