Comparison of two reference standards in validating two field mydriatic digital photography as a method of screening for diabetic retinopathy

Effect of Visual Impairment on Teleretinal Imaging for Diabetic Retinopathy Screening

BACKGROUND AND OBJECTIVE

To evaluate the effect of decreased visual acuity on image quality obtained by non-mydriatic retinal photography in diabetic subjects. PATIENTS AND METHODS This case-control study comprised 422 eyes (211 cases with ungradable images after non-mydriatic retinal photography, and 211 controls). All subjects underwent complete ophthalmic examination. The association between ungradable image rate and several eye factors, such as corrected distance visual acuity (CDVA), spherical equivalent (SE), astigmatism, and cataracts, was evaluated using a generalized estimating equations model.

RESULTS

Visual impairment (Snellen CDVA worse than 20/40) was significantly associated with an increased likelihood of ungradable images. The odds ratio (OR) for this association was 7.79 (95% CI, 4.19-14.50; P < .0001). This relationship remained significant in the multivariable model (OR: 5.23; 95% CI, 2.82-9.71; P < .0001). Similarly, refractive error worse than -6.0 diopters (D) SE or +5.0 D SE was associated with increased risk of ungradable scans, with an OR of 13.21 (95% CI, 2.61-66.77; P = .002).

CONCLUSION

Decreased visual acuity may be a predictor of inaccurate image analysis in subjects screened for diabetic retinopathy by non-mydriatic retinal photography.

The use of statistical methodology to determine the accuracy of grading within a diabetic retinopathy screening programme

AIMS

We aimed to use longitudinal data from an established screening programme with good quality assurance and quality control procedures and a stable well-trained workforce to determine the accuracy of grading in diabetic retinopathy screening.

METHODS

We used a continuous time-hidden Markov model with five states to estimate the probability of true progression or regression of retinopathy and the conditional probability of an observed grade given the true grade (misclassification). The true stage of retinopathy was modelled as a function of the duration of diabetes and HbA1c .

RESULTS

The modelling dataset consisted of 65 839 grades from 14 187 people. The median number [interquartile range (IQR)] of examinations was 5 (3, 6) and the median (IQR) interval between examinations was 1.04 (0.99, 1.17) years. In total, 14 227 grades (21.6%) were estimated as being misclassified, 10 592 (16.1%) represented over-grading and 3635 (5.5%) represented under-grading. There were 1935 (2.9%) misclassified referrals, 1305 were false-positive results (2.2%) and 630 were false-negative results (1.0%). Misclassification of background diabetic retinopathy as no detectable retinopathy was common (3.4% of all grades) but rarely preceded referable maculopathy or retinopathy.

CONCLUSION

Misclassification between lower grades of retinopathy is not uncommon but is unlikely to lead to significant delays in referring people for sight-threatening retinopathy.

Development of a cost-effectiveness model for optimisation of the screening interval in diabetic retinopathy screening

BACKGROUND

The English NHS Diabetic Eye Screening Programme was established in 2003. Eligible people are invited annually for digital retinal photography screening. Those found to have potentially sight-threatening diabetic retinopathy (STDR) are referred to surveillance clinics or to Hospital Eye Services.

OBJECTIVES

To determine whether personalised screening intervals are cost-effective.

DESIGN

Risk factors were identified in Gloucestershire, UK using survival modelling. A probabilistic decision hidden (unobserved) Markov model with a misgrading matrix was developed. This informed estimation of lifetime costs and quality-adjusted life-years (QALYs) in patients without STDR. Two personalised risk stratification models were employed: two screening episodes (SEs) (low, medium or high risk) or one SE with clinical information (low, medium-low, medium-high or high risk). The risk factor models were validated in other populations.

SETTING

Gloucestershire, Nottinghamshire, South London and East Anglia (all UK).

PARTICIPANTS

People with diabetes in Gloucestershire with risk stratification model validation using data from Nottinghamshire, South London and East Anglia.

MAIN OUTCOME MEASURES

Personalised risk-based algorithm for screening interval; cost-effectiveness of different screening intervals.

RESULTS

Data were obtained in Gloucestershire from 12,790 people with diabetes with known risk factors to derive the risk estimation models, from 15,877 people to inform the uptake of screening and from 17,043 people to inform the health-care resource-usage costs. Two stratification models were developed: one using only results from previous screening events and one using previous screening and some commonly available GP data. Both models were capable of differentiating groups at low and high risk of development of STDR. The rate of progression to STDR was 5 per 1000 person-years (PYs) in the lowest decile of risk and 75 per 1000 PYs in the highest decile. In the absence of personalised risk stratification, the most cost-effective screening interval was to screen all patients every 3 years, with a 46% probability of this being cost-effective at a £30,000 per QALY threshold. Using either risk stratification models, screening patients at low risk every 5 years was the most cost-effective option, with a probability of 99-100% at a £30,000 per QALY threshold. For the medium-risk groups screening every 3 years had a probability of 43-48% while screening high-risk groups every 2 years was cost-effective with a probability of 55-59%.

CONCLUSIONS

The study found that annual screening of all patients for STDR was not cost-effective. Screening this entire cohort every 3 years was most likely to be cost-effective. When personalised intervals are applied, screening those in our low-risk groups every 5 years was found to be cost-effective. Screening high-risk groups every 2 years further improved the cost-effectiveness of the programme. There was considerable uncertainty in the estimated incremental costs and in the incremental QALYs, particularly with regard to implications of an increasing proportion of maculopathy cases receiving intravitreal injection rather than laser treatment. Future work should focus on improving the understanding of risk, validating in further populations and investigating quality issues in imaging and assessment including the potential for automated image grading.

STUDY REGISTRATION

Integrated Research Application System project number 118959.

FUNDING DETAILS

The National Institute for Health Research Health Technology Assessment programme.

Validation of Smartphone Based Retinal Photography for Diabetic Retinopathy Screening

Aim

To evaluate the sensitivity and specificity of “fundus on phone’ (FOP) camera, a smartphone based retinal imaging system, as a screening tool for diabetic retinopathy (DR) detection and DR severity in comparison with 7-standard field digital retinal photography.

Design

Single-site, prospective, comparative, instrument validation study.

Methods

301 patients (602 eyes) with type 2 diabetes underwent standard seven-field digital fundus photography with both Carl Zeiss fundus camera and indigenous FOP at a tertiary care diabetes centre in South India. Grading of DR was performed by two independent retina specialists using modified Early Treatment of Diabetic Retinopathy Study grading system. Sight threatening DR (STDR) was defined by the presence of proliferative DR(PDR) or diabetic macular edema. The sensitivity, specificity and image quality were assessed.

Results

The mean age of the participants was 53.5 ±9.6 years and mean duration of diabetes 12.5±7.3 years. The Zeiss camera showed that 43.9% had non-proliferative DR(NPDR) and 15.3% had PDR while the FOP camera showed that 40.2% had NPDR and 15.3% had PDR. The sensitivity and specificity for detecting any DR by FOP was 92.7% (95%CI 87.8–96.1) and 98.4% (95%CI 94.3–99.8) respectively and the kappa (ĸ) agreement was 0.90 (95%CI-0.85–0.95 p<0.001) while for STDR, the sensitivity was 87.9% (95%CI 83.2–92.9), specificity 94.9% (95%CI 89.7–98.2) and ĸ agreement was 0.80 (95%CI 0.71–0.89 p<0.001), compared to conventional photography.

Conclusion

Retinal photography using FOP camera is effective for screening and diagnosis of DR and STDR with high sensitivity and specificity and has substantial agreement with conventional retinal photography.

