Evaluation of a new non-mydriatic digital camera for detection of diabetic retinopathy.

AIMS: To compare the results of fundus photography using a new non-mydriatic digital camera with the results of reference standard of Early Treatment Diabetic Retinopathy Study (ETDRS) retinal photographs, for the detection of diabetic retinopathy (DR). METHODS: Fundus colour photographs were taken with a Topcon non-mydriatic camera of 147 eyes of 74 diabetic patients, without pupillary dilation (five overlapping fields of 45 degrees; posterior pole, nasal, temporal, superior and inferior). Three retinal specialists classified the photographs in a masked fashion, as showing no DR or mild non-proliferative DR (NPDR) not requiring referral, moderate or more severe NPDR and/or macular oedema, or as non-gradable image requiring referral. ETDRS 35-mm colour slides served as reference images for DR detection. RESULTS: For moderately severe to severe DR, the sensitivities of detection reported by the three observers were 92, 100 and 92%, respectively, and the specificities, 87, 85, and 88%. For four levels of DR severity (none or mild NPDR, moderate NPDR, severe NPDR and proliferative DR), the percentages of exact agreement between the three observers on the retinopathy grades assigned to the non-mydriatic photographs and to the ETDRS reference slides were 94.6, 93 and 87.6%, respectively (kappa 0.60-0.80). Sixteen eyes of nine patients (11%) were judged ungradable by at least one observer. In a second series of 110 patients, evaluated in the setting of a screening procedure, fewer photographs were ungradable (< 6%). CONCLUSION: These results suggest that fundus photographs taken by the Topcon TRC-NW6S non-mydriatic camera, without pupillary dilation, are suitable for DR screening.     

Automated detection of diabetic retinopathy in digital retinal images: a tool for diabetic retinopathy screening.

AIMS: To develop a system to detect automatically features of diabetic retinopathy in colour digital retinal images and to evaluate its potential in diabetic retinopathy screening. METHODS: Macular centred 45 degrees colour retinal images from 1273 patients in an inner city diabetic retinopathy screening programme. A system was used involving pre-processing to standardize colour and enhance contrast, segmentation to reveal possible lesions and classification of lesions using an artificial neural network. The system was trained using a subset of images from 500 patients and evaluated by comparing its performance with a human grader on a test set of images from 773 patients. RESULTS: Maximum sensitivity for detection of any retinopathy on a per patient basis was 95.1%, accompanied by specificity of 46.3%. Specificity could be increased as far as 78.9% but was accompanied by a fall in sensitivity to 70.8%. At a setting with 94.8% sensitivity and 52.8% specificity, no cases of sight-threatening retinopathy were missed (retinopathy warranting immediate ophthalmology referral or re-examination sooner than 1 year by National Institute for Clinical Excellence criteria). If the system was implemented at 94.8% sensitivity setting over half the images with no retinopathy would be correctly identified, reducing the need for a human grader to examine images in 1/3 of patients. CONCLUSION: This system could be used when screening for diabetic retinopathy. At 94.8% sensitivity setting the number of normal images requiring examination by a human grader could be halved.     

The effectiveness of screening for diabetic retinopathy by digital imaging photography and technician ophthalmoscopy.

AIMS: To evaluate the introduction of a community-based non-mydriatic and mydriatic digital photographic screening programme by measuring the sensitivity and specificity compared with a reference standard and assessing the added value of technician direct ophthalmoscopy. METHODS: Study patients had one-field, non-mydriatic, 45 degrees digital imaging photography prior to mydriatic two-field digital imaging photography followed by technician ophthalmoscopy. Of these patients, 1549 were then examined by an experienced ophthalmologist using slit lamp biomicroscopy as a reference standard. The setting was general practices in Gloucestershire. Patients were selected by randomizing groups of patients (from within individual general practices) and 3611 patients were included in the study. Patients for reference standard examination were recruited from groups of patients on days when the ophthalmologist was able to attend. The main outcome measure was detection of referable diabetic retinopathy (DR) as defined by the Gloucestershire adaptation of the European Working Party guidelines. RESULTS: For mydriatic digital photography, the sensitivity was 87.8%, specificity was 86.1% and technical failure rate was 3.7%. Technician ophthalmoscopy did not alter these figures. For non-mydriatic photography, the sensitivity was 86.0%, specificity was 76.7% and technical failure rate was 19.7%. CONCLUSIONS: Two-field mydriatic digital photography is an effective method of screening for referable diabetic retinopathy. Non-mydriatic digital photography has an unacceptable technical failure rate and low specificity.     

