New developments in Heidelberg retina tomograph for glaucoma

Estimation of normal and glaucomatous optic nerve morphology from perfusion

OBJECTIVE

To estimate the optic nerve head morphology from its haemoglobin (Hb) distribution.

METHODS AND ANALYSIS

The optic disc of 189 normal eyes and 292 with confirmed and suspected glaucoma were analysed with Spectralis-OCT and the Laguna ONhE application using the Topcon NW400 fundus camera. Topographic Hb values were correlated with OCT tissue thicknesses from Bruch's membrane. The neuroretinal rim volume (RV), the cup volume (CV) and their relation to the globin distribution function (GDF) index of Laguna ONhE were analysed. The results were applied to 1 163 241 optic nerve images obtained in a glaucoma screening setting. Differences in segmentation and the presence of vessels without local nutritional function are the main limitations of the comparison.

RESULTS

The correlation between local Hb density and the tissue thicknesses from Bruch's membrane was R=0.953 (p<0.0001). RV could be estimated from pixel-to-pixel Hb values with an R=0.650 (p<0.0001) and from six Laguna ONhE indices with an R=0.786 (p<0.0001). CV could be estimated with an R=0.762 (p<0.0001). RV had a mean value of 0.396 mm3 (SD=0.187) for positive GDF values and usually below 0.210 mm3 for negative GDF. The distribution of RV values in the screening series was congruent with that found in the prospective series, with a higher value in large nerves.

CONCLUSIONS

The volume and shape of the optic nerve tissue are closely related to its perfusion and can be deduced from it. The relationship between the RV and GDF is curvilinear and suggests that perfusion measurement may bring the diagnosis forward in earlier stages.

Comparison of Ethnic-specific Databases in Heidelberg Retina Tomography-3 to Discriminate Between Early Glaucoma and Normal Chinese Eyes

Purpose:

To compare the diagnostic accuracy of the 3 race-specific normative databases in Heidelberg Retina Tomography (HRT)-3, in differentiating between early glaucomatous and healthy normal Chinese eyes.

Method:

52 healthy volunteers and 25 glaucoma patients were recruited for this prospective cross-sectional study. All underwent standardized interviews, ophthalmic examination, perimetry and HRT optic disc imaging. Area under the curve (AUC) receiver operating characteristics, sensitivity and specificity were derived to assess the discriminating abilities of the 3 normative databases, for both Moorfields Regression Analysis (MRA) and Glaucoma Probability Score (GPS).

Results:

A significantly higher percentage (65%) of patients were classified as “within normal limits” using the MRA-Indian database, as compared to the MRA-Caucasian and MRA-African-American databases. However, for GPS, this was observed using the African-American database. For MRA, the highest sensitivity was obtained with both Caucasian and African-American databases (68%), while the highest specificity was from the Indian database (94%). The AUC for discrimination between glaucomatous and normal eyes by MRA-Caucasian, MRA-African-American and MRA-Indian databases were 0.77 (95% CI, 0.67-0.88), 0.79 (0.69-0.89) and 0.73 (0.63-0.84) respectively. For GPS, the highest sensitivity was obtained using either Caucasian or Indian databases (68%). The highest specificity was seen with the African-American database (98%). The AUC for GPS-Caucasian, GPS-African-American and GPS-Indian databases were 0.76 (95% CI, 0.66-0.87), 0.77 (0.67-0.87) and 0.76 (0.66-0.87) respectively.

Conclusion:

Comparison of the 3 ethnic databases did not reveal significant differences to differentiate early glaucomatous from normal Chinese eyes.

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).

Clinical Signs and Diagnosis of the Canine Primary Glaucomas

The diagnosis of glaucoma is highly dependent on a working understanding of the clinical signs and available diagnostic procedures. Clinical signs may be attributable to increased intraocular pressure and/or complex alterations in the physiology or molecular biology of the anterior segment, retinal ganglion cells, and optic nerve. Many diagnostic procedures seek to more fully characterize these alterations and to identify which clinical features increase the risk of overt primary angle closure glaucoma (PACG) occurring. Considerable progress has been made in identifying the anatomic features that predispose an eye to PACG, and in elucidating the role of reverse pupillary block.

Ageing and ocular surface immunity

Foreword

It gives me pleasure to introduce the 4th edition of the EGS Guidelines. The Third edition proved to be extremely successful, being translated into 7 languages with over 70000 copies being distributed across Europe; it has been downloadable, free, as a pdf file for the past 4 years. As one of the main objectives of the European Glaucoma Society has been to both educate and standardize glaucoma practice within the EU, these guidelines were structured so as to play their part.