New vessels detected on wide-field imaging compared to two-field and seven-field imaging: implications for diabetic retinopathy screening image analysis

Introduction

Wide-field retinal imaging (Optomap), used for detecting diabetic retinopathy (DR), has been shown to compare well with seven-field early treatment diabetic retinopathy study (ETDRS) photographs. An Optomap 200° image covers 80% of the retinal surface, compared with the standard seven-field, 30° images, covering 30% of the retinal surface. In England, DR screening is performed by grading two, 45° images per eye, by the DR screening service (DRSS).

Purpose

To assess how often retinal new vessels (NVs) are observed on Optomap imaging, outside the DRSS two fields and standard seven-field photography, in a cohort of patients referred by the DRSS.

Method

A consecutive series of treatment naïve patients with DR, referred from DRSS with pre-proliferative or proliferative DR or diabetic maculopathy, were imaged with Optomap colour images, within 3 months of DRSS referral. The incidence and distribution of NVs were recorded in relation to two-field and seven-field areas.

Results

NVs were found in 102 of 1562 treatment naïve eyes (6.5%) of 781 patients. Of these, 72 were referred from DRSS as having NVs, but an additional 30 eyes (29% of NVs detected) from 25 patients were referred with a lesser degree of DR. In 25 of the 30 eyes without NVs reported on referral, NVs were located outside the standard two fields taken at DRSS, and in 12, NVs were outside the area covered on seven-field imaging (11.7% of eyes with NVs).

Conclusions

Wide-field imaging with Optomap detected approximately 30% more NVs than standard two-field imaging in patients referred from a UK DRSS.

Automated multi-lesion detection for referable diabetic retinopathy in indigenous health care

Diabetic Retinopathy (DR) is a complication of diabetes mellitus that affects more than one-quarter of the population with diabetes, and can lead to blindness if not discovered in time. An automated screening enables the identification of patients who need further medical attention. This study aimed to classify retinal images of Aboriginal and Torres Strait Islander peoples utilizing an automated computer-based multi-lesion eye screening program for diabetic retinopathy. The multi-lesion classifier was trained on 1,014 images from the São Paulo Eye Hospital and tested on retinal images containing no DR-related lesion, single lesions, or multiple types of lesions from the Inala Aboriginal and Torres Strait Islander health care centre. The automated multi-lesion classifier has the potential to enhance the efficiency of clinical practice delivering diabetic retinopathy screening. Our program does not necessitate image samples for training from any specific ethnic group or population being assessed and is independent of image pre- or post-processing to identify retinal lesions. In this Aboriginal and Torres Strait Islander population, the program achieved 100% sensitivity and 88.9% specificity in identifying bright lesions, while detection of red lesions achieved a sensitivity of 67% and specificity of 95%. When both bright and red lesions were present, 100% sensitivity with 88.9% specificity was obtained. All results obtained with this automated screening program meet WHO standards for diabetic retinopathy screening.

Body mass index and retinopathy in Asian populations with diabetes mellitus

Body mass index (BMI) is an established risk factor for diabetes. However, the association between BMI and diabetic retinopathy (DR) has been inconclusive. We aimed to assess the association between BMI and DR in a large population-based sample of multi-ethnic Asian adults in Singapore. We examined 2,278 adults aged ≥40 years with diabetes who participated in three population-based studies conducted from 2004 to 2011: the Singapore Malay Eye Study, the Singapore Indian Eye Study, and the Singapore Chinese Eye Study. Retinal photographs taken from both eyes were graded for any and vision-threatening (VTDR) using the modified Airlie House Classification. BMI (kg/m(2)) was categorized into normal/underweight (<25), overweight (25-29.9), and obese (≥30). The prevalence rates of any and VTDR in the study population were 35.1 % and 9.1 %, respectively. The prevalence of any and VTDR decreased with increasing categories of BMI (P trend <0.001 and 0.005). In multivariable models adjusted for potential confounders, compared to those with normal weight, the odds ratio (95 % confidence interval) of any DR was 0.71 (0.57-0.88) for overweight and 0.70 (0.53-0.92) for obese. Corresponding estimates for VTDR were 0.84 (0.59-1.21) for overweight and 0.58 (0.35-0.94) for obese. The inverse association between BMI and any DR was consistently present when BMI was analyzed as a continuous variable and in analyses stratified by ethnicity and age. In a population-based sample of multi-ethnic Asian adults, BMI levels were inversely associated with any DR and VTDR.

Wide-field imaging and OCT vs clinical evaluation of patients referred from diabetic retinopathy screening

Purpose

Compare wide-field Optomap imaging and optical coherence tomography (OCT) with clinical examination in diabetic retinopathy (DR).

Methods

Patients referred from Diabetic Eye Screening Programmes to three centres underwent dilated ophthalmoscopy and were assigned a DR grade. Wide-field colour imaging and OCT were then examined by the same clinician at that visit and a combined grade was assigned. Independent graders later reviewed the images and assigned an imaging-only grade. These three grades (clinical, combined, and imaging) were compared. The method that detected the highest grade of retinopathy, including neovascularisation, was determined.

Results

Two thousand and forty eyes of 1023 patients were assessed. Wide-field imaging compared with clinical examination had a sensitivity and specificity of 73% and 96%, respectively, for detecting proliferative DR, 84% and 69% for sight-threatening DR, and 64% and 90% for diabetic macular oedema. Imaging alone found 35 more eyes with new vessels (19% of eyes with new vessels) and the combined grade found 14 more eyes than clinical examination alone.

Conclusions

Assessment of wide-field images and OCT alone detected more eyes with higher grades of DR compared with clinical examination alone or when combined with imaging in a clinical setting. The sensitivity was not higher as the techniques were not the same, with imaging alone being more sensitive. Wide-field imaging with OCT could be used to assess referrals from DR screening to determine management, to enhance the quality of assessment in clinics, and to follow-up patients whose DR is above the screening referral threshold but does not actually require treatment.

Extending the diabetic retinopathy screening interval beyond 1 year: systematic review

To determine whether the recommended screening interval for diabetic retinopathy (DR) in the UK can safely be extended beyond 1 year. Systematic review of clinical and cost-effectiveness studies. Nine databases were searched with no date restrictions. Randomised controlled trials (RCTs), cohort studies, prognostic or economic modelling studies which described the incidence and progression of DR in populations with type 1 diabetes mellitus or type 2 diabetes mellitus of either sex and of any age reporting incidence and progression of DR in relation to screening interval (vs annual screening interval) and/or prognostic factors were included. Narrative synthesis was undertaken. 14 013 papers were identified, of which 11 observational studies, 5 risk stratification modelling studies and 9 economic studies were included. Data were available for 262 541 patients of whom at least 228 649 (87%) had type 2 diabetes. There were no RCTs. Studies concluded that there is little difference between clinical outcomes from screening 1 yearly or 2 yearly in low-risk patients. However there was high loss to follow-up (13–31%), heterogeneity in definitions of low risk and variation in screening and grading protocols for prior retinopathy results. Observational and economic modelling studies in low-risk patients show little difference in clinical outcomes between 1-year and 2-year screening intervals. The lack of experimental research designs and heterogeneity in definition of low risk considerably limits the reliability and validity of this conclusion. Cost-effectiveness findings were mixed. There is insufficient evidence to recommend a move to extend the screening interval beyond 1 year.

25th RCOphth Congress, President's Session paper: 25 years of progress in medical retina

The quarter century since the foundation of the Royal College of Ophthalmologists has coincided with immense change in the subspecialty of medical retina, which has moved from being the province of a few dedicated enthusiasts to being an integral, core part of ophthalmology in every eye department. In age-related macular degeneration, there has been a move away from targeted, destructive laser therapy, dependent on fluorescein angiography to intravitreal injection therapy of anti-growth factor agents, largely guided by optical coherence tomography. As a result of these changes, ophthalmologists have witnessed a marked improvement in visual outcomes for their patients with wet age-related macular degeneration (AMD), while at the same time developing and enacting entirely novel ways of delivering care. In the field of diabetic retinopathy, this period also saw advances in laser technology and a move away from highly destructive laser photocoagulation treatment to gentler retinal laser treatments. The introduction of intravitreal therapies, both steroids and anti-growth factor agents, has further advanced the treatment of diabetic macular oedema. This era has also seen in the United Kingdom the introduction of a coordinated national diabetic retinopathy screening programme, which offers an increasing hope that the burden of blindness from diabetic eye disease can be lessened. Exciting future advances in retinal imaging, genetics, and pharmacology will allow us to further improve outcomes for our patients and for ophthalmologists specialising in medical retina, the future looks very exciting but increasingly busy.