Current status of screening for diabetic retinopathy in the UK

This article reviews the current status of retinopathy screening schemes in the UK. There is evidence that high‐quality diabetic retinopathy screening schemes are in existence but provision is patchy. Many health authorities have ad hoc screening programmes reaching only about 60% of patients, with unacceptable or undocumented efficacy and minimal quality control. Several models of screening are currently in use with the current preferred option being camera‐based screening. Digital imaging systems offer the best prospects for image acquisition, although at present evidence of adequate effectiveness only exists for 35 mm film‐based systems. The final report of the National Diabetic Retinopathy Screening Programme commissioned by the UK National Screening Committee for inclusion into the national service framework for diabetes, is thus eagerly awaited and should set standards for screening programmes, in order to improve the care of all those with diabetes. Quality assurance will be the main driver in the immediate future of improvements in screening programmes. Research data will provide the evidence to refine techniques and set targets in the longer term, with the emphasis on cost‐effectiveness and quality of life.     

Screening for diabetic retinopathy in South Africa with 60° retinal colour photography

Objectives. Comparison of 60° mydriatic retinal photography, in screening for diabetic retinopathy, with diabetes clinic doctors, formal ophthalmological assessment, and with one or two 45° fields.
Design. Consecutive subjects screened by clinicians and photography, and selected eyes evaluated by an ophthalmologist. Randomized photographs assessed through one or two 45° fields (by masking the slides), and at 60°.
Setting. The first 663 patients attending for routine clinic visits and screened for retinopathy.
Main outcome measures. The relative diagnostic sensitivity of screening methods, the utility of screening one eye only, and the costs of photographic screening.
Results. Compared to an ophthalmologist's assessment, retinal photography had a sensitivity of 93% and a specificity of 89% for any retinopathy, and 100 and 75%, respectively, for severe retinopathy. Photography detected 28% more retinopathy (16% severe) than the clinicians. Compared to a 60° field, one 45° field missed 31%, and 2×45° fields 11% of retinopathy. Of 57 patients with retinopathy meeting referral criteria, 31 pairs of eyes had substantially discordant scores. The cost of diagnosis in a patient requiring referral to ophthalmologist was about US$37.00.
Conclusions. 60° retinal photography compares well with an ophthalmologists screening, and is better than clinical and one to two 45° field assessments. Both retinae should be screened. This method is cost-effective in our hands.     

Quality assurance in screening for sight-threatening diabetic retinopathy.

AIMS: There is a need for continuous evaluation of screening services for diabetic retinopathy against agreed performance standards. We describe a quality assurance programme implemented in Newcastle in January 1999 and report on outcomes at 18 months. METHODS: Annual retinal screening is performed using combined retinal photography and direct ophthalmoscopy in two streams. Diabetologists perform screening in the Hospital Screening Programme, which serves patients whose diabetes is managed in specialist clinics, and trained retinal screeners perform screening in the District Screening Programme, which serves patients whose diabetes is managed in the community. Reference standard examination of dilated fundoscopy with a slit-lamp and condensing lens was performed by an ophthalmologist at periodic sessions on consecutive patients attending for screening. RESULTS: Six hundred and nine (6.4%) of 9468 patients screened underwent reference standard examination. The sensitivity and specificity of detection of sight-threatening diabetic retinopathy (STDR) was 82.5% and 98%, respectively, for the Hospital Screening Programme; 85.7% and 95.7%, respectively, for the District Screening Programme; and 83.3% and 96.8% for both services combined. One hundred and ten (18.1%) of 609 patients audited were referred to ophthalmology as a result of screening, and this led to 16 patients (2.6%) receiving laser photocoagulation for STDR. Reference standard examination identified a further four patients (0.7%) who required laser photocoagulation. CONCLUSIONS: Preliminary data indicate that satisfactory performance standards are being achieved. The National Service Framework for Diabetes requires that all units institute quality assurance for retinal screening, and we report the practical implementation of this in one district.     

Assessing progression and efficacy of treatment for diabetic retinopathy following the proliferative pathway to blindness: implication for diabetic retinopathy screening in Taiwan.

