Detection of undiagnosed glaucoma by eye health professionals

Diagnosing glaucoma in primary eye care and the role of Artificial Intelligence applications for reducing the prevalence of undetected glaucoma in Australia

Glaucoma is the commonest cause of irreversible blindness worldwide, with over 70% of people affected remaining undiagnosed. Early detection is crucial for halting progressive visual impairment in glaucoma patients, as there is no cure available. This narrative review aims to: identify reasons for the significant under-diagnosis of glaucoma globally, particularly in Australia, elucidate the role of primary healthcare in glaucoma diagnosis using Australian healthcare as an example, and discuss how recent advances in artificial intelligence (AI) can be implemented to improve diagnostic outcomes. Glaucoma is a prevalent disease in ageing populations and can have improved visual outcomes through appropriate treatment, making it essential for general medical practice. In countries such as Australia, New Zealand, Canada, USA, and the UK, optometrists serve as the gatekeepers for primary eye care, and glaucoma detection often falls on their shoulders. However, there is significant variation in the capacity for glaucoma diagnosis among eye professionals. Automation with Artificial Intelligence (AI) analysis of optic nerve photos can help optometrists identify high-risk changes and mitigate the challenges of image interpretation rapidly and consistently. Despite its potential, there are significant barriers and challenges to address before AI can be deployed in primary healthcare settings, including external validation, high quality real-world implementation, protection of privacy and cybersecurity, and medico-legal implications. Overall, the incorporation of AI technology in primary healthcare has the potential to reduce the global prevalence of undiagnosed glaucoma cases by improving diagnostic accuracy and efficiency.

Price tag of glaucoma care is minor compared with the total direct and indirect costs of glaucoma: Results from nationwide survey and register data

BACKGROUND

The estimations of the economic burden of glaucoma have focused on comparing different treatment modalities; hence, the total direct and indirect costs of glaucoma at population level are not well known.

OBJECTIVE

To estimate the direct and indirect costs of glaucoma and its treatment in Finland.

METHODS

Economic and glaucoma data were collected from the cross-sectional nationwide Health 2000 health examination survey linked to multiple national registers, which allowed a 13-year follow-up between 1999-2011 among survey participants. Direct costs covered eye- and non-eye-related hospitalizations and outpatient visits, outpatient health care services, and travel costs among participants aged 30 years or older, adjusted for age and sex. Indirect costs covered premature retirement and productivity losses among participants aged 30-64 years. Glaucoma patients (n = 192) were compared with non-glaucomatous population (n = 6,952).

RESULTS

The annual additional total direct costs were EUR 2,660/glaucoma patient, EUR 1,769/glaucoma patient with medication, and EUR 3,979/operated glaucoma patient compared with persons without glaucoma. The respective additional total indirect costs were EUR 4,288, EUR 3,246, and EUR 12,902 per year. In total, the additional annual direct and indirect expenditures associated with glaucoma in Finland were EUR 202 million (0.86% of total expenditures of health care) and EUR 71 million (0.03% of the Finnish gross domestic product) arising mainly from non-eye-related hospitalizations and productivity losses, respectively.

CONCLUSION

Glaucoma is associated with an increased health care consumption mainly due to non-eye-related health care, which can be explained by the vision loss as well as increased number of co-morbidities among glaucoma patients. Therefore, glaucoma constitutes a major economic burden for the health care system and society, highlighting the importance of early glaucoma interventions. The difference in direct and indirect costs between glaucoma treatment groups is explained by the uneven distribution of co-morbidities.

Evaluating Discrepancies in Self-Reported Glaucoma and Electronic Health Records in the National Institutes of Health All of Us Database

PURPOSE

Patient understanding of glaucoma diagnosis is critical for disease management and it is unclear if there are racial/ethnic differences in this regard. The purpose of this study was to determine the level of agreement between glaucoma diagnosis by self-report and electronic health record (EHR) data using the National Institute of Health's "All of Us (AoU)" database and to examine the association between race/ethnicity and discordance of glaucoma diagnosis between self-report and EHR data.

DESIGN

Cross-sectional study.

PARTICIPANTS

Individuals in AoU who answered a survey question about glaucoma diagnosis and had EHR data availability.

METHODS

The agreement between self-reported glaucoma and EHR data was estimated using Cohen's κ coefficient. Multivariable logistic regression was performed, adjusting for age, sex, education level, income, and health care literacy, to examine the associations between race/ethnicity and discordance between self-reported glaucoma and EHR diagnosis.

MAIN OUTCOME MEASURES

Agreement between self-reported glaucoma and EHR diagnosis.

RESULTS

Of all 87 782 individuals, 1985 (2.26%) had both self-reported and EHR glaucoma, 81 781 (92.16%) had no glaucoma, 2022 (2.31%) individuals had EHR-only glaucoma, and 1994 (2.27%) had self-report-only glaucoma (Cohen's κ = 0.47). In the multivariable regression, Black or African American (adjusted odds ratio [aOR], 1.67; 95% confidence interval [CI], 1.40-1.98), Asian (aOR, 2.63; 95% CI, 1.97-3.44), and Hispanic or Latino (aOR, 1.63; 95% CI, 1.33-1.99) individuals were more likely to have EHR-only glaucoma than White individuals. Additionally, Black or African American (aOR, 2.30; 95% CI, 1.97-2.67) and Hispanic or Latino individuals (aOR,1.47; 95% CI, 1.21-1.79) were more likely to have self-report-only glaucoma compared with White individuals.

CONCLUSIONS

In the AoU database, we found that Black or African American and Hispanic or Latino individuals had higher odds of discordance between glaucoma diagnosis by self-report and EHR. Future studies are needed to examine the issues leading to this discordance, such as a lack of patient understanding regarding their diagnosis or a lack of culturally appropriate physician explanation/teaching.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Characteristics of a large, labeled dataset for the training of artificial intelligence for glaucoma screening with fundus photographs

Purpose

Significant visual impairment due to glaucoma is largely caused by the disease being detected too late.