Diagnostic accuracy of direct ophthalmoscopy for detection of diabetic retinopathy using fundus photographs as a reference standard

AIMS

To determine the diagnostic accuracy of direct ophthalmoscopy for the presence and severity of diabetic retinopathy (DR) using fundus photographs as a reference standard.

METHODS

Patients with type 2 diabetes attending the outpatient department (OPD) of a tertiary care diabetes center, from October 2009 to March 2010 were recruited in the study after obtaining signed informed consent. Patients with type 1 diabetes and gestational diabetes or having eye problems were excluded. After checking visual acuity, direct ophthalmoscopy of each eye was done by diabetologist, followed by photography of two fields of retina by fundus camera. DR was graded by a retinal specialist, according to International Diabetic Retinopathy Disease Severity Scale. According to severity, patients with DR were grouped into non-sight threatening diabetic retinopathy (NSTDR) and sight threatening diabetic retinopathy (STDR). Sensitivity and specificity of direct ophthalmoscopy for detection of any retinopathy, NSTDR and STDR was calculated.

RESULTS

A total of 728 eyes were examined by direct ophthalmoscopy as well as fundus photography. Sensitivity (95% CI) of direct ophthalmoscopy for any retinopathy, NSTDR and STDR was found to be 55.67% (50.58-60.78), 37.63% (32.67-42.59) and 68.25% (63.48-73.02) respectively. Whereas, specificity of direct ophthalmoscopy was found to be 76.78% (72.45-81.11), 71.27% (CI: 66.63-75.91) and 90.0% (86.93-93.07) for any retinopathy, NSTDR and STDR respectively.

CONCLUSION

The sensitivity and specificity of direct ophthalmoscopy performed by the diabetologist for the presence and severity of DR was lower compared to the recommended level of sensitivity and specificity of a screening test of DR.

Evaluation of diabetic retinopathy screening using a non-mydriatic retinal digital camera in primary care settings in south Israel

To evaluate the effectiveness of the non-mydriatic digital camera for diabetic retinopathy (DR) screening. Secondary purposes of the study were to characterize diabetic patients being screened for the presence of DR and to calculate the sensitivity, specificity, and positive predictive value of the test. All 6,962 consecutive patients with type 2 diabetes undergoing non-mydriatic digital retinal photography between January 1, 2009 and June 30, 2010 in eight community health clinics in the south of the country were included. Comparison of a random sample of patients who underwent non-mydriatic retinal photography, and who were also examined by an ophthalmologist with pupil dilation was also performed. The average age of all patients was 64.2 years. A total of 5,960 cases (85.6 % of all photographs) were of adequate quality for the diagnosis. DR of any degree was found in 1,092 (18.3 %) patients. Normal fundus pictures were found in 49.4 % of patients. In 32.2 % of cases, non-DR pathologies were found. Among cases in which DR was found, 73.3 % (801 cases) had mild non-proliferative retinopathy (NPDR), 7.1 % (77 cases) had moderate NPDR, 6.8 % (74 cases) had proliferative retinopathy, and 12.8 % (140 cases) had diabetic macular edema. Older patients had more chance of having poor quality pictures (p < 0.001 between patients older and younger than 70 years). When non-mydriatic fundus photography was compared with dilated fundus examination by an ophthalmologist, sensitivity of 99.3 %, specificity of 88.3 %, and positive predictive value of 85.3 % were found. Non-mydriatic digital retinal photography is an efficient method for DR screening. The test has high sensitivity and specificity. The test, as performed in community health centers in the south of the country, contributed to the early diagnosis of >1,000 cases of DR. Many patients can be followed up in a fast and efficient way, although the test cannot replace a complete eye examination after pupil dilation mainly in older people. Other non-DR sight-threatening ocular pathologies can be also detected.

The incidental findings of age-related macular degeneration during diabetic retinopathy screening

BACKGROUND

The purpose of this study was to determine the reliability of detecting age-related macular degeneration (AMD) during screening for diabetic retinopathy (DR).

METHODS

This prospective study included 2,003 subjects with diabetes mellitus who underwent photographic screening for DR. The reliability of detecting AMD lesions was tested by interobserver and intraobserver agreement, and the sensitivity and specificity of diagnosing AMD at different grades of severity were tested using the consensus grading of a group as the reference standard.

RESULTS

DR affected 24.7% of the subjects. The age-standardized prevalence of early AMD was 17.9%, and late AMD was 0.1%. The interobserver and intraobserver agreement for grading AMD was substantial (k = 0.72 and 0.71 respectively, p < 0.001). It was equally good in those with different severities of DR. There was also no difference in sensitivity and specificity of detecting AMD in those with different levels of DR (sensitivity 62-68% and specificity 97-98%).

CONCLUSION

Intermediate- and high-risk AMD that warrant treatment with zinc and anti-oxidant supplements could be reliably detected during screening for diabetic retinopathy.

Ocular disease, knowledge and technology applications in patients with diabetes

An estimated 25.8 million children and adults in the United States, approximately 8.3% of the population, have diabetes. Diabetes prevalence varies by race and ethnicity. African Americans have the highest prevalence (12.6%), followed closely by Hispanics (11.8%), Asian Americans (8.4%) and whites (7.1%). The purpose of this article was to discuss the ocular complications of diabetes, the cultural and racial differences in diabetes knowledge and the role of telemedicine as a means to reach the undeserved who are at risk of complications. Information on the pathophysiology of ocular disease in patients with diabetes and the role of telemedicine in diabetes care was derived from a literature review. National Institutes of Health online resources were queried to present data on the racial and cultural understandings of diabetes and diabetes-related complications. The microvascular ocular complications of diabetes are discussed for retinopathy, cataracts, glaucoma and ocular surface disease. Racial and cultural differences in knowledge of recommended self-care practices are presented. These differences, in part, may explain health disparities and the increased risk of diabetes and its complications in rural minority communities. Finally, advances in telemedicine technology are discussed that show improvements in metabolic control and cardiovascular risk in adults with type 2 diabetes. Improving provider and patient understanding of diabetes complications may improve management and self-care practices that are important for diabetes control. Telemedicine may improve access to diabetes specialists and may improve self-management education and diabetes control particularly in rural and underserved communities.

Diabetic retinopathy screening: can the viewing monitor influence the reading and grading outcomes

PURPOSE

To evaluate the accuracy of different viewing monitors for image reading and grading of diabetic retinopathy (DR).

DESIGN

Single-centre, experimental case series-evaluation of reading devices for DR screening.

METHOD

A total of 100 sets of three-field (optic disc, macula, and temporal views) colour retinal still images (50 normal and 50 with DR) captured by FF 450 plus (Carl Zeiss) were interpreted on 27-inch iMac, 15-inch MacBook Pro, and 9.7-inch iPad. All images were interpreted by a retinal specialist and a medical officer. We calculated the sensitivity and specificity of 15-inch MacBook Pro and 9.7-inch iPad in detection of DR signs and grades with reference to the reading outcomes obtained using a 27-inch iMac reading monitor.