AIMS: The natural history and treatment efficacy of diabetic retinopathy (DR) play important roles in the evaluation of screening. Therefore, the natural history of DR and rates of transition after treatment (including metabolic control and laser photocoagulation) from no diabetic retinopathy (NDR) to blindness were quantified. METHODS: We studied a cohort of 795 patients with diabetes mellitus (DM) receiving fundus examination in the ophthalmology out-patient department of one medical centre between 1 January 1990 and 31 December 1992 in Taiwan. Follow-up data until 31 December 1998 were collected by chart review. Two multistate Markov models were proposed to assess the efficacy of the treatment regime in reducing progression to blindness. RESULTS: The average times spent in states (i) no diabetic retinopathy (NDR), (ii) background diabetic retinopathy (BDR), (iii) preproliferative diabetic retinopathy (PPDR), and (iv) proliferative retinopathy (PDR) were 10.86 years, 8.33 years, 1.67 years, and 2.17 years, respectively. Early detection of PPDR may lead to a 60% reduction in PDR and an 83% reduction in blindness. Simulated results based on these parameters show that an annual screening programme, a biennial screening regime and a 4-yearly screening regime can lead to 54% (95% confidence interval (CI): 44-62%), 51% (95% CI: 41-59%), and 46% (95% CI: 36-54%) reductions in blindness, respectively. CONCLUSIONS: Assessing the progression of DR following the proliferative pathway in this study suggests that screening for DR is worthwhile and that a 4-year interscreening interval for patients as yet without DR may be justified.     

Sensitivity and specificity of digital retinal imaging for screening diabetic retinopathy.

AIMS: To assess the effectiveness of a non-mydriatic digital camera (45 degrees -30 degrees photographs) compared with the reference method for screening diabetic retinopathy. METHODS: Type 1 and 2 diabetic patients (n = 773; 1546 eyes) underwent screening for diabetic retinopathy in a prospective observational study. Hospital-based non-mydriatic digital retinal imaging by a consultant specialist in retinal diseases was compared with slit-lamp biomicroscopy and indirect ophthalmoscopy through dilated pupils, as a gold standard, previously performed in a community health centre by another consultant specialist in retinal diseases. The main outcome measures were sensitivity and specificity of screening methods and prevalence of diabetic retinopathy. RESULTS: The prevalence of any form of diabetic retinopathy was 42.4% (n = 328); the prevalence of sight-threatening including macular oedema and proliferative retinopathy was 9.6% (n = 74). Sensitivity of detection of any diabetic retinopathy by digital imaging was 92% (95% confidence interval 90, 94). Specificity of detection of any diabetic retinopathy was 96% (95, 98). The predictive value of the negative tests was 94% and of a positive test 95%. For sight-threatening retinopathy digital imaging had a sensitivity of 100%. CONCLUSIONS: A high sensitivity and specificity are essential for an effective screening programme. These results confirm digital retinal imaging with a non-mydriatic camera as an effective option in community-based screening programmes for diabetic retinopathy.     

Survey of diabetic retinopathy screening services in England and Wales

A postal survey of diabetologists was conducted regarding the provision of diabetic retinopathy screening services in England and Wales. About 2.5 million people had no existing or planned screening service. For the rest, the perceived percentage of patients with diabetes screened varied from less than 25 % to more than 90 %. Multiple modes of screening were used in most units. Lack of funding was identified as the major reason for non-provision of an adequate screening service. About 18 % of the units had to use research or charitable funds for screening. Only 50 % of the units using optometrists for screening had standard protocols for referral. The average wait before an ophthalmologist’s opinion on sight threatening retinopathy detected by screening was unacceptably high in some units. We would suggest that establishment of identical screening protocols and provision of adequate funding on a national basis ought to be the priority if incidence of blindness from diabetic retinopathy is to be reduced according to the St Vincent Declaration. © 1998 John Wiley & Sons, Ltd.     

免散瞳眼底拍照对糖尿病视网膜病变筛查效果的评价

目的 评价免散瞳眼底拍照诊断糖尿病视网膜病变(DR)的效果.方法 104例高血糖患者均行免散瞳眼底拍照(NMFCS)和散瞳后7个标准视野眼底彩照(SSSCFP)检查.结果 发现任何程度的DR,NMFCS与SSSCFP间有高度一致性(к=0.75±0.03);发现需推荐眼科诊治的DR患者,二者间也有极好的一致性(к=0.85±0.05).结论 NMFCS适用于高血糖人群的DR筛查,对DR的分诊和治疗有指导意义.     

Evaluation of a combination digital retinal camera with spectral-domain optical coherence tomography (SD-OCT) that might be used for the screening of diabetic retinopathy with telemedicine: A pilot study

Aims

Pilot study to determine whether an instrument combining a non-mydriatic retinal camera and spectral domain optical coherence tomography (SD-OCT) is effective for screening patients with diabetic retinopathy (DR).

The evaluation of screening policies for diabetic retinopathy using simulation.