Objective

To build a labeled data set for training artificial intelligence (AI) algorithms for glaucoma screening by fundus photography, to assess the accuracy of the graders, and to characterize the features of all eyes with referable glaucoma (RG).

Design

Cross-sectional study.

Subjects

Color fundus photographs (CFPs) of 113 893 eyes of 60 357 individuals were obtained from EyePACS, California, United States, from a population screening program for diabetic retinopathy.

Methods

Carefully selected graders (ophthalmologists and optometrists) graded the images. To qualify, they had to pass the European Optic Disc Assessment Trial optic disc assessment with ≥ 85% accuracy and 92% specificity. Of 90 candidates, 30 passed. Each image of the EyePACS set was then scored by varying random pairs of graders as "RG," "no referable glaucoma (NRG)," or "ungradable (UG)." In case of disagreement, a glaucoma specialist made the final grading. Referable glaucoma was scored if visual field damage was expected. In case of RG, graders were instructed to mark up to 10 relevant glaucomatous features.

Main Outcome Measures

Qualitative features in eyes with RG.

Results

The performance of each grader was monitored; if the sensitivity and specificity dropped below 80% and 95%, respectively (the final grade served as reference), they exited the study and their gradings were redone by other graders. In all, 20 graders qualified; their mean sensitivity and specificity (standard deviation [SD]) were 85.6% (5.7) and 96.1% (2.8), respectively. The 2 graders agreed in 92.45% of the images (Gwet's AC2, expressing the inter-rater reliability, was 0.917). Of all gradings, the sensitivity and specificity (95% confidence interval) were 86.0 (85.2-86.7)% and 96.4 (96.3-96.5)%, respectively. Of all gradable eyes (n = 111 183; 97.62%) the prevalence of RG was 4.38%. The most common features of RG were the appearance of the neuroretinal rim (NRR) inferiorly and superiorly.

Conclusions

A large data set of CFPs was put together of sufficient quality to develop AI screening solutions for glaucoma. The most common features of RG were the appearance of the NRR inferiorly and superiorly. Disc hemorrhages were a rare feature of RG.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Risk factors for previously undiagnosed primary open-angle glaucoma: the EPIC-Norfolk Eye Study

BACKGROUND AND AIM

Undiagnosed glaucoma is an invisible but important public health issue. At least half of glaucoma cases are estimated to be undiagnosed in western populations. The aim of this study is to examine risk factors for previously undiagnosed primary open-angle glaucoma (POAG).

DESIGN

Cross-sectional study within the European Prospective Investigation of Cancer-Norfolk Eye Study, a large-scale cohort study in the UK.

PARTICIPANTS

314 study participants with POAG in either eye.

METHODS

Logistic regression was used to examine associations with previously undiagnosed POAG compared with previously diagnosed POAG. The factors examined included sociodemographic, ocular, physical and economic factors that could be barriers to eye care access.

RESULTS

217 participants had previously diagnosed POAG and 107 participants were newly diagnosed with POAG during the study. After adjusting for covariables, the factors significantly associated with previously undiagnosed POAG were: a lower pretreatment intraocular pressure (IOP) (OR 0.71/mm Hg, 95% CI 0.63 to 0.80, p<0.0001), and to have reported no problems with their eyesight (OR 0.03, 95% CI 0.01 to 0.10, p<0.0001).

CONCLUSIONS

The risk factors for previously undiagnosed POAG identified in this study highlight the over-reliance on IOP level in glaucoma screening and the risk of missing glaucoma among lower IOP cases. It also suggests a role in improving glaucoma awareness in the community.

Development and Evaluation of a Rules-based Algorithm for Primary Open-Angle Glaucoma in the VA Million Veteran Program

The availability of electronic health record (EHR)-linked biobank data for research presents opportunities to better understand complex ocular diseases. Developing accurate computable phenotypes for ocular diseases for which gold standard diagnosis includes imaging remains inaccessible in most biobank-linked EHRs. The objective of this study was to develop and validate a computable phenotype to identify primary open-angle glaucoma (POAG) through accessing the Department of Veterans Affairs (VA) Computerized Patient Record System (CPRS) and Million Veteran Program (MVP) biobank. Accessing CPRS clinical ophthalmology data from VA Medical Center Eye Clinic (VAMCEC) patients, we developed and iteratively refined POAG case and control algorithms based on clinical, prescription, and structured diagnosis data (ICD-CM codes). Refinement was performed via detailed chart review, initially at a single VAMCEC (n = 200) and validated at two additional VAMCECs (n = 100 each). Positive and negative predictive values (PPV, NPV) were computed as the proportion of CPRS patients correctly classified with POAG or without POAG, respectively, by the algorithms, validated by ophthalmologists and optometrists with access to gold-standard clinical diagnosis data. The final algorithms performed better than previously reported approaches in assuring the accuracy and reproducibility of POAG classification (PPV >83% and NPV >97%) with consistent performance in Black or African American and in White Veterans. Applied to the MVP to identify cases and controls, genetic analysis of a known POAG-associated locus further validated the algorithms. We conclude that ours is a viable approach to use combined EHR-genetic data to study patients with complex diseases that require imaging confirmation.

The performance of iPad-based noise-field perimeter versus Humphrey Field Analyser in detecting glaucomatous visual field loss

BACKGROUND

To conduct a preliminary evaluation of the feasibility of visual field fast (VFF), a free iPad-based noise-field perimeter, in detecting glaucomatous scotomas versus the clinical-standard Humphrey visual field (HVF) test. VFF confronts subjects with a screen of flickering stimulus, allowing the immediate perception of scotomas.