RESULTS

In detection of any grade of DR, the 15-inch MacBook Pro had sensitivity and specificity of 96% (95% confidence interval (CI): 85.1-99.3) and 96% (95% CI: 85.1-99.3), respectively, for retinal specialist and 91.5% (95% CI: 78.7-97.2) and 94.3% (95% CI: 83.3-98.5), respectively, for medical officer, whereas for 9.7-inch iPad, they were 91.8% (95% CI: 79.5-97.4) and 94.1% (95% CI: 82.8-98.5), respectively, for retinal specialist and 91.3% (95% CI: 78.3-97.1) and 92.6% (95% CI: 81.3-97.6), respectively, for medical officer.

CONCLUSION

The 15-inch MacBook Pro and 9.7-inch iPad had excellent sensitivity and specificity in detecting DR and hence, both screen sizes can be utilized to effectively interpret colour retinal still images for DR remotely in a routine, mobile or tele-ophthalmology setting. Future studies could explore the use of more economical devices with smaller viewing resolutions to reduce cost implementation of DR screening services.

Screening for diabetic retinopathy: review of current methods

OBJECTIVE

To review the current screening methods for diabetic retinopathy, with a focus on nonmydriatic digital fundus photography.

METHODS

Articles from Medline were reviewed from 1976 to November 2011 for different combinations of the words "diabetic retinopathy," "screening," "fundus photography," and "nonmydriasis."

RESULTS

Because of its ease of use and cost-effectiveness, digital fundus photography is becoming the preferred method for diagnosing diabetic retinopathy. Current research has proven that pupillary dilation is not a necessary step in the fundus examination, although it reduces the number of unnecessary referrals to ophthalmologists. Automated grading systems, while saving time and reducing human error, still need refinement before they can replace manual grading by trained ophthalmologists.

CONCLUSION

Nonmydriatic digital fundus photography with manual grading by a trained technician is an acceptable method of screening for diabetic retinopathy.

Incidence of diabetic retinopathy in people with type 2 diabetes mellitus attending the Diabetic Retinopathy Screening Service for Wales: retrospective analysis

OBJECTIVES

To determine the incidence of any and referable diabetic retinopathy in people with type 2 diabetes mellitus attending an annual screening service for retinopathy and whose first screening episode indicated no evidence of retinopathy.

DESIGN

Retrospective four year analysis.

SETTING

Screenings at the community based Diabetic Retinopathy Screening Service for Wales, United Kingdom.

PARTICIPANTS

57,199 people with type 2 diabetes mellitus, who were diagnosed at age 30 years or older and who had no evidence of diabetic retinopathy at their first screening event between 2005 and 2009. 49,763 (87%) had at least one further screening event within the study period and were included in the analysis.

MAIN OUTCOME MEASURES

Annual incidence and cumulative incidence after four years of any and referable diabetic retinopathy. Relations between available putative risk factors and the onset and progression of retinopathy.

RESULTS

Cumulative incidence of any and referable retinopathy at four years was 360.27 and 11.64 per 1000 people, respectively. From the first to fourth year, the annual incidence of any retinopathy fell from 124.94 to 66.59 per 1000 people, compared with referable retinopathy, which increased slightly from 2.02 to 3.54 per 1000 people. Incidence of referable retinopathy was independently associated with known duration of diabetes, age at diagnosis, and use of insulin treatment. For participants needing insulin treatment with a duration of diabetes of 10 years or more, cumulative incidence of referable retinopathy at one and four years was 9.61 and 30.99 per 1000 people, respectively.

CONCLUSIONS

Our analysis supports the extension of the screening interval for people with type 2 diabetes mellitus beyond the currently recommended 12 months, with the possible exception of those with diabetes duration of 10 years or more and on insulin treatment.

Light and portable novel device for diabetic retinopathy screening

BACKGROUND

To validate the use of an economical portable multipurpose ophthalmic imaging device, EyeScan (Ophthalmic Imaging System, Sacramento, CA, USA), for diabetic retinopathy screening.

DESIGN

Evaluation of a diagnostic device.

PARTICIPANTS

One hundred thirty-six (272 eyes) were recruited from diabetic retinopathy screening clinic of Royal Perth Hospital, Western Australia, Australia.

METHODS

All patients underwent three-field (optic disc, macular and temporal view) mydriatic retinal digital still photography captured by EyeScan and FF450 plus (Carl Zeiss Meditec, North America) and were subsequently examined by a senior consultant ophthalmologist using the slit-lamp biomicroscopy (reference standard). All retinal images were interpreted by a consultant ophthalmologist and a medical officer.

MAIN OUTCOME MEASURES

The sensitivity, specificity and kappa statistics of EyeScan and FF450 plus with reference to the slit-lamp examination findings by a senior consultant ophthalmologist.

RESULTS

For detection of any grade of diabetic retinopathy, EyeScan had a sensitivity and specificity of 93 and 98%, respectively (ophthalmologist), and 92 and 95%, respectively (medical officer). In contrast, FF450 plus images had a sensitivity and specificity of 95 and 99%, respectively (ophthalmologist), and 92 and 96%, respectively (medical officer). The overall kappa statistics for diabetic retinopathy grading for EyeScan and FF450 plus were 0.93 and 0.95 for ophthalmologist and 0.88 and 0.90 for medical officer, respectively.

CONCLUSIONS

Given that the EyeScan requires minimal training to use and has excellent diagnostic accuracy in screening for diabetic retinopathy, it could be potentially utilized by the primary eye care providers to widely screen for diabetic retinopathy in the community.

[Diabetic retinopathy: comparison of the diagnostic features of ultra-widefield scanning laser ophthalmoscopy Optomap with ETDRS 7-field fundus photography]

OBJECTIVE

The aim of the study was to compare the diagnostic properties of a non-mydriatic 200° ultra-widefield scanning laser ophthalmoscope (SLO) with mydriatic ETDRS 7-field fundus photography for diabetic retinopathy screening.

METHODS

A consecutive series of 66 eyes from 34 patients with different levels of diabetic retinopathy (DR) were examined. Grading of DR and macular edema (ME) obtained from mydriatic ETDRS 7-field fundus photography were compared with grading obtained from Optomap Panoramic 200MA SLO images. All SLOs were performed with an undilated pupil and no additional clinical information was used for evaluation of images by two independent, masked experts.

RESULTS

A total of 14 eyes from ETDRS 7-field fundus photography and 11 eyes from Optomap could not be graded by at least one grader due to poor image quality, yielding 48 eyes for comparison purposes. Of the 48 ETDRS 7-field fundus photographs, 9 (11 for grader 2) eyes had no or mild DR (ETDRS levels ≤20) and 17 (23 for grader 2) eyes had no ME. Agreement of Optomap retinopathy grading with ETDRS 7-field fundus photography was good, kappa 0.70 for grader 1 and kappa 0.66 for grader 2. There was good agreement between both techniques for ME, grader 1 kappa 0.68 and grader 2 kappa 0.74.

CONCLUSIONS

Grading of DR levels from Optomap Panoramic 200MA non-mydriatic images showed a good correlation with mydriatic ETDRS 7-field fundus photography. Both techniques are of sufficient quality for a valid assessment of DR. Optomap Panoramic 200MA images cover a larger retinal area and might therefore offer additional diagnostic properties.

Agreement and reasons for disagreement between photographic and hospital biomicroscopy grading of diabetic retinopathy

AIMS

To compare agreement level and identify reasons for disagreement between grading of mydriatic digital photographs in a diabetic retinopathy screening service and hospital eye service biomicroscopy grading.

METHODS

Structured examination findings leading to automatically calculated National Screening Committee grades recorded on an electronic medical record system in the hospital eye service at the first clinic visit after diabetic retinopathy screening service referral between April 2006 and November 2007 were retrospectively compared with the grade at the screening visit that prompted referral. In cases of disagreement, screening images were reviewed.