AIMS: To develop a model for evaluating screening strategies and to use it to determine the cost effectiveness of varying the screening method and the screening interval. METHODS: A discrete event simulation was designed, validated and run for a population of 500000. Most parameters were derived from peer-reviewed publications. RESULTS: Standard methods of screening save up to 50% of the potential sight years lost. They give up to 85% of the sight years saved by an idealized gold standard programme using mydriatic seven-field photography reported by an ophthalmologist. The mobile camera, used for annual screening and 6-month follow-up after the detection of background retinopathy, had an estimated cost of pound 449200 per year with pound 2842 per sight year saved. It is less efficient to screen Type 2, rather than Type 1 diabetes mellitus patients, but they contributed to almost three-quarters of the sight years saved. CONCLUSIONS: The model can evaluate screening intervals and methods on a national or health authority basis. Results indicate that it appears more cost effective to continue to screen outside an ophthalmology clinic, until treatment is needed. Programmes with annual screening, and more frequent screening for those with background retinopathy, are robust to realistic fluctuations in compliance and screening sensitivity.     

Prevalence of diabetic eye disease in patients entering a systematic primary care-based eye screening programme.

AIMS: Large-scale, baseline prevalence measurements in a population at the institution of systematic retinal screening are currently unavailable. We report the prevalence of all grades of retinopathy at entry into a systematic primary care-based diabetic eye screening programme. METHODS: Primary care-based photographic screening utilizing mydriasis and three-field non-stereoscopic photography for all patients with diabetes (except those under continuing care of an ophthalmologist) in Liverpool. Sight-threatening diabetic eye disease (STED) was defined as any of: moderate preproliferative retinopathy or worse, circinate maculopathy or exudates within one disc diameter of the centre of fovea. RESULTS: Type 1 diabetes mellitus (DM) (n = 831): baseline prevalence (95% confidence interval (CI)) of any retinopathy, proliferative diabetic retinopathy (PDR) and STED was 45.7% (42.3-49.1), 3.7% (2.4-5.0) and 16.4% (13.9-18.9), respectively. Presence of STED was associated with increased disease duration (odds ratio (OR) 1.09 per year; P < 0.0001) and higher in men (OR 2.15; P = 0.001). Type 2 DM (n = 7231): baseline prevalence (95% CI) of any retinopathy, PDR and STED was 25.3% (24.3-26.3), 0.5% (0.3-0.7) and 6.0% (5.5-6.5), respectively. Presence of STED was associated with longer time since diagnosis of DM (OR 1.03; P < 0.0001) and insulin use (OR 2.46; P < 0.0001). CONCLUSION: This study provides baseline information for health providers on prevalence of all grades of retinopathy and STED in a large population at the establishment of systematic screening. Baseline prevalence of STED was high and highest in patients with a longer disease duration in both Type 1 and Type 2 DM.     

Quality assurance for diabetic retinopathy telescreening.

AIMS: TOSCA was an EU-Commission supported international research project designed to develop telescreening services in diabetic retinopathy and glaucoma. This paper describes the quality assurance methods developed for the diabetic retinopathy telescreening service within the TOSCA project. SETTING: The study was performed in 1895 patients with diabetes between 2000 and 2002 at diabetic retinopathy screening sites in five European countries. Data were analysed centrally. METHODS: Patients attending each clinic's diabetic retinopathy screening service received standardized retinal photography. The images and associated data were transferred electronically to a remote location for grading. Each photographer uploading images and each grader downloading images for assessment was controlled by a systematic quality management approach. The quality assurance measures defined were image quality, intragrader reliability. A cockpit chart was developed for the management and presentation of relevant results and quality measures. For the intragrader reliability tests, 10% of the images were processed for a second grading. An algorithm for calculating differences between repeated gradings was developed. RESULTS: The assessment of image quality for the different sites showed that only 0-0.7% were unassessable. One hundred per cent agreement for both gradings was achieved in 50-85% of graded cases, depending on site and grader, and an agreement better than 95% in 71-100% of cases. CONCLUSIONS: A telemedicine-supported quality assurance process is practical and advantageous. The cockpit charts have proven to be useful tools when monitoring the performance of a telescreening service. Grader feedback showed high satisfaction with the quality assurance process.     

An assessment of the coverage of a district-wide diabetic retinopathy screening service.