METHODS

This was a cross-sectional observational study of 66 glaucoma patients (66 eyes) and 30 healthy controls (30 eyes). All patients had no other visual field disorders. VFF was compared against HVF in terms of whole field and quadrants for the following: (1) correspondence in scotoma detection. (2) Agreement and correlation of the scotoma size (percentage of abnormal visual field area). (3) Test duration. Other domains tested included: (1) correlation of VFF scotoma area with the severity of visual field loss on HVF (mean deviation, MD; visual field index, VFI). (2) Repeatability of VFF. (3) Patient descriptors of scotomas.

RESULTS

Using HVF pattern deviation plot as a reference, VFF detected 52/57 (91.2%) of glaucoma subjects with 1 false-positive (control) (kappa = 0.86). 146/184 (79.3%) of abnormal quadrants (visual field defect present) were localized and 23/157 (14.6%) healthy quadrants were falsely identified as abnormal (kappa = 0.61). VFF underestimated scotoma area as compared to HVF (21.0% versus 44.0%, p < 0.01) but correlated positively (r = 0.268, p = 0.044) with HVF area and negatively with VFI (r = -0.340, p = 0.01) and MD (r = -0.398, p < 0.01). Using HVF total deviation plot as reference, VFF's glaucoma detection rate remained unchanged (kappa = 0.86) with similar quadrant detection (kappa = 0.68). However, a greater underestimation of scotoma area was observed (21.0% versus 85.4%, p < 0.01). VFF's quantitative repeatability was excellent for whole field (intraclass correlation coefficient, ICC: 0.96; p < 0.0001) and quadrants (ICC: 0.82-0.96; all p < 0.001). Qualitatively, 35/37 (94.6%) of subjects reported reduced luminance and flicker in scotomas, with similar morphologies on retests. VFF is faster than HVF SITA-Standard in glaucoma (3.60 ± 1.85 min versus 6.92 ± 1.12 min, p < 0.01) and control (1.12 ± 0.486 min versus 5.16 ± 0.727 min, p < 0.01).

CONCLUSION

This early model of VFF accurately detected scotomas with high repeatability. However, its accuracy in localizing and quantifying the scotoma can be improved. Considering its portability and cost-effectiveness, VFF demonstrated potential as a general screening tool for moderate-to-severe glaucoma.

Erroneous assumption of ocular hypertension in patients with elevated intraocular pressure

Purpose:

To determine the proportion of erroneously assumed ocular hypertension (OHT) among referred patients of elevated intraocular pressure (IOP) seen in glaucoma clinic of a teaching hospital in Northern India.

Methods:

Retrospective review of case records of referred, diagnosed patients of OHT or unspecified glaucoma seen between January 2019 and March 2020. Using an algorithmic clinical approach, including gonioscopy, Goldmann applanation tonometry (GAT), and pachymetry, underlying cause for elevated-IOP was amended and proportion of erroneously assumed OHT was calculated.

Results:

Of 276 patients diagnosed either as OHT or unspecified glaucoma before being seen at our glaucoma clinic, 44 (16%) had IOP within normal range (10–21 mmHg) on GAT. In 97 (35%) cases elevated-IOP was associated with angle closure. The central corneal thickness (CCT) was >550 μm in 39 (14%) patients with elevated-IOP. The proportion of erroneously assumed OHT was 70% in this study.

Conclusion:

The elevated-IOP does not imply with OHT unless evident through comprehensive clinical examination and appropriate investigations.

Screening for Glaucomatous Visual Field Defects in Rural Australia with an iPad

Aim and objective

Developing improved methods for early detection of visual field defects is pivotal to reducing glaucoma-related vision loss. The Melbourne Rapid Fields screening module (MRF-S) is an iPad-based test, which allows suprathreshold screening with zone-based analysis to rapidly assess the risk of manifest glaucoma. The versatility of MRF-S has potential utility in rural areas and during infectious pandemics. This study evaluates the utility of MRF-S for detecting field defects in non-metropolitan settings.

Materials and methods

This was a prospective, multicenter, cross-sectional validation study. Two hundred and fifty-two eyes of 142 participants were recruited from rural sites through two outreach eye services in Australia. Participants were tested using MRF-S and compared with a reference standard; either Zeiss Humphrey Field Analyzer or Haag-Streit Octopus performed at the same visit. Standardized questionnaires were used to assess user acceptability. Major outcome measures were the area under the curve (AUC) for detecting mild and moderate field defects defined by the reference tests, along with corresponding performance characteristics (sensitivity, specificity).

Results

The mean test duration for MRF-S was 1.88 minutes compared with 5.92 minutes for reference tests. The AUCs for mild and moderate field defects were 0.81 [95% confidence interval (CI): 0.75–0.87] and 0.87 (95% CI: 0.83–0.92), respectively, indicating very good diagnostic accuracy. Using a risk criterion of 55%, MRF-S identified moderate field defects with a sensitivity and specificity of 88.4 and 81.0%, respectively.

Conclusion and clinical significance

The MRF-S iPad module can identify patients with mild and moderate field defects while delivering favorable user acceptability and short test duration. This has potential application within rural locations and amidst infectious pandemics.

How to cite this article

Chia MA, Trang E, Agar A, et al. Screening for Glaucomatous Visual Field Defects in Rural Australia with an iPad. J Curr Glaucoma Pract 2021;15(3):125–131.

Differentiating Diagnosed and Undiagnosed Primary Angle-Closure Glaucoma and Open-Angle Glaucoma: A Population-Based Study

PURPOSE

To study and compare factors contributing to the differentiation between diagnosed and undiagnosed primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG) in the same population.

DESIGN

Population-based survey.

PARTICIPANTS

All residents 40 years of age and older in Kumejima, Japan.