Glaucoma is a living specialty, with new ideas on causation, mechanisms and treatments constantly appearing. As a number of years have passed since the publication of the last edition, changes in some if not all of these ideas would be expected.

For this new edition of the guidelines a number of editorial teams were created, each with responsibility for an area within the specialty; updating where necessary, introducing new diagrams and Flowcharts and ensuring that references were up to date. Each team had writers previously involved with the last edition as well as newer and younger members being co-opted.

As soon as specific sections were completed they had further editorial comment to ensure cross referencing and style continuity with other sections.

Overall guidance was the responsibility of Anders Heijl and Carlo Traverso. Tribute must be made to the Task Force whose efforts made the timely publication of the new edition possible.

Roger Hitchings

Chairman of the EGS Foundation

www.eugs.org

The Guidelines Writers and Contributors 

Augusto Azuara Blanco

Luca Bagnasco

Alessandro Bagnis

Keith Barton

Christoph Baudouin

Boel Bengtsson

Alain Bron

Francesca Cordeiro

Barbara Cvenkel

Philippe Denis

Christoph Faschinger

Panayiota Founti

Stefano Gandolfi

David Garway Heath

Francisco Goni

Franz Grehn

Anders Heijl

Roger Hitchings

Gabor Hollo

Tony Hommer

Michele Iester

Jost Jonas

Yves Lachkar

Giorgio Marchini

Frances Meier Gibbons

Stefano Miglior

Marta Misiuk-Hojo

Maria Musolino

Jean Philippe Nordmann

Norbert Pfeiffer

Luis Abegao Pinto

Luca Rossetti

John Salmon

Leo Schmetterer

Riccardo Scotto

Tarek Shaarawy

Ingeborg Stalmans

Gordana Sunaric Megevand

Ernst Tamm

John Thygesen

Fotis Topouzis

Carlo Enrico Traverso

Anja Tuulonen

Ananth Viswanathan

Thierry Zeyen

The Guidelines Task Force 

Luca Bagnasco

Anders Heijl

Carlo Enrico Traverso

Augusto Azuara Blanco

Alessandro Bagnis

David Garway Heath

Michele Iester

Yves Lachkar

Ingeborg Stalmans

Gordana Sunaric Mégevand

Fotis Topouzis

Anja Tuulonen

Ananth Viswanathan

The EGS Executive Committee 

Carlo Enrico Traverso (President)

Anja Tuulonen (Vice President)

Roger Hitchings (Past President)

Anton Hommer (Treasurer)

Barbara Cvenkel

Julian Garcia Feijoo

David Garway Heath

Norbert Pfeiffer

Ingeborg Stalmans

The Board of the European Glaucoma Society Foundation 

Roger Hitchings (Chair)

Carlo E. Traverso (Vice Chair)

Franz Grehn

Anders Heijl

John Thygesen

Fotis Topouzis

Thierry Zeyen

The EGS Committees 

CME and Certification 

Gordana Sunaric Mégevand (Chair)

Carlo Enrico Traverso (Co-chair)

Delivery of Care 

Anton Hommer (Chair)

EU Action 

Thierry Zeyen (Chair)

Carlo E. Traverso (Co-chair)

Education 

John Thygesen (Chair)

Fotis Topouzis (Co-chair)

Glaucogene 

Ananth Viswanathan (Chair)

Fotis Topouzis (Co-chair)

Industry Liaison 

Roger Hitchings (Chair)

Information Technology 

Ingeborg Stalmans (Chair)

Carlo E. Traverso (Co-chair)

National Society Liaison 

Anders Heijl (Chair)

Program Planning 

Fotis Topouzis (Chair)

Ingeborg Stalmans (Co-chair)

Quality and Outcomes 

Anja Tuulonen (Chair)

Augusto Azuara Blanco (Co-chair)

Scientific 

Franz Grehn (Chair)

David Garway Heath (Co-chair)

Optic nerve head parameters of high-definition optical coherence tomography and Heidelberg retina tomogram in perimetric and preperimetric glaucoma

Background:

Heidelberg retina tomogram (HRT) and optical coherence tomography (OCT) are two widely used imaging modalities to evaluate the optic nerve head (ONH) in glaucoma.

Purpose:

To compare the ONH parameters of HRT3 and high-definition OCT (HD-OCT) and evaluate their diagnostic abilities in perimetric and preperimetric glaucoma.

Design:

Cross-sectional analysis.

Methods:

35 control eyes (24 subjects), 21 preperimetric glaucoma eyes (15 patients), and 64 perimetric glaucoma eyes (44 patients) from the Longitudinal Glaucoma Evaluation Study underwent HRT3 and HD-OCT examinations.