AIMS: To assess the coverage of the diabetes retinopathy screening service (DRSS) in North Staffordshire, to identify patient characteristies associated with non-attendance and to assess the proportion of patients with diabetic retinopathy who achieved glycaemic and blood pressure (BP) control targets. METHODS: Data for all patients who underwent annual retinal screening between 1 May 2000 and 30 April 2001 were obtained from the North Staffordshire Diabetes Register. Age, gender, ethnicity, socio-economic status, type and duration of diabetes were compared between patients who underwent eye screening and those who did not. Frequencies of patients who achieved glycaemic and BP targets in these groups of patients were compared to the remaining patients. RESULTS: 5646 of the 11682 (48%) patients on the diabetes register underwent retinal screening during the year. Patients with Type 2 diabetes, older patients, patients belonging to ethnic minorities and those wholly managed in primary care were less likely to attend for eye screening (P < 0.05 for all groups) with ethnic minority or primary care management demonstrating independent influence (P < 0.001). The percentage of patients with retinopathy achieving HbA1c and systolic BP targets was significantly lower than in their unaffected counterparts (chi2 = 63, P < 0.001 and chi2 = 71, P < 0.001 respectively). CONCLUSIONS: The efficacy of the DRSS in North Staffordshire is low and might be improved by targeting specific patient groups. Glycaemic control and systolic BP control needs to be improved in patients with diabetic retinopathy.     

Screening for diabetic retinopathy in a widely spaced population using non-mydriatic fundus photography in a mobile unit. Tayside Mobile Eye Screening Unit.

A screening project was established to assess the prevalence and severity of retinopathy in diabetic patients in Tayside (area: 3000 square miles, population: 390,000). A questionnaire was used to examine patient acceptability. Of 2112 patients photographed during the first year, 32% had abnormal photographs; 20.2% had diabetic retinopathy; 7.4% cataracts; 4.6% non-diabetic eye disease. Among this patient population, 73% were registered at a hospital diabetic clinic. The overall prevalence of diabetic retinopathy was similar between the two groups (hospital 23% vs non-hospital 20%). The prevalence of severe diabetic retinopathy was also similar (hospital 8.5% vs non-hospital 10%). This had been previously unrecognized or incorrectly defined in 6.5% of those not attending a hospital diabetic clinic, compared to 3.7% attending the hospital clinic (p less than 0.01). A favourable response to the service was indicated by 40% of patients with 7% unfavourable and 41% uncommitted. Non-mydriatic fundal photography housed in a mobile unit is a practical and effective method of assessing diabetic retinopathy. It is particularly suitable for screening in a widely spread population.     

Integrating diabetic retinopathy screening within diabetes education services in Australia's diabetes and indigenous primary care clinics

As diabetes occurs in all ethnicities and regions it is essential that retinopathy screening be widely available. Screening rates are lower in Indigenous than in non‐Indigenous Australians. Technological advances and Medicare rebates should facilitate improved outcomes. Use of non‐ophthalmic clinicians, (general practitioners, diabetes educators, health‐workers and endocrinologists) to supplement coverage by ophthalmologists and optometrists would extend retinopathy screening capacity. Diabetes educators are an integral part of diabetes management. Integrating ocular screening and diabetes education in primary care settings has potential to improve synergistically retinopathy screening coverage, patient self‐management, risk factor control, care satisfaction, health economics and sustainability of under‐resourced services.     

DrishtiCare: a telescreening platform for diabetic retinopathy powered with fundus image analysis

Objective:

Diabetic retinopathy is the leading cause of blindness in urban populations. Early diagnosis through regular screening and timely treatment has been shown to prevent visual loss and blindness. It is very difficult to cater to this vast set of diabetes patients, primarily because of high costs in reaching out to patients and a scarcity of skilled personnel. Telescreening offers a cost-effective solution to reach out to patients but is still inadequate due to an insufficient number of experts who serve the diabetes population. Developments toward fundus image analysis have shown promise in addressing the scarcity of skilled personnel for large-scale screening. This article aims at addressing the underlying issues in traditional telescreening to develop a solution that leverages the developments carried out in fundus image analysis.

Method

We propose a novel Web-based telescreening solution (called DrishtiCare) integrating various value-added fundus image analysis components. A Web-based platform on the software as a service (SaaS) delivery model is chosen to make the service cost-effective, easy to use, and scalable. A server-based prescreening system is employed to scrutinize the fundus images of patients and to refer them to the experts. An automatic quality assessment module ensures transfer of fundus images that meet grading standards. An easy-to-use interface, enabled with new visualization features, is designed for case examination by experts.

Results

Three local primary eye hospitals have participated and used DrishtiCare’s telescreening service. A preliminary evaluation of the proposed platform is performed on a set of 119 patients, of which 23% are identified with the sight-threatening retinopathy. Currently, evaluation at a larger scale is under process, and a total of 450 patients have been enrolled.

Conclusion:

The proposed approach provides an innovative way of integrating automated fundus image analysis in the telescreening framework to address well-known challenges in large-scale disease screening. It offers a low-cost, effective, and easily adoptable screening solution to primary care providers.