RESULTS

Data on 452 eyes (226 patients) were analysed. For retinopathy, hospital eye service slit-lamp biomicroscopy grades were: R0 (no diabetic retinopathy) in 63 eyes; R1 (background retinopathy) in 251 eyes; R2 (pre-proliferative) in 129 eyes and R3 (proliferative) in nine eyes. Diabetic retinopathy screening service grades were in agreement in 350 eyes (77.4%), showed a lower grade in 59 eyes and a higher grade in 43. Agreement was moderate (κ=0.60). The most common reason for disagreement was overgrading of R1 by clinicians. Hospital eye service biomicroscopy maculopathy grades were: M0 (no maculopathy) in 366 eyes and M1 (maculopathy) in 86 eyes. Diabetic retinopathy screening service grades were in agreement in 327 eyes (72.3%), showed a lower grading in five eyes and a higher grade in 120 eyes. Agreement was moderate (κ=0.41). The commonest cause for disagreement was clinicians failing to identify fine macular exudates.

CONCLUSIONS

This study of routine clinical services demonstrates moderate agreement between non-medical grading of mydriatic digital retinal photography images and hospital slit-lamp biomicroscopy grading of patients referred with diabetic retinopathy. The majority of errors in grading were attributable to errors by hospital doctors, usually in the direction of under-grading which could be a potential source of clinical risk if treatment is delayed.

Systematic review of the diagnostic accuracy of the single, two and three field digital retinal photography for screening diabetic retinopathy

BACKGROUND

Regular eye examinations are important to aid in early detection of diabetic retinopathy. Screening methods include ophthalmoscopy, retinal photography and variations of both. Digital retinal photography (DRP) is being increasingly adopted. The gold standard is to photograph seven visual fields, in practice, however, fewer fields such as single, two or three fields are used, to reduce cost and time. There is no existing review comparing the diagnostic accuracy of the single, two and three-field DRP.

OBJECTIVES

To perform a systematic review of the diagnostic accuracy of the single, two and three field DRP for screening diabetic retinopathy.

INCLUSION CRITERIA

All patients with diabetes mellitus who attended an eye screening were included. Studies which include digital retinal imaging techniques that capture single, two or three visual images were considered.To be included, studies must have compared the technique to a reference standard, either the seven-field stereoscopic fundus photography (7SF) or indirect ophthalmoscopy.

TYPES OF OUTCOMES

The main outcomes were sensitivity and specificity of the screening technique.

SEARCH STRATEGY

Search was carried out, for the time period 1985 to December 2008, for full text papers and conference abstracts.

METHODOLOGICAL QUALITY

Methodological quality of included studies was assessed by two reviewers using an adapted version of the critical appraisal tool for diagnostic studies developed by the Critical Appraisal Skills Programme at the Public Health Resource Unit.

DATA COLLECTION

Data from included studies were extracted using a modified JBI data extraction tool.

DATA SYNTHESIS

Studies were grouped by the reference standard used and summarised using tabular and narrative formats.

RESULTS

Twenty-two primary studies met the review criteria. Fifteen studies used a single field, five applied two-field and seven applied three-field. There was great heterogeneity among the studies. Using 7SF as a reference standard, the sensitivity (for detecting any retinopathy) of the single, two and three fields ranged from: 66%-87%, 86%-98%, and 66%-98%. For indirect ophthalmoscopy, sensitivity ranged from 38%-100%, 83%-97%, and 90%-97%. The corresponding specificity for 7SF was 45%-96%, 78%-95%, 72%-86%; for indirect ophthalmoscopy was 47%-100%, 79%-100%, 90%-98%. Five studies comparing more than one field type had a general trend of higher sensitivity and lower specificity with increasing number of fields. Pupil dilation led to a lower proportion of ungradeable images.

CONCLUSIONS

The review findings are limited by the heterogeneity between studies and the number of studies comparing more than one screening type. Evidence for the optimal number of screening fields is not conclusive.

IMPLICATIONS FOR PRACTICE

Until further research is available for stronger comparisons to be made, single field DRP would be the option requiring less time and lower costs. Dilation should be applied to reduce ungradeable images. Older age, smaller pupil size, and presence of cataract are associated with ungradeable images.

IMPLICATIONS FOR RESEARCH

There is a strong recommendation for field specialists to achieve consensus on DRP methods including a standard scale for grading diabetic retinopathy and common threshold for referrable retinopathy. Future studies should consider following the Standards for Reporting of Diagnostic Accuracy (STARD). A prospective study comparing the single, two and three fields, with and without dilation will provide the required evidence for optimal number of fields.

Trends in yield and effects of screening intervals during 17 years of a large UK community-based diabetic retinopathy screening programme

AIMS

To describe changes in risk profiles and yield in a screening programme and to investigate relationships between retinopathy prevalence, screening interval and risk factors.

METHODS

We analysed a population of predominantly Type 2 diabetic patients, managed in general practice, and screened between 1990 and 2006, with up to 17 years' follow-up and up to 14 screening episodes each. We investigated associations between referable or sight-threatening diabetic retinopathy (STDR), screening interval and frequency of repeated screening, whilst adjusting for age, duration and treatment of diabetes, hypertension treatment and period.

RESULTS

Of 63 622 screening episodes among 20 788 people, 16 094 (25%) identified any retinopathy, 3136 (4.9%) identified referable retinopathy and 384 (0.60%) identified STDR. The prevalence of screening-detected STDR decreased by 91%, from 1.7% in 1991-1993 to 0.16% in 2006. The prevalence of referable retinopathy increased from 2.0% in 1991-1993 to 6.7% in 1998-2001, then decreased to 4.7% in 2006. Compared with screening intervals of 12-18 months, screening intervals of 19-24 months were not associated with increased risk of referable retinopathy [adjusted odds ratio 0.93, 94% confidence interval (CI) 0.82-1.05], but screening intervals of more than 24 months were associated with increased risk (odds ratio 1.56, 95% CI 1.41-1.75). Screening intervals of < 12 months were associated with high risks of referable retinopathy and STDR.

CONCLUSIONS

Over time the risk of late diagnosis of STDR decreased, possibly attributable to earlier diagnosis of less severe retinopathy, decreasing risk factors and systematic screening. Screening intervals of up to 24 months should be considered for lower risk patients.

Comparison of dilated fundus examinations with seven-field stereo fundus photographs in the Veterans Affairs Diabetes Trial

OBJECTIVE

The Veterans Affairs Diabetes Trial (VADT) is a 20-medical center, prospective, randomized study of 1792 Type 2 diabetic individuals primarily aimed at determining whether intensive glycemic control prevents macrovascular events. We report a comparison of fundus photographs and ophthalmologic examination at baseline, permitting an evaluation of multiple settings similar to common clinical practice.

RESEARCH DESIGN AND METHODS

A 340-patient subset had both local dilated fundus examinations and centrally read seven-field stereo fundus photographs completed within 60 days of each other (median 28 days). Local examiners were unaware of the stereo photographs.

RESULTS

Overall, agreement within one step was 76% and exact agreement between ophthalmoscopy and central gradings of fundus photographs on a five-step retinopathy severity scale was 43% (weighted kappa 0.42, CI 0.35-0.48). In about 90% of disagreements the severity level was higher by photographic grading. The sensitivity for ophthalmoscopy compared to grading of fundus photographs for the detection of any retinopathy was 51% and specificity was 91%. For proliferative diabetic retinopathy (PDR), sensitivity was 61% and specificity 98%. Only one eye was high-risk PDR, and it was detected by both methods. For clinically significant macular edema, these measures were 24% and 98%, respectively. The disagreements were of possible clinical importance in three cases (<1%).

CONCLUSION

Most disagreements occurred in eyes rated near the milder end of a category and/or resulted from small differences between the ophthalmoscopic and photographic definitions used in classifying severity. There were reasonably few disagreements of possible clinical significance.