Statistical Analysis:

Agreement between the ONH parameters of HRT and HD-OCT were assessed using Bland-Altman plots. Diagnostic abilities of ONH parameters were evaluated using area under the receiver operating characteristic curves (AUCs), sensitivity at fixed specificity, and likelihood ratios (LR).

Results:

Optic disc area, vertical cup to disc ratio, and cup volume with HD-OCT were larger than with HRT, while the rim area was smaller with HD-OCT (P < 0.001 for all comparisons). AUCs of all HD-OCT ONH parameters (0.90-0.97 in perimetric and 0.62-0.71 in preperimetric glaucoma) were comparable (P > 0.10) to the corresponding HRT ONH parameters (0.81-0.95 in perimetric and 0.55-0.72 in preperimetric glaucoma). LRs associated with diagnostic categorization of ONH parameters of both HD-OCT and HRT were associated with larger effects on posttest probability of perimetric compared to preperimetric glaucoma.

Conclusions:

ONH measurements of HD-OCT and HRT3 cannot be used interchangeably. Though the diagnostic abilities of ONH parameters of HD-OCT and HRT in glaucoma were comparable, the same were significantly lower in preperimetric compared to perimetric glaucoma.

Optic nerve head and fibre layer imaging for diagnosing glaucoma

BACKGROUND

The diagnosis of glaucoma is traditionally based on the finding of optic nerve head (ONH) damage assessed subjectively by ophthalmoscopy or photography or by corresponding damage to the visual field assessed by automated perimetry, or both. Diagnostic assessments are usually required when ophthalmologists or primary eye care professionals find elevated intraocular pressure (IOP) or a suspect appearance of the ONH. Imaging tests such as confocal scanning laser ophthalmoscopy (HRT), optical coherence tomography (OCT) and scanning laser polarimetry (SLP, as used by the GDx instrument), provide an objective measure of the structural changes of retinal nerve fibre layer (RNFL) thickness and ONH parameters occurring in glaucoma.

OBJECTIVES

To determine the diagnostic accuracy of HRT, OCT and GDx for diagnosing manifest glaucoma by detecting ONH and RNFL damage.

SEARCH METHODS

We searched several databases for this review. The most recent searches were on 19 February 2015.

SELECTION CRITERIA

We included prospective and retrospective cohort studies and case-control studies that evaluated the accuracy of OCT, HRT or the GDx for diagnosing glaucoma. We excluded population-based screening studies, since we planned to consider studies on self-referred people or participants in whom a risk factor for glaucoma had already been identified in primary care, such as elevated IOP or a family history of glaucoma. We only considered recent commercial versions of the tests: spectral domain OCT, HRT III and GDx VCC or ECC.

DATA COLLECTION AND ANALYSIS

We adopted standard Cochrane methods. We fitted a hierarchical summary ROC (HSROC) model using the METADAS macro in SAS software. After studies were selected, we decided to use 2 x 2 data at 0.95 specificity or closer in meta-analyses, since this was the most commonly-reported level.

MAIN RESULTS

We included 106 studies in this review, which analysed 16,260 eyes (8353 cases, 7907 controls) in total. Forty studies (5574 participants) assessed GDx, 18 studies (3550 participants) HRT, and 63 (9390 participants) OCT, with 12 of these studies comparing two or three tests. Regarding study quality, a case-control design in 103 studies raised concerns as it can overestimate accuracy and reduce the applicability of the results to daily practice. Twenty-four studies were sponsored by the manufacturer, and in 15 the potential conflict of interest was unclear.Comparisons made within each test were more reliable than those between tests, as they were mostly based on direct comparisons within each study.The Nerve Fibre Indicator yielded the highest accuracy (estimate, 95% confidence interval (CI)) among GDx parameters (sensitivity: 0.67, 0.55 to 0.77; specificity: 0.94, 0.92 to 0.95). For HRT measures, the Vertical Cup/Disc (C/D) ratio (sensitivity: 0.72, 0.60 to 0.68; specificity: 0.94, 0.92 to 0.95) was no different from other parameters. With OCT, the accuracy of average RNFL retinal thickness was similar to the inferior sector (0.72, 0.65 to 0.77; specificity: 0.93, 0.92 to 0.95) and, in different studies, to the vertical C/D ratio.Comparing the parameters with the highest diagnostic odds ratio (DOR) for each device in a single HSROC model, the performance of GDx, HRT and OCT was remarkably similar. At a sensitivity of 0.70 and a high specificity close to 0.95 as in most of these studies, in 1000 people referred by primary eye care, of whom 200 have manifest glaucoma, such as in those who have already undergone some functional or anatomic testing by optometrists, the best measures of GDx, HRT and OCT would miss about 60 cases out of the 200 patients with glaucoma, and would incorrectly refer 50 out of 800 patients without glaucoma. If prevalence were 5%, e.g. such as in people referred only because of family history of glaucoma, the corresponding figures would be 15 patients missed out of 50 with manifest glaucoma, avoiding referral of about 890 out of 950 non-glaucomatous people.Heterogeneity investigations found that sensitivity estimate was higher for studies with more severe glaucoma, expressed as worse average mean deviation (MD): 0.79 (0.74 to 0.83) for MD < -6 db versus 0.64 (0.60 to 0.69) for MD ≥ -6 db, at a similar summary specificity (0.93, 95% CI 0.92 to 0.94 and, respectively, 0.94; 95% CI 0.93 to 0.95; P < 0.0001 for the difference in relative DOR).

