Normative Databases Research Articles

Peripapillary retinal nerve fibre layer thickness measurement with SD-OCT in normal and glaucomatous eyes: distribution and correlation with age.

To determine peripapillary retinal fiber layer thickness (RNFL) measured with spectral domain optical coherence tomography (SD-OCT) in normal and glaucomatous eyes in a large sample of exclusively white population and compare results with other similarly constructed studies. Average, maximum, minimum and per quadrant RNFL thickness were measured in normal and glaucomatous Greek patients with a scanning laser ophthalmoscope (SLO)/SD-OCT device. The effect of age in normal RNFL thickness was also determined. A total of 278 normal (278 patients) and 67 glaucomatous (67 patients) eyes were included in the study. Average RNFL thickness was 114.8±13.3µm in normal and 92.1±18.5µm in glaucomatous eyes (P<0.001). In normal discs, superior quadrant was the thickest, followed by the inferior, nasal and temporal. Decline of normal RNFL thickness with age was statistically significant for average RNFL thickness (1.92µm per decade of life) and for the superior and inferior quadrants of the disc. SD-OCT peripapillary RNFL measurements can be used to distinguish between normal and glaucomatous eyes and establish normative databases, since normal disc measurements differ between different ethnic groups and between different SD-OCT devices.

2013 International Society for Clinical Densitometry Position Development Conference: Task Force on Normative Databases

Following the standard protocol for development of Official Positions for the International Society for Clinical Densitometry, the Expert Panel heard the report and recommendations from the Task Force on Normative Databases; using the RAND methodology, agreement was reached on the following statements:1. Manufacturers should continue to use their own databases for the lumbar spine as the reference standard for T-scores.2. Manufacturers should continue to use National Health and Nutrition Examination Survey III data as the reference standard for femoral neck and total hip T-scores.3. If local reference data are available, they should be used to calculate only Z-scores but not T-scores.4. A uniform Caucasian (non-race adjusted) female reference database should be used to calculate T-scores for men of all ethnic groups.

Comparison of ability of time-domain and spectral-domain optical coherence tomography to detect diffuse retinal nerve fiber layer atrophy

Our aim was to evaluate and compare diagnostic capabilities of time-domain (Stratus) and spectral-domain (Cirrus) optical coherence tomography (OCT) to detect diffuse retinal nerve fiber layer (RNFL) atrophy. This study assessed 101 eyes from 101 glaucoma patients with diffuse RNFL atrophy and 101 eyes from 101 age-matched healthy individuals. Two experienced glaucoma specialists graded red-free RNFL photographs of eyes with diffuse RNFL atrophy using a four-level grading system. The area under the receiver operating characteristic curves (AUC) of normal eyes was compared with that of eyes with diffuse atrophy. Sensitivity and specificity of each OCT device were calculated on the basis of its internal normative database. The largest AUC for Stratus and Cirrus were obtained for average RNFL thicknesses (0.96 and 0.94, respectively). Comparison of the AUC with different RNFL atrophy grades revealed no significant difference between the two OCT devices. Using an internal normative database at a <5% level, the overall sensitivity of Stratus ranged from 58.0 to 84.0%, whereas that of Cirrus ranged from 75.0 to 87.0%. According to the normative database, the highest Stratus sensitivity was obtained with the temporal-superior-nasal-inferior-temporal (TSNIT) thickness graph, and the highest Cirrus sensitivity with the TSNIT thickness graph and the deviation map. The AUC obtained from Cirrus were comparable with those from Stratus. On the basis of their normative databases, these devices had similar diagnostic accuracy. Our results suggest that the diagnostic capabilities of the two instruments to detect diffuse RNFL atrophy are similar.