Screening for diabetic retinopathy: 1 and 3 nonmydriatic 45-degree digital fundus photographs vs 7 standard early treatment diabetic retinopathy study fields

PURPOSE

To evaluate if simple- or multiple-field digital color nonmydriatic (NM) retinal images can replace 7 standard stereoscopic fundus photographs in the screening of diabetic retinopathy (DR).

DESIGN

Prospective, masked, comparative case series.

METHODS

One hundred and eight eyes of 55 diabetics were studied to determine single lesions and to grade clinical levels of DR and diabetic macular edema (DME) using both 1 and 3 NM digital color retinal images compared with the Early Treatment Diabetic Retinopathy Study (ETDRS) 7 standard 35-mm stereoscopic color fundus photographs (7F-ETDRS). All eyes underwent NM 45-degree field images of 1 central field (1F-NM), NM 45-degree field images of 3 fields (3F-NM), and, after pupil dilatation, 30-degree 7F-ETDRS photography. Images were analyzed by 2 independent, masked retinal specialists (S.V. and E.B.), lesion-by-lesion according to the ETDRS protocol and for clinical severity level of DR and DME according to the international classification of DR.

RESULTS

Using 7F-ETDRS as the gold standard, agreement was substantial for grading clinical levels of DR and DME (kappa = 0.69 and kappa = 0.75) vs 3F-NM; moderate for DR level (kappa = 0.56) and substantial for DME (kappa = 0.66) vs 1F-NM; almost perfect for detecting presence or absence of DR (kappa = 0.88) vs both 1F-NM and 3F-NM; and almost perfect for presence or absence of DME (kappa = 0.97) vs 3F-NM and substantial (kappa = 0.75) vs 1F-NM. Sensitivity and specificity for detecting referable levels of DR were 82% and 92%, respectively, for 3F-NM and 71% and 96%, respectively, for 1F-NM.

CONCLUSIONS

Three color 45-degree NM fundus fields may be an effective tool in a screening setting to determine critical levels of DR and DME for prompt specialist referral. One central 45-degree image is sufficient to determine absence or presence of DR and DME, but not for grading it.

Diabetic retinopathy and socioeconomic deprivation in Gloucestershire

OBJECTIVES

To investigate socioeconomic variations in diabetes prevalence, uptake of screening for diabetic retinopathy, and prevalence of diabetic retinopathy.

METHODS

The County of Gloucestershire formed the setting of the study. A cross-sectional study of people with diabetes was done on a countywide retinopathy-screening database. Diabetes prevalence with odds ratios, uptake of screening, prevalence of any retinopathy and prevalence of sight-threatening retinopathy at screening were compared for different area deprivation quintiles. Logistic regression was used to adjust for confounding.

RESULTS

With each increasing quintile of deprivation, diabetes prevalence increased (odds ratio 0.84), the probability of having been screened for diabetic retinopathy decreased (odds ratio 1.11), and the prevalence of sight-threatening diabetic retinopathy among screened patients increased (odds ratio of 0.98), while the prevalence of non-sight-threatening diabetic retinopathy remained unchanged with each increasing quintile of deprivation.

CONCLUSION

Sight-threatening diabetic retinopathy was associated with socioeconomic deprivation, but non-sight-threatening diabetic retinopathy was not. Uptake of screening was inversely related to socioeconomic deprivation.

Screening uptake in a well-established diabetic retinopathy screening program: the role of geographical access and deprivation

OBJECTIVE

To identify criteria that affect uptake of diabetes retinal screening in a community screening program using mobile retinal digital photography units.

RESEARCH DESIGN AND METHODS

Data from the regional diabetes population-based retinal screening program and regional ophthalmology laser database were linked to patient postal code (zip code) data. We used distance from retinal screening event, social deprivation scores, and demographic information to identify risk factors for nonattendance at a diabetes retinal screening event. Patients were subdivided into urban (>125,000 population), other urban (3,000-125,000 population), or rural (<3,000 population) depending on where they lived. Data were collected from 2004 to 2006 inclusive and included 15,150 patients and 32,621 eye screening records.

RESULTS

The mean +/- SD age of patients was 63 +/- 15 years, and 54% were male. Mean travel time to retinal screening event varied from 7.1 to 17.0 min. For 12% of missed appointments, patients were more likely to be younger, to have longer diabetes duration, to have poor A1C and blood pressure control, to be smokers, and to live in deprived areas. Poor attendance was not associated with sex or distance to retinal screening event.

CONCLUSIONS

Social deprivation is strongly associated with poor attendance at retinal screening events. Time traveled to screening event was not associated with attendance in this study of a mobile retinal screening service, which visited general practitioner surgeries. This data can help inform population-based diabetes retinal screening programs about improving patient uptake.

OPHDIAT: a telemedical network screening system for diabetic retinopathy in the Ile-de-France

OBJECTIVE

International and national guidelines recommend an annual funduscopic examination for all diabetic patients, but such annual fundus examinations are not sufficiently performed in France. Non-mydriatic fundus photography is a valid method of evaluation for diabetic retinopathy (DR) and a viable alternative to ophthalmoscopy. After two pilot studies demonstrated the feasibility of telemedical screening for diabetic retinopathy in both hospital and primary-care settings, we developed a regional telemedical network, OPHDIAT, designed to facilitate access to regular annual evaluations of patients with diabetes while saving medical time.

MATERIALS AND METHODS

OPHDIAT comprises peripheral screening centres equipped with non-mydriatic cameras, where fundus photographs are taken by technicians linked by telemedicine to a reference centre, where ophthalmologists grade the images. Currently in the Ile-de-France region, 16 screening centres are linked through a central server to an ophthalmologic reading centre and includes 11 centres located in the diabetes departments of 11 hospitals, one diabetic retinopathy screening centre located in northern Paris, three in healthcare centres and one in a prison.

RESULTS

During the 28-month evaluation period, 15,307 DR screening examinations were performed. Retinal photographs of at least one eye could not be graded in 1332 patients (9.7%) and diabetic retinopathy was detected in 3350 patients (23.4%). After the screening examination, 3478 patients (25.2%) were referred to an ophthalmologist for either DR, cataract and/or non-gradable photographs.

CONCLUSION

Fundus photography combined with telemedicine has the potential to improve the regular annual evaluation for diabetic retinopathy. The organization of the network around a central reading centre serves to guarantee quality control.

[Validation of the electronic mailing of retinographs of diabetic patients in order to detect retinopathy in primary care]

OBJECTIVE

Evaluate concordance in biomicroscopy evaluation of diabetic retinopathy degree among ophthalmologists. Validation of e-mail transmission of digital fundus photographs of type 2 diabetes patients as a method of diabetic retinopathy detection.

DESIGN

Descriptive study.

SETTING

Urban, primary health centre, and hospital.

PARTICIPANTS

Type 2 diabetic patients selected of consecutive form when going to the primary health center (n=352).

MAIN MEASUREMENTS

Parallel observer-blind evaluation of degree of retinopathy through biomicroscopy performed by ophthalmologists, against digital photographic images sent by e-mail taken by the family doctors. Concordance in the biomicroscopy among ophthalmologists was previously tested.

RESULTS

Retinopathy was revealed in 25.70% of the retinographs; 10.44% was mild, 12.05% moderate, and 3.21% severe. Weighted kappa was 0.876 for biomicroscopy concordance. Sensitivity in detecting retinopathy is 76.6% and specificity 95.2%; 92.7% and 99.5% for ophthalmologist-derivable retinopathy. Sensitivity was 66.7% for non-mydriatic retinograph without dilation, 76.9% with elective dilation, and 85% with the mydriatic.