METHODS

Primary angle-closure glaucoma and POAG were diagnosed according to the criteria of the International Society of Geographical and Epidemiological Ophthalmology. Factors contributing significantly to the differentiation between diagnosed and undiagnosed PACG and POAG were selected from various systemic, ocular, visual function, and fundus planimetric parameters using multivariate logistic regression analysis and were compared between the two diseases.

MAIN OUTCOME MEASURES

Factors contributing significantly to the differentiation between diagnosed and undiagnosed PACG and POAG.

RESULTS

The prevalence rates of PACG and POAG were 2.2% and 4.0%, respectively. A greater proportion of patients with PACG (34.1%) received a diagnosis previously compared with patients with POAG (17.2%; P = 0.004). Worse mean deviation on visual field (VF) testing (odds ratio, 0.869; 95% confidence interval, 0.788-0.959; P = 0.006) and the presence of signs suggestive of previous acute angle closure (odds ratio, 4.35; range, 1.66-11.36; P = 0.003) contributed to a established diagnosis of PACG at the time of screening. A greater vertical cup-to-disc ratio (3.74; range, 1.38-10.17; P = 0.012) contributed with marginal significance to an established diagnosis of POAG at the time of screening.

CONCLUSIONS

Primary angle-closure glaucoma was more likely to have been diagnosed previously than POAG during a screening examination. Examination of the anterior segment and VF may contribute more to the detection of PACG, and disc examination may contribute more to the detection of POAG.

Vision Impairment Provides New Insight Into Self-Motion Perception

Purpose

Leading causes of irreversible blindness such as age-related macular degeneration (AMD) and glaucoma can, respectively, lead to central or peripheral vision loss. The ability of sufferers to process visual motion information can be impacted even during early stages of eye disease. We used head-mounted display virtual reality as a tool to better understand how vision changes caused by eye diseases directly affect the processing of visual information critical for self-motion perception.

Methods

Participants with intermediate AMD or early manifest glaucoma with near-normal visual acuities and visual fields were recruited for this study. We examined their experiences of self-motion in depth (linear vection), spatial presence, and cybersickness when viewing radially expanding patterns of optic flow simulating different speeds of self-motion in depth. Viewing was performed with the head stationary (passive condition) or while making lateral-sway head movements (active conditions).

Results

Participants with AMD (i.e., central visual field loss) were found to have greater vection strength and spatial presence, compared to participants with normal visual fields. However, participants with glaucoma (i.e., peripheral visual field loss) were found to have lower vection strength and spatial presence, compared to participants with normal visual fields. Both AMD and glaucoma groups reported reduced severity in cybersickness compared to healthy normals.

Conclusions

These findings strongly support the view that perceived self-motion is differentially influenced by peripheral versus central vision loss, and that patients with different visual field defects are oppositely biased when processing visual cues to self-motion perception.

The Global Extent of Undetected Glaucoma in Adults: A Systematic Review and Meta-analysis

TOPIC

Glaucoma is the leading cause of irreversible blindness, despite having good prognosis with early treatment. We evaluated the global extent of undetected glaucoma and the factors associated with it in this systematic review and meta-analysis.

CLINICAL RELEVANCE

Undetected glaucoma increases the risk of vision impairment, which leads to detrimental effects on the quality-of-life and socioeconomic well-being of those affected. Detailed information on the extent and factors associated with undetected glaucoma aid in the development of public health interventions.

METHODS

We conducted a systematic review and meta-analysis of population-based studies published between January 1, 1990, and June 1, 2020. Article search was conducted in online databases (PubMED, Web-of-Science), grey literatures (OpenGrey), and nongovernment organization reports. Our outcome measure was the proportion of glaucoma cases that were undetected previously. Manifest glaucoma included any form of glaucoma reported in the original studies and may include primary open-angle glaucoma (POAG), primary angle-closure-glaucoma, secondary glaucoma, or a combination thereof. Undetected glaucoma was defined as glaucoma cases that were undetected prior to diagnosis in the respective study. Random-effect meta-analysis was used to estimate the pooled proportion of undetected glaucoma. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Meta-analysis of Observational Studies in Epidemiology guidelines in our study.

RESULTS

We identified 61 articles from 55 population-based studies (n = 189 359 participants; n = 6949 manifest glaucoma). Globally, more than half of all glaucoma cases were undetected previously on average in each geographical region. Africa (odds ratio [OR], 12.70; 95% confidence interval [CI], 4.91-32.86) and Asia (OR, 3.41; 95% CI, 1.63-7.16) showed higher odds of undetected glaucoma as compared with Europe. Countries with low Human Development Index (HDI; <0.55) showed a higher proportion of undetected manifest glaucoma as compared with countries of medium to very high HDI (≥0.55; all P < 0.001). In 2020, 43.78 million POAG cases were projected to be undetected, of which 76.7% were in Africa and Asia.

DISCUSSION

Undetected glaucoma is highly prevalent across diverse communities worldwide and more common in Africa and Asia. Strategies to improve detection are needed to prevent excess visual disability and blindness resulting from glaucoma.

The Prevalence of Undiagnosed Age-Related Sight-Threatening Diseases in Self-Proclaimed Healthy Individuals

Background

Age-related conditions such as glaucoma, age-related macular degeneration, diabetic retinopathy, and cataract have become the major cause of visual impairment and blindness in high-income countries. The aim of the current study is to investigate the prevalence of these eye diseases in a cohort of self-proclaimed healthy elderly and thus get a rough estimation of the prevalence of undiagnosed age-related eye conditions in the Belgian population.

Methods

Individuals aged 55 and older without ophthalmological complaints were asked to fill in a general medical questionnaire and underwent an ophthalmological examination, which included a biomicroscopic examination, intraocular pressure measurement, axial length measurement, and acquisition of fundus pictures and optical coherence tomography scans. Information regarding follow-up was collected in those who received the advice of referral to an ophthalmologist or the advice to have more frequent follow-up visits, based on their study evaluation.