Normalization of the psychometric hepatic encephalopathy score in Polish population. A prospective, quantified electroencephalography study

The psychometric hepatic encephalopathy score (PHES) is recommended as a gold standard in evaluation of minimal hepatic encephalopathy (HE). Normative databases have been collected in few countries, clearly showing differences among studied groups. Thus, the standardization of PHES for selected populations remains necessary. To standardize PHES in a large cohort of Polish healthy subjects and to evaluate the normograms in patients with cirrhosis with quantified electroencephalography (EEG). Three hundred and sixteen (142 males/174 females, aged 44.5±12.1) normal individuals and 50 (31 males/19 females, aged 52.8±12.4) patients with cirrhosis without overt HE were included. Key correction variables of psychometric tests were performed. The multivariate linear regression was used to calculate PHES normograms. Age and education levels were identified as predictors of all tests, therefore age- and education-adjusted normograms were developed. A weighted time-errors regression model for line tracing test (LTT) scoring was used. The PHES ranged between +5 and -15 points and the cut-off between normal and pathological PHES was set on ≤-5 points. By this cut-off level, PHES had a sensitivity of 57% and specificity of 97% to diagnose minimal HE (AUC=0.866±0.028). In patients with cirrhosis, PHES correlated with severity of liver disease (MELD, r=-0.475, P<0.001 and Child-Pugh classification, r=-0.452, P<0.002) and EEG (r=0.547, P<0.002). In patients with impaired EEG, PHES was lower than in individuals with unaltered EEG (P<0.02); however, agreement between these two modalities was limited. Valid Polish PHES normograms, which incorporates w-LTT scoring system have been developed. Future multi-centre international studies are needed to validate widely applicable norms.

Evidence Based Medicine: Why should we be practicing it all the time?

Evidence Based Medicine: Why should we be practicing it all the time?

EMOTIONS IN TEXT: DIMENSIONAL AND CATEGORICAL MODELS

Text often expresses the writer's emotional state or evokes emotions in the reader. The nature of emotional phenomena like reading and writing can be interpreted in different ways and represented with different computational models. Affective computing (AC) researchers often use a categorical model in which text data are associated with emotional labels. We introduce a new way of using normative databases as a way of processing text with a dimensional model and compare it with different categorical approaches. The approach is evaluated using four data sets of texts reflecting different emotional phenomena. An emotional thesaurus and a bag‐of‐words model are used to generate vectors for each pseudo‐document, then for the categorical models three dimensionality reduction techniques are evaluated: Latent Semantic Analysis (LSA), Probabilistic Latent Semantic Analysis (PLSA), and Non‐negative Matrix Factorization (NMF). For the dimensional model a normative database is used to produce three‐dimensional vectors (valence, arousal, dominance) for each pseudo‐document. This three‐dimensional model can be used to generate psychologically driven visualizations. Both models can be used for affect detection based on distances amongst categories and pseudo‐documents. Experiments show that the categorical model using NMF and the dimensional model tend to perform best.

Glaucoma versus red disease

The use of ophthalmic imaging for documentation and diagnosis of ocular disease is rising dramatically. Optical coherence tomography (OCT), confocal scanning laser tomography (CSLT), scanning laser polarimetry (SLP) and photographic imaging of the optic nerve head (ONH) are currently used to document baseline characteristics of the ONH and for diagnosing glaucoma and glaucoma progression secondary to loss of retinal nerve fiber layer (RNFL). Imaging modalities typically provide information on ONH and RNFL characteristics which are outside of the normal (relative to normative databases) in red lettering or boxes, whereas ONH and RNFL characteristics within the normal range are presented in green. As imaging modalities have become more sophisticated and are validated in research studies, clinicians have come to rely upon data from these imaging devices to aid in differentiating between normal and glaucomatous states of the ONH and RNFL - typically by examining if the data are green or red suggesting normal or abnormal. However, normative databases can sometimes be flawed relative to atypical ONH or RNFL morphologies and imaging can provide artifacts which do not represent true ocular disease but secondary to limitations of imaging technology. Ophthalmic imaging is an important adjunct to clinical diagnosis but the results from imaging devices need to be assessed critically relative to artifacts of imaging and the limitations of the technology and its normative databases.

The functional magnetic resonance imaging-based verbal fluency test in obsessive–compulsive disorder

Clinical use of functional magnetic resonance imaging (fMRI) in obsessive–compulsive disorder (OCD) is limited by a relative absence of fMRI task development, standardization, and normative performance databases. We investigated the fMRI-based verbal fluency test (f-VFT) by quantitatively evaluating brain activation patterns in OCD participants (8 females and 4 males) compared with a normative database (16 females and 16 males). At the group level, OCD participants and references had highly similar activation in left-hemisphere language regions, including the precentral/premotor cortex, thalamus, basal ganglia, and inferior frontal gyrus/frontal operculum. At the interindividual level, however, the OCD group had highly variable activation patterns in the dorsal and ventral regions of the pre-supplementary motor area (pre-SMA) that may correspond with differences in demographic and clinical variables. Further, there were significant correlations in the OCD participants between pre-SMA dorsal and ventral activation and between dorsal pre-SMA activation and perfectionism. Our findings suggest considerable functional anatomical overlap in left-hemisphere language regions between OCD participants and references but significantly higher pre-SMA interindividual variability in OCD compared to the reference group that may be relevant in clinical fMRI application and the theoretical understanding of OCD.