AUTHORS' CONCLUSIONS

The accuracy of imaging tests for detecting manifest glaucoma was variable across studies, but overall similar for different devices. Accuracy may have been overestimated due to the case-control design, which is a serious limitation of the current evidence base.We recommend that further diagnostic accuracy studies are carried out on patients selected consecutively at a defined step of the clinical pathway, providing a description of risk factors leading to referral and bearing in mind the consequences of false positives and false negatives in the setting in which the diagnostic question is made. Future research should report accuracy for each threshold of these continuous measures, or publish raw data.

Flicker defined form, standard perimetry and Heidelberg retinal tomography: Structure-function relationships

OBJECTIVE

To compare flicker defined form (FDF) perimetry using the Heidelberg edge perimeter (HEP) with standard automated perimetry (SAP) on the Humphrey visual field (HVF) analyzer and to compare their relationship to structural measurements acquired with the Heidelberg retina tomograph.

DESIGN

Prospective, observational study.

PARTICIPANTS

Thirty-one glaucomatous eyes with varying severity and 13 normal control eyes were included in this analysis.

METHODS

All subjects underwent FDF testing on the HEP using the 24-2 protocol by the adaptive staircase thresholding algorithm standard strategy and SAP on the HVF analyzer 750 II using the SITA-Standard 24-2 test. Heidelberg retina tomography (HRT) testing was obtained for each patient. Spearman correlation coefficient, mean deviation (MD), and pattern standard deviation measurements by both machines were compared.

RESULTS

FDF and SAP MD were significantly correlated (r = 0.81, p < 0.001). FDF and SAP MD were significantly correlated with HRT cup/disc ratio (FDF MD: p < 0.001; SAP MD: p = 0.003), disc area (FDF MD: p = 0.005; SAP MD: p = 0.059), rim volume (FDF MD: p < 0.001; SAP MD: p < 0.001), and retinal nerve fibre layer (FDF MD: p < 0.001; SAP MD: p < 0.001).

CONCLUSIONS

This pilot study shows that the MD parameter of FDF correlated with SAP results. FDF and SAP had significant correlations with HRT parameters in glaucomatous and healthy eyes. The potential utility of FDF in the clinical management of glaucoma requires further investigation.

How to detect progression in glaucoma

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

HRT for the Diagnosis and Detection of Glaucoma Progression

Confocal scanning laser ophthalmoscopy through the Heidelberg Retina Tomograph (HRT) provides a rapid, safe, noncontact, and noninvasive imaging of the optic disc in three-dimensions, and provides precise detailed information about the optic disc beyond that which the clinical exam can measure. The HRT I was developed for research purposes only and was not used clinically. The HRT II was developed to be user-friendly, more rapid, and was used as an adjunct to clinical examination in the detection and progression of glaucoma. One of the main pitfalls of the HRT II was that it was operator-dependent. The HRT III was developed to be operator-independent. Initially the Moorsfield Regression Analysis provided the analysis of the stereometric optic disc parameters. The Glaucoma Probability Score, given its ease of use, operator-independence, and rapidity of use, soon gained popularity. Numerous studies have compared these two methods of analysis, with the conclusion that the Glaucoma Probability Score provides a higher sensitivity and a lower specificity than the Moorsfield Regression Analysis, which may indicate that it has potential as a screening test for glaucoma. However, there is no consensus on the use of the Glaucoma Probability Score as a screening test for glaucoma. While HRT data may be useful as a clinical adjunct in the screening and diagnosis of glaucoma, it should ultimately only be used to support clinical examination.

A survey of current and anticipated use of standard and specialist equipment by UK optometrists

PURPOSE

To investigate current and anticipated use of equipment and information technology (IT) in community optometric practice in the UK, and to elicit optometrists' views on adoption of specialist equipment and IT.

METHODS

An anonymous online questionnaire was developed, covering use of standard and specialist diagnostic equipment, and IT. The survey was distributed to a random sample of 1300 UK College of Optometrists members.