Results

The cohort included 102 people and comprised 46% men (median age 70 years, range 57–85 years). Referral for additional examinations was made in 26 participants (25%). The advice to have more regular follow-up ophthalmologist visits was given to nine additional participants (9%). No significant correlations between baseline characteristics and the need for referral could be identified. Follow-up information was available for 25 out of 26 referred volunteers. Out of these, four underwent a therapeutic intervention based on study referral, up until 18 months after study participation. All four interventions took place in the age group 65–74 years.

Conclusions

This study shows that, even in an elderly population with self-proclaimed healthy eyes and good general health, a significant proportion of subjects showed ocular findings that need regular follow-up and/or intervention. The frequency of prior ophthalmological examinations does not seem to be relevant to this proportion, meaning that everyone above 55 years old needs a routine ophthalmological evaluation.

Prevalence of glaucoma in the Northern Finland Birth Cohort Eye Study

PURPOSE

To report the prevalence of glaucoma in the Northern Finland Birth Cohort (NFBC) Eye Study.

METHODS

Subjects of the population-based Northern Finland 1966 Birth Cohort (NFBC), aged 45-49 years at the time of the field examination, were randomized to eye screening (50%) and control (50%) groups. The eye examination protocol included best corrected visual acuity (BCVA), measurements of intraocular pressure and central corneal thickness, Humphrey 24-2 perimetry, stereoscopic optic nerve head (ONH) and retinal nerve fibre layer (RNFL) photography and imaging with optical coherence tomography (OCT), scanning laser polarimetry (GDx) and scanning laser ophthalmoscopy (HRT). The diagnosis of glaucoma was made by two independent general ophthalmologists and three independent glaucoma experts based on the evaluation of the ONH and RNFL photographs and the visual fields.

RESULTS

Totally, 10 321 subjects of the NFBC main study were alive in Finland in 2011, and they were randomized to the NFBC Eye Study group (n = 5155) and the control group (n = 5166). Of the randomized subjects, 3039 of 5155 (59%) responded and had sufficient data for the study. Glaucoma was suspected in 172 subjects (5.7%) at the first phase of the evaluation protocol. The interobserver agreement between two screening ophthalmologists was moderately good (kappa value 0.54 [95% confidence intervals (CI) 0.46-0.61]). Finally, definite glaucoma was found in 33 subjects (1.1% [95% CI 0.8-1.5]).

CONCLUSION

The study provides up-to-date information on the prevalence of glaucoma in a middle-aged Caucasian population in Finland. The baseline data reported here allows the evaluation of the cost-effectiveness of screening later on.

Overdiagnosis of open-angle glaucoma in the general population: the Thessaloniki Eye Study

PURPOSE

To assess the overdiagnosis of open-angle glaucoma (OAG) and to investigate associated factors.

METHODS

This was a cross-sectional, population-based study of an urban Caucasian population in northern Greece. Randomly selected subjects ≥60 years (n = 2554) participated in the Thessaloniki Eye Study. The definition of OAG required the presence of structural and functional damage, irrespective of intraocular pressure (IOP). Non-OAG subjects were classified as overdiagnosed with OAG if they had reported at least one of the following (self-reported glaucoma): (i) prior diagnosis of glaucoma, (ii) prior laser for glaucoma, (iii) prior glaucoma surgery. Factors associated with the overdiagnosis of OAG were investigated using a logistic regression model.

RESULTS

Of 57 (2.2%) subjects with self-reported glaucoma, 34 (60%) were overdiagnosed with OAG, corresponding to a prevalence of 1.3% (34/2554). In a logistic regression model among non-OAG subjects, worse visual acuity (VA) (20/200 or worse versus 20/25 or better; odds ratio (OR) = 4.30, 95% Confidence Intervals (CI), 1.13-16.35), family history of glaucoma (OR = 8.69, 95% CI, 2.83-26.67) and history of cataract surgery (OR = 11.50, 95% CI, 3.85-34.36) were statistically significantly associated with the overdiagnosis of OAG. Age, sex, higher IOP, higher vertical cup-to-disc ratio and pseudoexfoliation were not statistically significant.

CONCLUSION

The overdiagnosis of OAG was substantial in this elderly, Caucasian population. The overdiagnosis of glaucoma has not been previously addressed in population-based studies and needs to be further explored.

Design of optical system for binocular fundus camera

A non-mydriasis optical system for binocular fundus camera has been designed in this paper. It can capture two images of the same fundus retinal region from different angles at the same time, and can be used to achieve three-dimensional reconstruction of fundus. It is composed of imaging system and illumination system. In imaging system, Gullstrand Le Grand eye model is used to simulate normal human eye, and Schematic eye model is used to test the influence of ametropia in human eye on imaging quality. Annular aperture and black dot board are added into illumination system, so that the illumination system can eliminate stray light produced by corneal-reflected light and omentoscopic lens. Simulation results show that MTF of each visual field at the cut-off frequency of 90lp/mm is greater than 0.2, system distortion value is -2.7%, field curvature is less than 0.1 mm, radius of Airy disc is 3.25um. This system has a strong ability of chromatic aberration correction and focusing, and can image clearly for human fundus in which the range of diopters is from -10 D to +6 D(1 D = 1 m^-1).

Clinical Utility of Optical Coherence Tomography in Glaucoma

Optical coherence tomography (OCT) has established itself as the dominant imaging modality in the management of glaucoma and retinal diseases, providing high-resolution visualization of ocular microstructures and objective quantification of tissue thickness and change. This article reviews the history of OCT imaging with a specific focus on glaucoma. We examine the clinical utility of OCT with respect to diagnosis and progression monitoring, with additional emphasis on advances in OCT technology that continue to facilitate glaucoma research and inform clinical management strategies.