Chamber and Vessel Quantification in Pediatric Echocardiography: What Do the Guidelines Teach Us?

The American Society of Echocardiography has recently published guidelines for chamber and vessel quantification during a pediatric echocardiogram. Because the sizes of cardiovascular structures increase with somatic growth, pediatric quantification requires the adjustment of measurements for the effects of body size in order to determine when a measurement is outside the normal range. A universal pediatric normative database of measurements from a normal population encompassing the full range of body sizes encountered in pediatrics would provide clinicians and researchers a powerful tool to distinguish normal from abnormal values and aid in the management of children with heart disease. However, there are still challenges in the complete acceptance of the recommended pediatric protocols for each cardiac segment, mostly because of historical standard practices, differences with the quantification guidelines for adults, and varying methodologies utilized in currently available pediatric normative databases.

Multimodal Quantitative Neuroimaging Databases and Methods: The Cuban Human Brain Mapping Project

This article reviews the contributions of the Cuban Neuroscience Center to the evolution of the statistical parametric mapping (SPM) of quantitative Multimodal Neuroimages (qMN), from its inception to more recent work. Attention is limited to methods that compare individual qMN to normative databases (n/qMN). This evolution is described in three successive stages: (a) the development of one variant of normative topographical quantitative EEG (n/qEEG-top) which carries out statistical comparison of individual EEG spectral topographies with regard to a normative database--as part of the now popular SPM of brain descriptive parameters; (b) the development of n/qEEG tomography (n/qEEG-TOM), which employs brain electrical tomography (BET) to calculate voxelwise SPM maps of source spectral features with respect to a norm; (c) the development of a more general n/qMN by substituting EEG parameters with other neuroimaging descriptive parameters to obtain SPM maps. The study also describes the creation of Cuban normative databases, starting with the Cuban EEG database obtained in the early 90s, and more recently, the Cuban Human Brain Mapping Project (CHBMP). This project has created a 240 subject database of the normal Cuban population, obtained from a population-based random sample, comprising clinical, neuropsychological, EEG, MRI and SPECT data for the same subjects. Examples of clinical studies using qMN are given and, more importantly, receiver operator characteristics (ROC) analyses of the different developments document a sustained effort to assess the clinical usefulness of the techniques.

Approach to the Child with Fractures

Evaluation of the child with fractures is challenging, as no clear guidelines exist to distinguish traumatic from pathological fractures. Although most fractures in childhood are benign, recurrent fractures may be associated with a wide variety of primary skeletal diseases as well as secondary causes, necessitating a careful history and physical exam to guide the evaluation. There is no "gold standard" for the evaluation and treatment of children with fractures and low bone mineral density (BMD); therefore, the diagnosis of osteoporosis in a pediatric patient should be made using a combination of clinical and radiographic features. Interpretation of bone densitometry in growing patients presents a unique set of challenges because areal BMD measured by dual-energy x-ray absorptiometry depends on multiple dynamic variables. Interpretation of pediatric dual-energy x-ray absorptiometry should be based on Z-scores (sd scores compared to age, sex, and ethnicity-matched controls), using normative databases specific to the brand of densitometer and the patient population. Given the skeleton's ability to recover from low BMD through modeling and remodeling, optimizing management of underlying conditions leading to bone fragility is the initial step. Conservative measures including calcium and vitamin D supplementation and weight-bearing physical activity are important interventions that should not be overlooked. The use of bisphosphonates in children and adolescents is controversial due to lack of long-term efficacy and safety data and should be limited to clinical trials and compassionate therapy in children with significantly compromised quality of life. Close monitoring is required, and further study is necessary to assess their long-term safety and efficacy in children.