RESULTS

Four hundred and thirty-two responses were received (response rate = 35%). Enhanced (locally commissioned) or additional/separately contracted services were provided by 73% of respondents. Services included glaucoma repeat measures (30% of respondents), glaucoma referral refinement (22%), fast-track referral for wet age-related macular degeneration (48%), and direct cataract referral (40%). Most respondents (88%) reported using non-contact/pneumo tonometry for intra-ocular pressure measurement, with 81% using Goldmann or Perkins tonometry. The most widely used item of specialist equipment was the fundus camera (74% of respondents). Optical Coherence Tomography (OCT) was used by 15% of respondents, up from 2% in 2007. Notably, 43% of those anticipating purchasing specialist equipment in the next 12 months planned to buy an OCT. 'Paperless' records were used by 39% of respondents, and almost 80% of practices used an electronic patient record/practice management system. Variations in responses between parts of the UK reflect differences in the provision of the General Ophthalmic Services contract or community enhanced services. There was general agreement that specialised equipment enhances clinical care, permits increased involvement in enhanced services, promotes the practice and can be used as a defence in clinico-legal cases, but initial costs and ongoing maintenance can be a financial burden. Respondents generally agreed that IT facilitates administrative flow and secure exchange of health information, and promotes a state-of-the-art practice image. However, use of IT may not save examination time; its dynamic nature necessitates frequent updates and technical support; the need for adequate training is an issue; and security of data is also a concern.

CONCLUSION

UK optometrists increasingly employ modern equipment and IT services to enhance patient care and for practice management. While the clinical benefits of specialist equipment and IT are appreciated, questions remain as to whether the investment is cost-effective, and how specialist equipment and IT may be used to best advantage in community optometric practice.

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.

Can an inexperienced observer accurately plot disc contours using Heidelberg retinal Tomograph?

OBJECTIVE

To examine the reliability of inexperienced observers in plotting optic disc contours on Heidelberg retinal tomography images before and after training.

DESIGN

Observational study.

PARTICIPANTS

One hundred eyes that were randomly selected from the Singapore Indian Eye Study.

METHODS

Both eyes of subjects were imaged with Heidelberg Retina Tomograph 3 (HRT-3; Heidelberg Engineering, Heidelberg, Germany). Optic disc contours were plotted on the same images by 2 new observers on 2 separate occasions, before and after 2-hour standardized training on the skills and tools available to accurately identify and delineate optic disc contours. These plottings were compared with an experienced, trained glaucoma expert (gold standard). Agreement and variability were analyzed by interclass correlation tests and Bland-Altman plots.

RESULTS

A total of 182 images (18 excluded because of poor quality) from 89 Indian subjects were included. The mean age was 53.27 ± 7.25 years and 54.8% were male. There was moderate-to-high agreement between pretraining (both new observers) and experienced observer's results (interclass correlation values range, 0.76-0.99). The interclass correlation improved for all the HRT-3 parameters after the 2 new observers were adequately trained. Comparing the interclass correlation values before and after training, the differences for mean retinal nerve fibre layer thickness for Observer 1 and all the HRT-3 parameters for Observer 2 were statistically significant.

CONCLUSIONS

This study shows that it is easy to train a new inexperienced observer to plot optic disc contours on HRT images, which translates into improved and acceptable interobserver variability and agreement.

Clinical significance of optic disc progression by topographic change analysis maps in glaucoma: an 8-year follow-up study

Aim. To investigate the ability of Heidelberg Retina Tomograph (HRT3) Topographic Change Analysis (TCA) map to predict the subsequent development of clinical change, in patients with glaucoma. Materials. 61 eyes of 61 patients, which, from a retrospective review were defined as stable on optic nerve head (ONH) stereophotographs and visual field (VF), were enrolled in a prospective study. Eyes were classified as TCA-stable or TCA-progressed based on the TCA map. All patients underwent HRT3, VF, and ONH stereophotography at 9–12 months intervals. Clinical glaucoma progression was determined by masked assessment of ONH stereophotographs and VF Guided Progression Analysis. Results. The median (IQR) total HRT follow-up period was 8.1 (7.3, 9.1) years, which included a median retrospective and prospective follow-up time of 3.9 (3.1, 5.0) and 4.0 (3.5, 4.7) years, respectively. In the TCA-stable eyes, VF and/or photographic progression occurred in 5/13 (38.4%) eyes compared to 11/48 (22.9%) of the TCA-progressed eyes. There was no statistically significant association between TCA progression and clinically relevant (photographic and/or VF) progression (hazard ratio, 1.18; P = 0.762). The observed median time to clinical progression from enrollment was significantly shorter in the TCA-progressed group compared to the TCA-stable group (P = 0.04). Conclusion. Our results indicate that the commercially available TCA progression criteria do not adequately predict subsequent photographic and/or VF progression.

