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.     

A comparison of digital retinal images and 35 mm colour transparencies in detecting and grading diabetic retinopathy

We compared digital retinal images and 35 mm colour transparencies taken with the Canon CR5 retinal camera for the detection and grading of diabetic retinopathy in a clinical setting, in a randomized, blinded study of diabetic patients with a spectrum of severity of diabetic retinopathy. Forty patients were photographed, giving a total of 75 eyes including non-diabetic eyes as controls. Images were graded according to the validated European guidelines. There was exact agreement between grades obtained from both the 2 field 45° 35 mm colour transparencies and digital images in 93.3 % (70/75) of eyes, with Cohen’s Kappa statistic for the comparison being 0.92. Overall, when grading from the digital images 5.3 % (4/75) eyes were undergraded with three cases of sight threatening diabetic retinopathy (STDR) graded as non-sight threatening (NSTDR) (3/48, 6.3 %). One eye was overgraded (1/75, 1.3 %). Two of the three cases of STDR undergraded as NSTDR had small numbers of intra-retinal microvascular abnormalities (IRMA) discernible on the colour transparencies but which were not visible from the digital image. The third had multiple small cotton wool spots graded as laser photocoagulation scars from the digital images. In conclusion there is good to excellent agreement between retinopathy grades using the Canon CR5 digital retinal imaging system compared to 35 mm colour transparencies. © 1998 John Wiley & Sons, Ltd.     

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.     

Methodology for retinal photography and assessment of diabetic retinopathy: the EURODIAB IDDM Complications Study

Summary We present the methodology for 45 retinal photography and detail the development, application and validation of a new system of 45 field grading standards for the assessment of diabetic retinopathy. The systems were developed for the EURODIAB IDDM Complications Study, part of a European Community funded Concerted Action Programme into the epidemiology and prevention of diabetes (EURODIAB). Assessment of diabetic retinopathy was carried out centrally by a trained reader of colour retinal photographs using the newly-developed system. The system proved to be acceptably accurate, repeatable and relatively simple to apply. It compared well with the recognised gold standard 7-field 30 stereo photography (assessed using a modified Airlie House classification scheme), against which the new system was validated in a series of 48 eyes. Selection was as a stratified random sample based on clinical retinopathy status: 5, no retinopathy; 25, non-proliferative retinopathy; 16, proliferative or photocoagulated; plus 2, eyes with potentially confounding lesions (vein occlusion). Simple presence of retinal lesions was correctly detected by both systems in 43 of the 48 eyes, giving 100% agreement on detection. Both systems correctly identified the two known cases of confounding vein occlusion. In eyes with diabetic retinopathy (n=41), when severity was expressed in three groups: mild background, moderate/severe background and proliferative/ photocoagulated, at least one grader (out of five) using the new system matched the verified results in 38 out of 41 (93%) eyes and three or more graders matched in 31 (76%) eyes. Individually the five graders' 2-field allocations agreed well with the verified levels (median number of agreements 37, range 28–43). Repeatability was assessed by measures of within and between observer variation using randomly selected samples of 10% (n=252 eyes) and 5% (n=123 eyes) of the main study, respectively, expressed as a resultant kappa value for chance-corrected proportional agreement. Within observer assessment yielded a kappa of 0.85 and between observers a value of 0.83; indicating very good agreement for both measures. The method is particularly useful for large epidemiological studies, in which participating centres have a limited experience in retinal photography.Abbreviations HMA Haemorrhages and microaneurysms - ETDRS Early Treatment Diabetic Retinopathy Study     

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.     

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.     

Screening for diabetic retinopathy is well received by patients and may improve self-management intentions.

AIMS: To investigate patients' views of screening for diabetic retinopathy and the effects of the screening process on health beliefs and behavioural intentions. SETTING: A retinal screening clinic at a GP surgery in SW England. METHODS: Questionnaires administered before and immediately after screening by retinal photography. RESULTS: One hundred patients attended (94% of those invited); 12 had Type 1 and 88 Type 2 diabetes. Over 90% found the information, and seeing their retinal photograph, helpful. Sixty-three were found to have no problem and 37 had some type of eye problem detected. Overall, patients rated the news given at screening as better than expected (P < 0.001) and even those found to have problems mostly rated the news as good (P < 0.001). Detection of problems led patients to rate their recent eye health more negatively, but to be less pessimistic about future deterioration (P < 0.01). Patients with diabetes-related eye problems were more likely (P < 0.05) to say that they both should and would make changes to their self-management, but only after controlling for duration of diabetes. Those who had had diabetes longest declared least intention to change. CONCLUSIONS: Screening by retinal photography is acceptable to patients. Results suggest that screening modified health beliefs but had limited effect on behavioural intentions, with patients of longer disease duration being more reluctant to change their self-management. Opportunities during retinal screening for advice on self-management could be more effectively exploited.     

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.     

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.     

A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy.

AIMS: To compare the respective performances of digital retinal imaging, fundus photography and slit-lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme. METHODS: A group of 586 patients recruited from a diabetic clinic underwent three or four mydriatic screening methods for retinal examination. The respective performances of digital imaging (n=586; graded manually), colour slides (n=586; graded manually), and slit-lamp examination by specially trained optometrists (n=485), were evaluated against a reference standard of slit-lamp biomicroscopy by ophthalmologists with a special interest in medical retina. The performance of automated grading of the digital images by computer was also assessed. RESULTS: Slit-lamp examination by optometrists for referable diabetic retinopathy achieved a sensitivity of 73% (52-88) and a specificity of 90% (87-93). Using two-field imaging, manual grading of red-free digital images achieved a sensitivity of 93% (82-98) and a specificity of 87% (84-90), and for colour slides, a sensitivity of 96% (87-100) and a specificity of 89% (86-91). Almost identical results were achieved for both methods with single macular field imaging. Digital imaging had a lower technical failure rate (4.4% of patients) than colour slide photography (11.9%). Applying an automated grading protocol to the digital images detected any retinopathy, with a sensitivity of 83% (77-89) and a specificity of 71% (66-75) and diabetic macular oedema with a sensitivity of 76% (53-92) and a specificity of 85% (82-88). CONCLUSIONS: Both manual grading methods produced similar results whether using a one- or two-field protocol. Technical failures rates, and hence need for recall, were lower with digital imaging. One-field grading of fundus photographs appeared to be as effective as two-field. The optometrists achieved the lowest sensitivities but reported no technical failures. Automated grading of retinal images can improve efficiency of resource utilization in diabetic retinopathy screening.     

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.     

糖尿病视网膜病变与勃起功能障碍的关系

目的探讨糖尿病视网膜病变（DR）与勃起功能障碍（ED）的关系。方法对2型糖尿病（T2DM）合并视网膜病变组（DR组）22例、T2DM无视网膜病变组（非DR组）92例用国际勃起功能指数（IIEF）评分,比较两组间的评分情况。结果DR组的评分明显低于非DR组（P〈0．05）,DR组的ED发生率明显高于非DR组（P〈0．05）。结论糖尿病视网膜病变与ED的发生密切相关。     

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.     

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.     

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.