Low-Luminance Contrast Stimulation Is Optimal for Early Detection of Glaucoma Using Multifocal Visual Evoked Potentials

The blue-on-yellow multifocal visual evoked potential (BonY mfVEP) stimulus is more sensitive than the conventional black-and-white pattern-reversal stimulus in identifying early glaucoma. BonY employs pattern-onset stimulation and lower luminance contrast (40%) in addition to color. This study was conducted to elucidate the mechanism responsible for the enhanced performance of the BonY stimulus. Multifocal pattern-onset VEPs were recorded in response to BonY, high-luminance contrast achromatic (HLA) and low-luminance contrast achromatic (LLA) stimulations in 30 normal subjects (to construct normative databases) and 23 patients with early glaucoma (mean deviation [MD] < 6 dB). In addition, the specificity of BonY and LLA stimulation was examined in a subset of 25 normal subjects. In normal subjects, LLA mfVEPs had significantly lower amplitudes than did BonY and HLA mfVEPs (P < 0.001), which were not significantly different from each other. In glaucomatous eyes, all three stimuli demonstrated significantly reduced amplitudes in comparison with those of normal eyes. Although the sensitivities of both BonY and LLA in identifying subjective visual field defects were similarly high (93% and 89.7%, respectively), HLA showed only a 79.3% detection rate. BonY and LLA demonstrated significantly higher defect severity scores than did HLA (P < 0.05 for both). Specificities for BonY and LLA were similar (96%). BonY and LLA mfVEPs performed comparably, and both were significantly better than the HLA mfVEP in identifying early glaucoma. Enhanced performance of BonY stimulation is most likely due to its low-luminance contrast component rather than the pattern-onset mode of presentation or its chromatic properties.

Assessing Errors Inherent in OCT-Derived Macular Thickness Maps

SD-OCT has become an essential tool for evaluating macular pathology; however several aspects of data collection and analysis affect the accuracy of retinal thickness measurements. Here we evaluated sampling density, scan centering, and axial length compensation as factors affecting the accuracy of macular thickness maps. Forty-three patients with various retinal pathologies and 113 normal subjects were imaged using Cirrus HD-OCT. Reduced B-scan density was associated with increased interpolation error in ETDRS macular thickness plots. Correcting for individual differences in axial length revealed modest errors in retinal thickness maps, while more pronounced errors were observed when the ETDRS plot was not positioned at the center of the fovea (which can occur as a result of errant fixation). Cumulative error can exceed hundreds of microns, even under “ideal observer” conditions. This preventable error is particularly relevant when attempting to compare macular thickness maps to normative databases or measuring the area or volume of retinal features.

Land use data generalization indices considering scale and land use pattern effects

Land use generalization indices are critical for producing normative multi-scale land use databases and maps, but there is still not a national criterion for these indices in China. Previous studies on land use data generalization indices often neglect macro-indices such as area proportion of land use types and map load, and also ignore landscape effects on land use generalization indices. Here we constructed an index system of land use data generalization from macro- and micro-perspectives, and examined scale and landscape effects on land use data generalization indices based on the countrywide multi-scale land use data samples. We formulated relationships between land use data generalization indices and both scale and land use pattern metrics. We defined thresholds of land use data generalization indices on scales of 1:50000, 1:100000, 1:250000, and 1:500000. We verified our methodology and index thresholds through generalizing a county land use database.

Group independent component analysis of resting state EEG in large normative samples

EEG (Electroencephalography) resting state was studied by means of group blind source separation (gBSS), employing a test–retest strategy in two large-sample normative databases (N = 57 and N = 84). Using a BSS method in the complex Fourier domain and a model-driven distributed inverse solution we closely replicate both the spatial distribution and spectral pattern of seven source components. Norms were then constructed for their spectral power so as to allow testing patients against the norms. As compared to existing normative databases based on scalp spectral measures, the resulting tool defines a smaller number of features with very little inter-correlation. Furthermore, these features are physiologically meaningful as they relate the activity of several brain regions, forming a total of seven patterns, each with a peculiar spatial distribution and spectral profile. This new tool, that we name normative independent component analysis (NICA), may serve as an adjunct to diagnosis and assessment of abnormal brain functioning and aid in research on normal resting state networks.