CONCLUSIONS

Concordance in evaluation of retinopathy degree through biomicroscopy was "very good." This allows using a single ophthalmologist's exploration as a reference model. E-mail transmission of the photograph of the back of the eye in type 2 diabetic patients as a retinopathy detection method is feasible. Regardless of the type of retinograph used, the photographs should be taken on the dilated eye, as this significantly improves sensitivity.

Article Commentary: The English national screening programme for sight-threatening diabetic retinopathy

Objectives

The main objective of the national screening programme is to reduce the risk of sight loss among people with diabetes due to diabetic retinopathy (DR).

Methods

Offering two-field mydriatic digital photographic screening to all people with diabetes in England over the age of 12 years.

Stage of development

The programme is in its infancy, receiving the first year's annual reports from approximately 96 screening programmes, each of which have developed to offer screening to a minimum number of 12,000 people with diabetes, which would cover a population of 350,000 people with 3.4% diabetes prevalence. The national programme has commenced the External quality assurance (QA) programme in order to achieve and sustain the highest possible standards.

Potential benefits

England has a population of two million people with diabetes over the age of 12 and it is believed that there is a prevalence of blindness of 4200 and an annual incidence of blindness of 1280 people with diabetes. This programme has the potential to reduce the prevalence of blindness in England from 4200 people to 1000 people and a conservative estimate of reducing the annual incidence of DR blindness by one-third would save 427 people per annum from blindness. These figures are based on the UK certification of blindness but if World Health Organization (WHO) definitions are used the prevalence, incidence and potential reductions in blindness are much greater.

Prevalence of diabetic retinopathy in children and adolescents with type-1 diabetes attending summer camps in France

OBJECTIVE

To evaluate, using fundus photography, the prevalence of diabetic retinopathy (DR) in young diabetic subjects attending summer camps run by the Aide aux Jeunes Diabétiques Association (Aid to Young Diabetics).

RESEARCH DESIGN AND METHODS

Five hundred and four children and adolescents (250 boys and 254 girls), with type 1 diabetes mellitus, aged 10-18 years (mean:13+/-2), were screened for DR using non mydriatic photography, during their stay in a holiday camp. Demographic and clinical data recorded on subjects' arrival in the camp included date of birth, height, weight, treatment, blood pressure, and duration of diabetes. HbA(1c) was determined with a DCA 2000 kit.

RESULTS

Mean diabetes duration was 4.8+/-3.4 years and mean HbA(1c) was 8.5+/-1.3%. Mild non proliferative DR was diagnosed in 23 children (4.6%). Compared to subjects without DR, those with DR were significantly older (P<10(-3)), had a longer duration of diabetes (P=0.001), higher systolic blood pressure (P=0.04), and had higher (but not significantly so) HbA(1c) (P=0.15). After adjustment for age, only longer duration remained significantly associated with DR (P=0.01).

CONCLUSION

The prevalence of DR in these young patients was low compared to that reported in previous studies. The decrease may be due to modern diabetes care with multiple insulin injections. However, early detection of DR in adolescents, especially in their late teens, remains important, because it allows the identification of patients at high risk of progression towards severe stages of DR.

Accuracy of digital images for assessing diabetic retinopathy

BACKGROUND

To determine the accuracy of diabetic retinopathy status assessments with and without pupil dilation using digital fundus photographs acquired by a clinic staff person and interpreted remotely by ophthalmologists.

METHOD

Using early treatment diabetic retinopathy study (EDTRS) grading criteria, diabetic retinopathy status assessments were made by an experienced (nonphysician) retinal grader (NPG) based on seven standard field 35-mm stereoscopic slides acquired by an experienced ophthalmic photographer. These assessments were compared with those of the same eyes made by two ophthalmologists and the NPG using digital photographs acquired by a clinic staff person using a high-resolution (800 x 600) digital color camera system.

RESULTS

Based on 35-mm slides, 38% of 244 diabetic patients had ETDRS > or =35 in at least one eye and 5% had vision-threatening diabetic retinopathy (ETDRS > or =53 or macular edema). The proportion of ungradable images was significantly greater for nonmydriatic than mydriatic assessments (30% versus 10% ungradable as determined by the NPG). For ETDRS level > or =35, specificity ranged from moderate to high (0.70 to 0.96) for the three graders, while sensitivity was poor to moderate (0.38 to 0.71), and the area under the receiver-operating characteristic curves was less than satisfactory (0.67 to 0.71).

CONCLUSIONS

The low sensitivity of the digital assessments indicates a significant proportion of patients in need of referral would not have been referred. These findings suggest that implementation of a simplified screening system using nonphotographer clinic staff acquiring nonmydriatic images, with interpretation by an ophthalmologist, should take place with an understanding of potential limitations.

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.

Can we predict which patients are at risk of having an ungradeable digital image for screening for diabetic retinopathy?

PURPOSE

We aimed to determine the reasons for, and variables which predicted, ungradeable retinal photographs during screening patients for diabetic retinopathy.

MATERIALS AND METHODS

Age, duration of diabetes, visual acuity, and HbA1c were recorded. Following dark adaptation, a single 45 degrees nonmydriatic photograph was taken of each fundus. The pupils were then dilated and the photograph repeated. Using slit lamp biomicroscopy, lenticular changes (LOCS III), and fundus appearance were recorded.

RESULTS

In ungradeable photographs the fovea could not be visualised in 98% of cases of images from nonmydriatic photography, and in 88% if mydriasis was used. Poor definition in the nonmydriatic image was associated with a subsequent ungradeable mydriatic photograph (P=0.001), however, the positive predictive value was poor (34%). Age, posterior subcapsular cataract, and near vision predicted ungradeable status of nonmydriatic photographs (P<0.001, P=0.004, P=0.006, respectively; regression analysis). Nuclear colour and poor definition of the nonmydriatic photograph predicted ungradeable status of mydriatic photographs (P=0.006 & P=0.001, respectively).

CONCLUSION

Inability to visualise the fovea is the commonest cause of an ungradeable image from digital retinal photography. Age and posterior subcapsular cataract were best predictors of ungradeable status of nonmydriatic fundus photographs. Nuclear colour was the strongest predictor for ungradeable mydriatic photography.

Managing 'suspicious glaucomatous discs' identified during digital-photography-based diabetic retinopathy screening

PURPOSE

An audit to demonstrate the outcome of patients identified with suspicious glaucomatous discs within a digital-photography-based diabetic retinopathy screening programme.

METHODS

Primary care based digital photographic screening was performed utilising mydriasis and two-field digital photography for all patients with diabetes. Patients identified with discs suspicious of glaucomatous optic neuropathy (GON) were initially referred to an accredited community-based optometrist for further assessment. Some patients were then referred to secondary care where appropriate.

RESULTS

From 1st April 2002 to 31st March 2003 a total of 3868 patients were screened for diabetic retinopathy. This audit revealed that 55 subjects were identified by retinal screeners as having discs suspicious of glaucoma. A total of 29 were already under glaucoma clinic review. A total of 23/26 remaining were referred for an assessment by an accredited optometrist. Of these 13 were normal, 6 were referred to secondary care and 4 failed to attend. The three remaining were referred directly to secondary care.

CONCLUSIONS

All nine referrals to secondary care were deemed appropriate by a glaucoma specialist. This suggests that the system described does not lead to over-referral of suspicious discs - although the issue of how many glaucomatous discs are missed during screening (false negatives) will only be answered in the longer term.

The influence of age, duration of diabetes, cataract, and pupil size on image quality in digital photographic retinal screening

OBJECTIVE

To evaluate the effect of age, duration of diabetes, cataract, and pupil size on the image quality in digital photographic screening.

RESEARCH DESIGN AND METHODS

Randomized groups of 3,650 patients had one-field, non-mydriatic, 45 degrees digital retinal imaging photography before mydriatic two-field photography. A total of 1,549 patients were then examined by an experienced ophthalmologist. Outcome measures were ungradable image rates, age, duration of diabetes, detection of referable diabetic retinopathy, presence of early or obvious central cataract, pupil diameter, and iris color.