Detecting an event of progression using glaucoma probability score and the stereometric parameters of Heidelberg Retina Tomograph 3

PURPOSE

To evaluate the correlation of the change in glaucoma probability score (GPS) and the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT)3 to an event of glaucomatous progression observed with stereoscopic ONH photography.

METHODS

The subjects for this retrospective follow-up study were monitored with the HRT and stereoscopic ONH photographs. Stable, high-quality imaging and at least 18 months of follow-up was required. The topography examinations were acquired using HRT II and calculated with HRT3 software. The event of progression was determined by masked evaluation of stereoscopic ONH photographs.

RESULTS

A total of 476 eyes of 342 subjects met the inclusion criteria. All the examinations with HRT II were backwards compatible with either the GPS or the stereometric parameters of HRT3. The highest statistical significance for the correlation with progression was observed in the change in cup volume and cup:disc area ratio (p<0.0005). The vertical cup:disc ratio was the parameter with the largest area under the receiver operating characteristics curve (AUC = 0.696). The AUC calculated for the change in GPS was 0.541. The GPS showed no statistically significant correlation with progression (p = 0.213).

CONCLUSIONS

Detecting an event of glaucomatous progression should not be based solely on the change in GPS or the stereometric parameters of the HRT. The good backwards compatibility between HRT II and HRT3 should allow the detection of a trend of glaucomatous progression even when changing from HRT II to HRT3 during the follow-up of glaucoma.

Glaucoma versus red disease: imaging and glaucoma diagnosis

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

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 East London glaucoma prediction score: web-based validation of glaucoma risk screening tool

AIM

It is difficult for Optometrists and General Practitioners to know which patients are at risk. The East London glaucoma prediction score (ELGPS) is a web based risk calculator that has been developed to determine Glaucoma risk at the time of screening. Multiple risk factors that are available in a low tech environment are assessed to provide a risk assessment. This is extremely useful in settings where access to specialist care is difficult. Use of the calculator is educational. It is a free web based service. Data capture is user specific.

METHOD

The scoring system is a web based questionnaire that captures and subsequently calculates the relative risk for the presence of Glaucoma at the time of screening. Three categories of patient are described: Unlikely to have Glaucoma; Glaucoma Suspect and Glaucoma. A case review methodology of patients with known diagnosis is employed to validate the calculator risk assessment.

RESULTS

Data from the patient records of 400 patients with an established diagnosis has been captured and used to validate the screening tool. The website reports that the calculated diagnosis correlates with the actual diagnosis 82% of the time. Biostatistics analysis showed: Sensitivity = 88%; Positive predictive value = 97%; Specificity = 75%.

CONCLUSION

Analysis of the first 400 patients validates the web based screening tool as being a good method of screening for the at risk population. The validation is ongoing. The web based format will allow a more widespread recruitment for different geographic, population and personnel variables.

Agreement between frequency-doubling technology perimetry and Heidelberg retinal tomography 3

PURPOSE

To compare Heidelberg retinal tomography (HRT) 3 and frequency-doubling technology (FDT) perimetry for diagnosis of glaucoma.

METHODS

One eye of each of 117 patients was randomly chosen. The eyes were imaged by HRT3 and tested by FDT. The pattern standard deviation (PSD) and global glaucoma probability score (GPS) were selected as representative output, and sensitivity, specificity, positive predictive value, and negative predictive value determined for each. The agreement between the 2 diagnostic methods was analyzed.

RESULTS

The sensitivity and specificity of HRT3 and FDT perimetry for PSD (65.4 and 62.7 %, respectively) and for GPS (69.2 and 62.7 %, respectively) were similar, as were the positive predictive values (PSD 40.5 %, GPS 41.9 %). However, the 2 methods had only slight diagnostic agreement (κ = 0.112), and this was not significant (P = 0.281).

CONCLUSIONS

FDT perimetry and HRT3 had no significant diagnostic agreement. Thus, the results from both examinations should be considered when determining diagnosis of glaucoma.

Comparison of neuroretinal rim area measurements made by the Heidelberg Retina Tomograph I and the Heidelberg Retina Tomograph II

PURPOSE

To investigate the agreement between neuroretinal rim area (RA) measurements using the Heidelberg Retina Tomograph I (HRT Classic) and Heidelberg Retina Tomograph II (HRT II). To compare apparent RA changes in follow-up series of HRT II topographies when using either an HRT Classic or HRT II mean topography as baseline.

DESIGN

Cross-sectional study and "no-change," short time series study.

PARTICIPANTS

Forty-three ocular hypertensive and 31 primary open angle glaucoma subjects.