QEEG Evaluation of the LENS Treatment of TBI

Previous publications have reported encouraging preliminary clinical outcomes in the treatment of a variety of problems with the Low Energy Neurofeedback System (LENS). However, no previous publication has evaluated outcomes with quantitative EEG (QEEG) comparisons to normative databases. This article presents outcomes from the LENS treatment of a patient who suffered a serious traumatic brain injury 9 years earlier. After 42 sessions of treatment, the patient, now 16 years old, had very significant clinical improvements as well as documented changes in QEEG measures. Further outcome studies involving pre- and posttreatment QEEG evaluations are needed.

Expanded norms for 400 experimental pictures in an Argentinean Spanish-speaking population

The study of the cognitive processes in the production of language demands careful selection of stimuli and requires normative databases. The main goal of the present research was to collect normative data for the set of 400 figures taken from Cycowicz, Friedman, Rothstein, and Snodgrass (1997; including the 260 figures of Snodgrass & Vanderwart, 1980) using a sample of native Argentinean Spanish speakers. The pictures have been standardized on the following variables: name agreement, image agreement, familiarity, visual complexity, image variability, age of acquisition, and word association. The obtained norms were compared with the normative data of other studies in Spanish, English, and French. This comparison highlights the variability of some of the measures (e.g., name agreement in naming and verbal association) across the different studies and confirms the necessity of elaborating specific norms that are adapted to the studied population's linguistic and sociocultural context. The norms described may be downloaded as supplemental materials for this article from http://brm.psychonomic-journals.org/content/supplemental.

Drs. Coburn, Lauterbach, Boutros, Black, Arciniegas, and Coffey Reply

Back to table of contents Previous article Next article LETTERFull AccessDrs. Coburn, Lauterbach, Boutros, Black, Arciniegas, and Coffey ReplyKerry L. Coburn Ph.D.Edward C. Lauterbach M.D.Nash N. Boutros M.D.Kevin J. Black M.D.David B. Arciniegas M.D.C. Edward Coffey M.D.Kerry L. Coburn Ph.D.Search for more papers by this authorEdward C. Lauterbach M.D.Search for more papers by this authorNash N. Boutros M.D.Search for more papers by this authorKevin J. Black M.D.Search for more papers by this authorDavid B. Arciniegas M.D.Search for more papers by this authorC. Edward Coffey M.D.Search for more papers by this authorPublished Online:1 Jan 2010https://doi.org/10.1176/jnp.2010.22.1.123.e4AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: We appreciate Dr. Coutin-Churchman’s interest in our paper and welcome the opportunity to address his comments. We did indeed refer to his paper as exemplifying many of the difficulties involved in building a clinically applicable qEEG system de novo, but we are unable to locate anywhere in our paper the quotation he attributes to us about “the more complex mathematics involved.” Furthermore, we do not state anywhere in our paper that he used “hypernormals” instead of “street normals” in his normative healthy database. Dr. Coutin-Churchman states that we neglected his observation that “there was a significant statistical trend for some patterns … to be more frequently observed in some disorders.…” However, the paper he refers to is not the one we reviewed, and nowhere in the reviewed paper does his quotation appear. Regarding the issues of statistically significant but clinically trivial “normal variants” and our observation that his qEEG system identified 12% of a healthy group as abnormal, Dr. Coutin-Churchman mixes disparate arguments from two sections of our paper. The false positive observation concerns the statistical adequacy of his healthy normative database, in comparison with other healthy normative databases. The normal variant issue concerns the requirement that the clinical application of qEEG as a diagnostic aid in actual practice must be preceded by a standard visual analysis of the raw EEG by a trained electroencephalographer. There is no double standard here.With regard to the relationship between qEEG abnormalities and diagnosis (a stated aim of their study), Dr. Coutin-Churchman et al. found no relationship. We suggest that their negative finding may have been due to their rejection of multivariate analytic methods and, more fundamentally, a lack of statistical power due to the very small number of cases in many of their diagnostic groups. Dr. Coutin-Churchman defends his small group sizes on the basis of his blind selection of cases, but this seems irrelevant to the questions of analytic technique and statistical adequacy. FiguresReferencesCited byDetailsCited ByNone Volume 22Issue 1 Winter, 2010Pages 123.e4-123.e4 Metrics PDF download History Published online 1 January 2010 Published in print 1 January 2010