Comparison of Peristat Online Perimetry with the Humphrey Perimetry in a Clinic-Based Setting

Purpose

We determined the receiver operating characteristic (ROC) curves for Peristat online perimetry at detecting varying degrees of glaucoma and the correlation between Peristat online perimetry and Humphrey visual field.

Methods

A prospective, comparative study of Peristat online perimetry (an achromatic static computer threshold testing program) and Humphrey visual field (HVF) 24-2 SITA standard testing was performed by 63 glaucoma patients and 30 healthy controls in random order. The number of total adjacent abnormal test points were identified for each test, and compared with Spearman correlation. Receive operating characteristic curves were generated for Peristat online perimetry detection of mild and moderate-severe glaucoma patients using contrast sensitivity thresholds of −16.7, −21.7, and −26.7 dB.

Results

The area under the ROC curve for glaucoma detection ranged from 0.77 to 0.81 for mild disease (mean deviation [MD], >−6 dB on HVF) and 0.85 to 0.87 for moderate to severe disease (MD, <−6 dB on HVF) depending on contrast threshold. Peristat online perimetry and Humphrey visual field abnormal points were highly correlated with Spearman rank correlations ranging from 0.55 to 0.77 (all P < 0.001).

Conclusions

Peristat online perimetry exhibits a reasonable ROC curve without specialized equipment and exhibited significant correlation with the conventional 24° Humphrey visual field test.

Translational Relevance

Low cost widely available internet-based visual fields may complement traditional office-based visual field testing.

Spectral-Domain Optical Coherence Tomography for Glaucoma Diagnosis

Identification of structural damage to the optic nerve and retinal nerve fiber layer (RNFL) is an essential component of diagnosis and management of glaucoma. The introduction of spectral-domain OCT (SD-OCT) has allowed objective quantification of damage to these structures with unprecedented resolution. In addition, recent attention has been directed towards imaging the macular area for quantifying loss of neural tissue caused by the disease. Many studies have evaluated and compared the diagnostic accuracies of a variety of parameters that can be obtained from imaging these areas of the ocular fundus. In this article, we critically review the existing literature evaluating the diagnostic accuracy of SD-OCT in glaucoma and we discuss issues related to how SD-OCT results should be incorporated into clinical practice.

Central retinal artery resistive index and optical coherence tomography in assessment of glaucoma progression

AIM

To assess the relation between central retinal artery (CRA) resistive index (RI) and retinal nerve fiber thickness measured by optical coherence tomography (OCT) in assessment of disease progress in cases of open angle glaucoma.

METHODS

Twenty-three patients with diagnosed open angle glaucoma were included in this study. They were examined by colored duplex ultrasonography of CRA with estimation of RI of CRA and ophthalmic artery (OA) with estimation of CRA/OA RI ratio as well as OCT measurement of the average retinal nerve fiber layer (RNFL) thickness in order to assess the disease progress.

RESULTS

There was strong inverse relation between the increased RI in CRA as well as the increased CRA/OA RI ratio and the decrease in average RNFL thickness in cases of open angle glaucoma.

CONCLUSION

Assessment of CRA RI can indirectly assess the vascular changes associated with glaucoma and can assess the degree of retinal atrophy helping in evaluating prognosis thus guiding the choice of treatment.

Clinical model assisting with the collaborative care of glaucoma patients and suspects

BACKGROUND

Optimizing patient management will reduce unnecessary vision loss in glaucoma through early detection. One method is the introduction of collaborative care schemes between optometrists and ophthalmologists.

DESIGN

We conducted a retrospective study to evaluate the impact of the Centre for Eye Health (CFEH) on glaucoma patient outcomes and management in primary optometric care.

PARTICIPANTS

Patients referred to CFEH by optometrists for a glaucoma assessment were eligible for this study if written consent was provided (500 participants were randomly chosen).

METHODS

Clinical data were classified according to disease risk and implemented patient care and analysed against the original diagnosis and patient parameters, followed by statistical analysis.

MAIN OUTCOME MEASURES

Two main parameters were evaluated; suitable referral of patients for glaucoma condition assessment and appropriate implementation of follow-up care.

RESULTS

The majority of patients referred for glaucoma assessment (86.2%) were classified as glaucoma suspects or likely to have glaucoma, indicating suitable referral of patients for a CFEH evaluation. Further, the involvement of CFEH resulted in a false positive rate of 7.8% for those patients who proceeded to ophthalmological care. However, long-term optometric patient care was not maintained for up to a third of primarily lower risk patients.

CONCLUSIONS

The investigated collaborative eye health-care model led to a substantial improvement in appropriate referrals of glaucoma patients to ophthalmologists and could be suitable for optimizing patient care and utilization of resources. Improvement in follow-up of patients by optometrists is required to minimize inappropriately discontinued patient care.

Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror

We developed an ultrahigh speed, handheld swept source optical coherence tomography (SS-OCT) ophthalmic instrument using a 2D MEMS mirror. A vertical cavity surface-emitting laser (VCSEL) operating at 1060 nm center wavelength yielded a 350 kHz axial scan rate and 10 µm axial resolution in tissue. The long coherence length of the VCSEL enabled a 3.08 mm imaging range with minimal sensitivity roll-off in tissue. Two different designs with identical optical components were tested to evaluate handheld OCT ergonomics. An iris camera aided in alignment of the OCT beam through the pupil and a manual fixation light selected the imaging region on the retina. Volumetric and high definition scans were obtained from 5 undilated normal subjects. Volumetric OCT data was acquired by scanning the 2.4 mm diameter 2D MEMS mirror sinusoidally in the fast direction and linearly in the orthogonal slow direction. A second volumetric sinusoidal scan was obtained in the orthogonal direction and the two volumes were processed with a software algorithm to generate a merged motion-corrected volume. Motion-corrected standard 6 x 6 mm(2) and wide field 10 x 10 mm(2) volumetric OCT data were generated using two volumetric scans, each obtained in 1.4 seconds. High definition 10 mm and 6 mm B-scans were obtained by averaging and registering 25 B-scans obtained over the same position in 0.57 seconds. One of the advantages of volumetric OCT data is the generation of en face OCT images with arbitrary cross sectional B-scans registered to fundus features. This technology should enable screening applications to identify early retinal disease, before irreversible vision impairment or loss occurs. Handheld OCT technology also promises to enable applications in a wide range of settings outside of the traditional ophthalmology or optometry clinics including pediatrics, intraoperative, primary care, developing countries, and military medicine.