METHODS

Five HRT Classic and 5 HRT II examinations were acquired from 1 eye of each subject, across 2 visits within 6 weeks. For the cross-sectional study, follow-up RA measurements from HRT Classic and HRT II were compared, using the same HRT Classic mean topography as the baseline. The linear rates of RA change were compared in 2 short time series with either an HRT Classic or an HRT II mean topography as baseline, and 4 follow-up HRT II mean topographies. Intervals between topographies were arbitrarily set at 1 year for meaningful comparisons of rates. Rates of RA change over time were calculated by linear regression. Separate analyses were performed using 3 available reference planes (RP).

MAIN OUTCOME MEASURES

Global and sectoral RA measurements in HRT Classic and HRT II mean topographies; linear rates of RA change.

RESULTS

HRT Classic minus HRT II mean differences (95% limits of agreement) were 0.09 (-0.17, 0.35) mm, 0.09 (-0.13, 0.32) mm, and 0.11 (-0.24, 0.46) mm for the Moorfields, 320 µm, and standard RPs, respectively (P<0.001 for all RPs, Wilcoxon rank sum test). In the time series, the mean differences (95% limits of agreement) of RA rates of change (HRT Classic baseline minus HRT II baseline) were -0.01 (-0.06, 0.03) mm/y, -0.01 (-0.06, 0.04) mm/y, and -0.0 (-0.09, 0.05) mm/y using the Moorfields, 320 µm, and standard RPs, respectively.

CONCLUSION

Although HRT software is backward-compatible, follow-up RA measurements made in the same eye using HRT Classic and HRT II devices display statistically and clinically meaningful systematic differences when HRT Classic topographies are used as a baseline.

Factors affecting the sensitivity and specificity of the Heidelberg Retina Tomograph parameters to glaucomatous progression in disc photographs

PURPOSE

To evaluate the factors affecting the sensitivity and specificity of the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT) to glaucomatous progression in stereoscopic ONH photographs.

METHODS

The factors affecting the sensitivity and specificity of the vertical cup : disc ratio, the cup : disc area ratio, the cup volume, the rim area and a linear discriminant function to progression were analysed. These parameters were the best indicators of progression in a retrospective study of 476 eyes. The reference standard for progression was the masked evaluation of stereoscopic ONH photographs.

RESULTS

The factors having the most significant effect on the sensitivity and specificity of the stereometric ONH parameters were the reference height difference and the mean topography standard deviation (TSD), indicating image quality. Also, the change in the TSD and age showed consistent, but variably significant, influence on all parameters tested. The sensitivity and specificity improved when there was little change in the reference height, the image quality was good and stable, and the patients were younger. The sensitivity and specificity of the vertical cup : disc ratio was improved by a large disc area and high baseline cup : disc area ratio. The rim area showed a better sensitivity and specificity for progression with a small disc area and low baseline cup : disc area ratio.

CONCLUSION

The factors affecting the sensitivity and specificity of the stereometric ONH parameters to glaucomatous progression in disc photographs are essentially the same as those affecting the measurement variability of the HRT.

Heidelberg Retina Tomograph (HRT3) in population-based epidemiology: normative values and criteria for glaucomatous optic neuropathy

PURPOSE

To establish normative values for Heidelberg Retina Tomograph (HRT3) variables and to develop HRT3-based criteria for glaucomatous optic neuropathy for epidemiological research in a white population.

METHODS

Consecutive participants in the Rotterdam Study were examined with HRT and simultaneous stereoscopic fundus photography (ImageNet) in addition to other ophthalmic examinations including intraocular pressure (IOP) measurements and perimetry. Normative values for all HRT3 variables were determined in participants who met all the following criteria: no glaucomatous visual field loss (GVFL), an IOP of 21mmHg or less, no IOP lowering treatment, and a negative family history of glaucoma. Sensitivity was determined in participants with glaucomatous visual field loss at a fixed high specificity of 97.5% - a value commonly used in population-based epidemiology.

RESULTS

A total of 2516 participants were included in this study of whom 66 had glaucomatous visual field loss in at least one eye and 1680 fulfilled the criteria for contributing to the normative values. The HRT3 linear cup-disc ratio (LCDR) variable, adjusted for disc area, showed the highest sensitivity, 35%, at the required specificity of 97.5%. The 97.5th percentile of the LCDR was 0.67 for small discs (up to 1.5 mm(2)), 0.71 [corrected] for medium-sized discs and 0.76 [corrected] for large discs (above 2.0 mm(2)).The HRT3 Glaucoma Probability Score and previously published linear discriminant functions showed a lower sensitivity than LCDR at this specificity.