RESULTS

The ungradable image rate for non-mydriatic photography was 19.7% (95% CI 18.4-21.0) and for mydriatic photography was 3.7% (3.1-4.3). The odds of having one eye ungradable increased by 2.6% (1.6-3.7) for each extra year since diagnosis for nonmydriatic, by 4.1% (2.7-5.7) for mydriatic photography irrespective of age, by 5.8% (5.0-6.7) for non-mydriatic, and by 8.4% (6.5-10.4) for mydriatic photography for every extra year of age, irrespective of years since diagnosis. Obvious central cataract was present in 57% of ungradable mydriatic photographs, early cataract in 21%, no cataract in 9%, and 13% had other pathologies. The pupil diameter in the ungradable eyes showed a significant trend (P < 0.001) in the three groups (obvious cataract 4.434, early cataract 3.379, and no cataract 2.750).

CONCLUSIONS

The strongest predictor of ungradable image rates, both for non-mydriatic and mydriatic digital photography, is the age of the person with diabetes. The most common cause of ungradable images was obvious central cataract.

An evaluation of the change in activity and workload arising from diabetic ophthalmology referrals following the introduction of a community based digital retinal photographic screening programme

AIMS

To determine how the workload of an ophthalmology department changed following the introduction of an organised retinal screening programme.

METHODS

Information was collected from the hospital medical record of people with diabetes attending eye clinics over 4 years. The first year was before screening, the next 2 years the first round, and the fourth year the second round.

RESULTS

The total number of people with diabetes referred each year over the 4 year period was 853, 954, 974, 1051 consecutively. The number of people with diabetes in the county rose by 1400 per annum. The total number of referrals for an opinion about diabetic retinopathy was 227, 333, 363, 368, for cataract was 64, 57, 77, 93, and for glaucoma was 57, 62, 61, 68. The total number of patients referred for laser treatment over the 4 years was 77, 124, 111, and 63

CONCLUSION

This study suggests that the workload in the eye clinic increases in the first round of screening but in subsequent rounds it does not fall below the pre-screening level, except for laser treatment. This may be partly because of increasing numbers of people with diabetes. With the introduction of a national screening programme, this has significant workload implications for the National Health Service.

Rates of diabetes mellitus-related complications in a contemporary adolescent cohort

BACKGROUND

Ten years after the Diabetes Control and Complications Trial there is a paucity of data as to what are current rates of diabetes-related complications in adolescence.

OBJECTIVE

To assess the incidence of diabetes-related complications in a contemporary cohort of adolescents with type 1 diabetes mellitus.

DESIGN

Retrospective cross-sectional survey.

PATIENTS

Adolescents aged >10 years with type 1 diabetes mellitus for >5 years from the Royal Children's Hospital, Melbourne Diabetes Clinic.

RESULTS

382 patients were studied (191 male). The mean HbA1c for males was 8.72% and for females was 8.80%. The rates of hypothyroidism and hypercholesterolaemia were 1.5% and 22% respectively. Twenty-five patients (8%) had intermittent microalbuminuria and six (2%) had persistent microalbuminuria. Only one patient had macroalbuminuria (0.3%). Only two patients (0.7%) with mild non-were diagnosed proliferative diabetic retinopathy. Coeliac disease was diagnosed in 6% of patients.

CONCLUSIONS

In this representative and contemporary cohort of diabetic adolescents the incidence of microvascular diabetes-related complications is quite low.

A pilot quality assurance scheme for diabetic retinopathy risk reduction programmes

AIMS

We describe a pilot study of measurement of quality assurance targets for diabetic retinopathy screening and performance comparison between 10 existing services, in preparation for the roll-out of the national programme.

BACKGROUND

In 1999 the UK National Screening Committee approved proposals for a national diabetic retinopathy risk reduction programme, including recommendations for quality assurance, but implementation was held pending publication of the National Service Framework for Diabetes. Existing services requested the authors to perform a pilot study of a QA scheme, indicating willingness to contribute data for comparison.

METHODS

Objectives and quality standards were developed, following consultation with diabetologists, ophthalmologists and retinal screeners. Services submitted 2001/2 performance data, in response to a questionnaire, for anonymization, central analysis and comparison.

RESULTS

The 17 quality standards encompass all aspects of the programme from identification of patients to timeliness of treatment. Ten programmes took part, submitting all the data available. All returns were incomplete, but especially so from the optometry-based schemes. Eight or more services demonstrated they could reach the minimum level in only five of the 17 standards. Thirty per cent could not provide coverage data. All were running behind. Reasons for difficulties in obtaining data and/or failing to achieve standards included severe under-funding and little previous experience of QA. Information systems were limited and incompatible between diabetes and eye units, and there was a lack of co-ordinated management of the whole programme.

CONCLUSION

Quality assurance is time-consuming, expensive and inadequately resourced. The pilot study identified priorities for local action. National programme implementation must involve integral quality assurance mechanisms from the outset.

Photoscreening for diabetic retinopathy: a comparison of image quality between film photography and digital imaging

PURPOSE

Retinal images from patients attending an urban screening centre before and after the transition from film photography to digital image acquisition were analysed for quality of image.

METHODS

A total of 1946 diabetic patients, aged 12-92 years (mean 55.6 +/- 14.88 years), were included in this retrospective study of retinal screening techniques. Each imaging group was subdivided into age-matched groups. In all subjects pupils were pharmacologically dilated before photography. The images were reviewed by the same three experienced observers and graded at the time of screening from grade 1 (excellent quality) to grade 4 (unreadable).

RESULTS

Of 938 patients in the film group, 31.3% had excellent images, 38.2% good, 22.7% poor and 7.8% were unreadable. Of the 1008 patients in the digital imaging group, 25.3% had excellent images, 46.3% good, 14.6% poor and 13.8% were unreadable. A significant difference was observed in patients over 65 years of age who exhibited a threefold increase in failure rate with digital imaging (33.7% v 11.3%)(P < 0.0001).

CONCLUSION

In this study population a statistically significant degradation of image quality was observed in those older than 65 years following transition to digital photography. This has implications for service provision planning.

Effect of mydriasis and different field strategies on digital image screening of diabetic eye disease

AIMS

To assess the effects of (1) mydriasis and (2) single versus three field photography on screening for diabetic eye disease using digital photography

METHOD

Slit lamp examination findings were compared to digital fundal photographs for the detection of any retinopathy and for referable retinopathy in 398 patients (794 eyes). A Topcon TRC-NW6S digital non-mydriatic fundus camera was used. Three photographic strategies were used: undilated single field, dilated single field, and dilated multiple fields. The photographs were presented in random order to one of two retinal screeners. For the single field photographs the screeners were masked to the use of mydriatics. In 13% of fundal photographs, grading was performed by both, rather than just one grader.

RESULTS

Mydriasis reduced the proportion of ungradable photographs from 26% to 5% (p<0.001). Neither mydriasis nor three field photography improved the sensitivity or specificity for the detection of any retinopathy or of referable retinopathy when compared with undilated single field photography. The sensitivity and specificity for detecting referable retinopathy using undilated single field photography was 77% (95% CI 71 to 84) and 95 % (95% CI 93 to 97) respectively. Using dilated single field photography the figures were 81% (95% CI 76 to 87) and 92% (95% CI 90 to 94) respectively. Using dilated three field photography the figures were 83% (95% CI 78 to 88) and 93% (95% CI 91 to 96) respectively. Intergrader reliability for the detection of referable retinopathy in gradable photographs was excellent (Kappa values 0.86-1.00).

CONCLUSIONS

Mydriasis reduces the technical failure rate. Mydriasis and the three field photography as used in this study do not increase the sensitivity or specificity of detecting diabetic retinopathy.

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.