Drs. Coburn, Lauterbach, Boutros, Black, Arciniegas, and Coffey Reply

Back to table of contents Previous article Next article LETTERFull AccessDrs. Coburn, Lauterbach, Boutros, Black, Arciniegas, and Coffey ReplyKerry L. Coburn Ph.D.Edward C. Lauterbach M.D.Nash N. Boutros M.D.Kevin J. Black M.D.David B. Arciniegas M.D.C. Edward Coffey M.D.Kerry L. Coburn Ph.D.Search for more papers by this authorEdward C. Lauterbach M.D.Search for more papers by this authorNash N. Boutros M.D.Search for more papers by this authorKevin J. Black M.D.Search for more papers by this authorDavid B. Arciniegas M.D.Search for more papers by this authorC. Edward Coffey M.D.Search for more papers by this authorPublished Online:1 Jan 2010https://doi.org/10.1176/jnp.2010.22.1.123.e4AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: We appreciate Dr. Coutin-Churchman’s interest in our paper and welcome the opportunity to address his comments. We did indeed refer to his paper as exemplifying many of the difficulties involved in building a clinically applicable qEEG system de novo, but we are unable to locate anywhere in our paper the quotation he attributes to us about “the more complex mathematics involved.” Furthermore, we do not state anywhere in our paper that he used “hypernormals” instead of “street normals” in his normative healthy database. Dr. Coutin-Churchman states that we neglected his observation that “there was a significant statistical trend for some patterns … to be more frequently observed in some disorders.…” However, the paper he refers to is not the one we reviewed, and nowhere in the reviewed paper does his quotation appear. Regarding the issues of statistically significant but clinically trivial “normal variants” and our observation that his qEEG system identified 12% of a healthy group as abnormal, Dr. Coutin-Churchman mixes disparate arguments from two sections of our paper. The false positive observation concerns the statistical adequacy of his healthy normative database, in comparison with other healthy normative databases. The normal variant issue concerns the requirement that the clinical application of qEEG as a diagnostic aid in actual practice must be preceded by a standard visual analysis of the raw EEG by a trained electroencephalographer. There is no double standard here.With regard to the relationship between qEEG abnormalities and diagnosis (a stated aim of their study), Dr. Coutin-Churchman et al. found no relationship. We suggest that their negative finding may have been due to their rejection of multivariate analytic methods and, more fundamentally, a lack of statistical power due to the very small number of cases in many of their diagnostic groups. Dr. Coutin-Churchman defends his small group sizes on the basis of his blind selection of cases, but this seems irrelevant to the questions of analytic technique and statistical adequacy. FiguresReferencesCited byDetailsCited byNone Volume 22Issue 1 Winter, 2010Pages 123.e4-123.e4 Metrics PDF download History Published online 1 January 2010 Published in print 1 January 2010

Comparison of Glaucoma Diagnostic Capabilities of Cirrus HD and Stratus Optical Coherence Tomography

To compare the glaucoma diagnostic capabilities offered by Stratus and Cirrus spectral-domain optical coherence tomography (OCT). One hundred subjects with glaucoma and 74 healthy subjects were tested by Stratus and Cirrus OCT. Areas under the receiver operating characteristic curves (AUCs) of average, 4-quadrant, and 12-sector retinal nerve fiber layer thicknesses and sensitivities at fixed specificities (80% and 90%) were compared when the 2 OCT modalities were used to evaluate patients with early or moderate to advanced glaucoma. Likelihood ratios using normative classifications were reported. Overall, both OCT instruments showed similar glaucoma discrimination capability in average retinal nerve fiber layer thickness (AUC, 0.953 [Cirrus] vs 0.934 [Stratus]; P = .15). Cirrus OCT displayed significantly higher AUCs in the average, inferior, temporal, and superior quadrants and 7-o'clock measurements in early stages of glaucoma. The between-OCT instrument AUCs did not differ significantly in moderate to advanced stages. Abnormal results for both OCT instruments, after comparison with their normative databases, were associated with high likelihood ratios. In our series, the Cirrus OCT showed better glaucoma discrimination capability than Stratus OCT in early stages of glaucoma. Our findings suggest that spectral-domain technology of OCT may offer an improved capability of early-stage glaucoma detection.