Prevalence of end-of-life visual impairment in patients followed for glaucoma

PURPOSE

To assess the prevalence of end-of-life visual impairment in patients followed for glaucoma.

METHODS

Data of 122 patients followed for glaucoma who had died between July 2008 and July 2010 and who had visited the ophthalmology outpatient department of a large non-academic Dutch hospital were collected from the medical files. Sixty-one patients had open-angle glaucoma (OAG), and 61 patients were suspect for glaucoma or had ocular hypertension (OHT). Visual impairment was defined as a mean deviation value <-15 dB or a Snellen visual acuity <0.3 (20/60) of the better eye. We determined the number of patients with visual impairment on the last patient visit before death and investigated its main explanations.

RESULTS

Overall, the mean age at death was 81.8 years after a mean follow-up period of 9.2 years. Seventy-three per cent of all patients had their last visit in the year preceding death. In OAG, 16 patients (26%) had an end-of-life visual impairment. In nine patients (15%), this was caused by glaucoma. Eight of them had substantial visual loss at the initial visit. Six (10%) impaired OAG cases were mainly explained by ocular comorbidity, and there was an equal contribution of comorbidity and glaucoma in one case. Five glaucoma suspects or patients with OHT (8%) were visually impaired at death and these were all caused by ocular comorbidity.

CONCLUSION

The prevalence of end-of-life visual impairment is considerable in patients with OAG. Substantial visual loss at baseline is an important contributing factor. In glaucoma suspects or patients with OHT, the prevalence is lower and can be attributed to ocular comorbidity.

Glaucoma screening: current perspectives and future directions

INTRODUCTION

Glaucoma is an optic neuropathy with characteristic progressive optic nerve degeneration. Early detection and treatment may prevent blindness; however, the value of glaucoma screening has been debated.

METHODS

Articles pertaining to glaucoma screening were reviewed.

RESULTS

In reviewing the glaucoma literature, there is a lack of a sensitive and specific screening test and concerns over cost-effectiveness. Methods of screening include population-based screening and opportunistic case finding, which both have advantages and disadvantages.

CONCLUSIONS

Additional research is needed to better understand glaucoma progression as well as to identify improved screening tests. Consideration must be given not only to the feasibility of performing a glaucoma screening, but also to the follow-up and long-term care for glaucoma patients.

Prevalence and severity of undetected manifest glaucoma: results from the early manifest glaucoma trial screening

PURPOSE

To estimate the prevalence and severity of undetected glaucoma in the population.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 32 918 subjects aged 55 to 79 years from Malmö, Sweden, who were screened between 1992 and 1997. All subjects in the screened age groups living in the catchment area, and for whom there were no recent records at the Malmö University Hospital Ophthalmology department, were invited. The main purpose of the screening was to recruit subjects for the Early Manifest Glaucoma Trial.

METHODS

We registered the age, sex, and amount of visual field loss in subjects with previously undiagnosed glaucoma identified at the screening. The disease was categorized into 5 stages based on perimetric mean deviation values.

MAIN OUTCOME MEASURES

Prevalence of undetected glaucoma at various disease stages in different age groups expressed as percentages.

RESULTS

Among the screened subjects, who were 77.5% of all invited subjects, a total of 406 subjects (1.23%) were identified with previously undetected glaucoma. Prevalence increased with age, from 0.55% at 55 to 59 years to 2.73% at 75 to 79 years. Unilateral disease accounted for 66% of all cases. Extent of visual field loss was similar in all age groups from 60 years and more. Most eyes had early (35%) or moderate (31%) glaucomatous visual field defects, but 134 subjects (33%) had advanced visual field loss in at least 1 eye. No subject was blind in both eyes, but 3.4% of the newly diagnosed patients were unilaterally blind because of glaucoma.

CONCLUSIONS

Prevalence of undetected glaucoma increased with age, whereas disease severity did not increase in subjects older than 60 years of age. One third of subjects with previously undetected glaucoma had advanced or later-stage disease in at least 1 eye. Unilaterally blind subjects were present in all age groups.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Glaucoma costs in Denmark in treatment naive patients

PURPOSE

To describe the costs and providers of glaucoma treatment in Denmark.

METHODS

Analyses were based on National Register data. Glaucoma/OHT patients were identified by their first prescription for glaucoma medication (ATC-codes) in the Danish Register of Medicinal Product Statistics 2002-2007. Patients had used no glaucoma medication for 6 months. Data for 2007 were sampled cross-sectionally for a budgetary analysis of glaucoma (ICD10 code) medication and services consumed in the primary and secondary health care services. Patients were categorized according to their number of treatment changes.

RESULTS

The Danish annual incidence rate of glaucoma was estimated at 1.2 per 1000 adult persons. Thirty-seven per cent of patients (men 44%, mean age 68 years; women 56%, mean age 71 years) persisted with their initial treatment regimen, 21% had changed to a second regimen, and 43% had experienced ≥ 3 regimens. Treatment costs increased with the number of sequential regimens. Annual glaucoma costs (health care sector perspective) were €305 for patients under their initial regimen, increasing to €740 with ≥ 3 regimens. Drug costs accounted for 57% of total cost.

CONCLUSIONS

Drugs represented the major cost of glaucoma, and those costs increased, obviously, with the number of treatment changes.