CONCLUSIONS

At the high specificity of 97.5% as is commonly used in population-based epidemiology, the sensitivity of the HRT3 is low - albeit not lower than that of the vertical cup-disc ratio as assessed with simultaneous stereoscopic fundus photography and analyzed with the ImageNet software. The LCDR variable, stratified for disc area, seems to be the most suitable variable to develop criteria for glaucomatous optic neuropathy for epidemiological purposes.

Role of imaging in glaucoma diagnosis and follow-up

The purpose of the review is to provide an update on the role of imaging devices in the diagnosis and follow-up of glaucoma with an emphasis on techniques for detecting glaucomatous progression and the newer spectral domain optical coherence tomography instruments. Imaging instruments provide objective quantitative measures of the optic disc and the retinal nerve fiber layer and are increasingly utilized in clinical practice. This review will summarize the recent enhancements in confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography with an emphasis on how to utilize these techniques to manage glaucoma patients and highlight the strengths and limitations of each technology. In addition, this review will briefly describe the sophisticated data analysis strategies that are now available to detect glaucomatous change overtime.

Predicting progression to glaucoma in ocular hypertensive patients

PURPOSE

To assess the ability of Heidelberg Retina Tomograph (HRT) Moorfields Regression Analysis (MRA) and Glaucoma Probability Score (GPS) classifications at baseline to predict glaucomatous progression in ocular hypertensive eyes.

METHODS

One hundred ninety-eight ocular hypertensive subjects underwent regular HRT and visual field (VF) testing from 1993 to 2001. HRT progression was assessed using linear regression of rim area/time. VF progression was assessed by pointwise linear regression of sensitivity/time. Subjects were classified as progressing or stable at the end of the study period. The relationship between baseline abnormal (outside normal limits combined with borderline classification) MRA and GPS classification and progression status was assessed by odds ratios (ORs).

RESULTS

An abnormal superotemporal MRA was the only classification found to be predictive of HRT progression in isolation (OR 3.05, 1.25-7.47). Abnormal global, superotemporal, superonasal, and temporal MRA classifications were all associated with significant ORs for predicting HRT or VF progression (OR range: 1.77-2.54). Abnormal GPS classifications were not predictive of disease behavior. Combined abnormal GPS and MRA classifications were associated with higher ORs than either classification in isolation.

CONCLUSIONS

Patients with an abnormal MRA and GPS classification at presentation may be at increased risk of HRT or VF change.

Comparison of the diagnostic capability of the Heidelberg Retina Tomographs 2 and 3 for glaucoma in the Indian population

PURPOSE

To compare the diagnostic capability of the Heidelberg Retina Tomograph (HRT) 2 and 3 (Heidelberg Engineering, GmBH, Dossenheim, Germany) for glaucoma in an Indian population.

DESIGN

Evaluation of a diagnostic technology.

PARTICIPANTS

Ninety-eight glaucoma subjects and 79 normal controls.

METHODS

All participants underwent imaging with HRT2. Heidelberg Retina Tomograph 2 examinations were exported to HRT3 software. The stereometric parameters of HRT2 and HRT3 were compared. The diagnostic capability of Moorfields Regression Analysis (MRA) in the HRT2, HRT3 with and without ethnicity correction, and Glaucoma Probability Score (GPS) of HRT3 were compared. Analysis was done with the borderline results of MRA and GPS considered as normal to derive the most specific criteria and as abnormal to derive the least specific criteria.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC).

RESULTS

On standard automated perimetry (SAP), the mean deviation (mean+/-standard deviation) of the glaucoma and normal groups were -7.3+/-6.7 dB and -0.4+/-1.1 dB, respectively (P<0.001). The AUC for the individual stereometric parameters of HRT2 were similar to that of HRT3. The sensitivity and specificity (most specific criteria) were 56.1% and 96.2%, respectively, for MRA of HRT2 and 56.1% and 91.1%, respectively, for MRA of HRT3. The sensitivity and specificity (least specific criteria) were 88.8% and 88.6%, respectively, for MRA of HRT2 and 70.4% and 81%, respectively, for MRA of HRT3. By using the Indian specific normative database of HRT3, the sensitivity and specificity were 37.8% and 97.5%, respectively, for the most specific criteria, and 55.1% and 89.9%, respectively, for the least specific criteria. Sensitivity and specificity of GPS were 86.7% and 68.3%, respectively, for the most specific criteria, and 93.9% and 39.2%, respectively, for the least specific criteria.

CONCLUSIONS

In this cohort, the diagnostic capability of HRT2 MRA was similar to that of HRT3 MRA; ethnicity correction did not improve results; GPS was more sensitive but less specific than MRA in diagnosing glaucoma.

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.