Glaucoma diagnostics

This thesis addresses several aspects of glaucoma diagnostics from both a clinical and a screening perspective. New instruments for diagnosing glaucoma have been developed over the past years, but little information is available regarding their performance as screening methods and their usefulness in ordinary clinical practice. PURPOSE OF THE RESEARCH UNDERLYING THIS THESIS:  The objectives of this research were as follows: to compare the accuracy of results of analysis of the optic nerve head (ONH) achieved by computerized imaging using the Heidelberg Retina Tomograph (HRT) and by subjective assessment performed by physicians with different degrees of experience of glaucoma (paper III); to evaluate the effect of a continuous medical education (CME) lecture on subjective assessment of the ONH for diagnosis of glaucoma (paper II); to investigate subjective assessment of perimetric test results by physicians with varying knowledge of glaucoma with a trained artificial neural network (ANN) and to compare the certainty of the classifications (paper IV); and to compare the diagnostic performance of time-domain Stratus optical coherence tomography (OCT) with that of spectral-domain Cirrus OCT (paper I), frequency doubling technology (FDT) screening perimetry and scanning laser polarimetry with the GDx variable corneal compensator (VCC) in a random population-based sample and in patients with glaucoma of varying disease severity.

METHODS AND RESULTS

  In evaluation of the ONH, use of the HRT statistical tools, Moorfields regression analysis (MRA) and the Glaucoma Probability Score (GPS) was compared with subjective assessment performed by 45 physicians. Optic nerve head images and photographs from 138 healthy and 97 glaucoma subjects were included. The sensitivity of MRA was higher (87-94%) than that of the average physician (62-82%), considerably greater than that of ophthalmologists with subspecialties other than glaucoma (53-77%) and non-significantly better than that of glaucoma experts (72-88%). Sensitivity achieved by GPS (79-93%) was also greater than that of the average physician. MRA correctly classified all eyes with advanced glaucomatous visual field defects, a result that was not achieved by GPS or even by the glaucoma experts. In eyes with small discs, MRA sensitivity (88%) was comparable with that of glaucoma experts (85%) and much better than that of GPS (50%). Also, the group comprising all physicians provided specificity (75-92%) similar to that of both MRA (69 - 86%) and GPS (72-94%) (Andersson et al. 2011a). A 1-hr CME lecture on ONH assessment led to a significant improvement in sensitivity (from 70% to 80%) and a significant decrease in uncertain assessments (from 22% to 13%), whereas specificity remained unchanged (68%) (Andersson et al. 2011b). A rise in sensitivity was seen in all subgroups of physicians, including glaucoma experts. Thirty physicians assessing standard automated perimetry (SAP) test results as Humphrey Field Analyzer single-field analysis printouts with full StatPac information from 99 patients with glaucoma and 66 healthy subjects were compared with a trained ANN regarding diagnostic performance. ANN reached significantly higher sensitivity (93%) than the average physician (83%), whereas specificity was similar for these two groups (91% and 90%, respectively). Diagnostic accuracy was similar among the different groups of physicians and seemingly rather independent of experience. Sensitivity ranged from 82% in the subgroup of other subspecialists to 87% in the glaucoma expert group, and specificity ranged from 88% among general ophthalmologists to 91% for glaucoma experts. The ANN attained certainty of classification that was in parity with that provided by the glaucoma experts and did not make any completely incorrect classifications of the visual fields (i.e. erroneous classifications were in the borderline zone) (Andersson et al. 2012). From a population-based randomly selected sample (n=308) of older subjects (aged ≥ 50 years) living in southern Sweden, 170 subjects underwent a comprehensive examination that included Stratus OCT, Cirrus OCT, an FDT screening programme and the GDx VCC. The same test protocol was applied to 138 randomized clinical patients with different stages of glaucoma. In the population-based sample, both Stratus and Cirrus OCT showed high diagnostic accuracy with area under the receiver-operating curve (aROC) values close to 1.0 (Bengtsson et al. 2012). Both OCT instruments correctly classified all of the clinical glaucoma patients with advanced disease. FDT screening showed high sensitivity (91%) but erroneously gave normal test results for some eyes with advanced disease. GDx VCC had lower sensitivity (73-92%) and also led to a large proportion of examinations with an atypical retardation pattern that is known to affect the diagnostic efficiency of this instrument.

CONCLUSIONS

  The HRT MRA performed better than most physicians and was consistent with the glaucoma experts. These results suggest that MRA can be a valuable tool for diagnosing glaucoma in ordinary practice, particularly when only a few glaucoma experts are available. Even though MRA provided 100% sensitivity in eyes with advanced glaucoma, it probably does not offer sufficient specificity to make it suitable as a screening method. Continuing medical education on ONH analysis had a small, but positive effect on diagnostic accuracy for glaucoma. An ANN trained to classify visual fields seemed to perform at least as well as most of the participating physicians, whose performances were remarkably similar regardless of their level of experience. This indicates that available tools for interpreting SAP findings are helpful in assessments of visual field test results. However, SAP is associated with learning effects (Heijl et al. 1989) that may entail low specificity for untrained subjects, and hence, it is not an ideal screening method for glaucoma. By comparison, the screening test of FDT is rapid and easy, but it is probably less suitable for screening purpose, because some eyes with advanced glaucoma were missed in this investigation. GDx VCC images for a relatively large number of eyes could not be analysed and is thus not appropriate for screening. The OCT instruments offer both high sensitivity and high specificity, and all eyes with advanced disease were correctly classified as glaucomatous in this evaluation. However, these instruments are still expensive and require special operator skills. Additional development to obtain OCT instrument that is more compact, easier to use and less expensive might render such tomography suitable as a screening tool for glaucoma.

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.

Towards integrated care: Australia's new model of care for patients with glaucoma

Using shared care to tackle the complexity of optimal patient management.