Systematic screening for diabetic eye disease in insulin dependent diabetes

Teleophthalmology and retina: a review of current tools, pathways and services

Telemedicine, the use of telecommunication and information technology to deliver healthcare remotely, has evolved beyond recognition since its inception in the 1970s. Advances in telecommunication infrastructure, the advent of the Internet, exponential growth in computing power and associated computer-aided diagnosis, and medical imaging developments have created an environment where telemedicine is more accessible and capable than ever before, particularly in the field of ophthalmology. Ever-increasing global demand for ophthalmic services due to population growth and ageing together with insufficient supply of ophthalmologists requires new models of healthcare provision integrating telemedicine to meet present day challenges, with the recent COVID-19 pandemic providing the catalyst for the widespread adoption and acceptance of teleophthalmology. In this review we discuss the history, present and future application of telemedicine within the field of ophthalmology, and specifically retinal disease. We consider the strengths and limitations of teleophthalmology, its role in screening, community and hospital management of retinal disease, patient and clinician attitudes, and barriers to its adoption.

Building a new regional home for implementation science: Annual Midwest Clinical & Translational Research Meetings

The vision of the Central Society for Clinical and Translational Research (CSCTR) is to "promote a vibrant, supportive community of multidisciplinary, clinical, and translational medical research to benefit humanity." Together with the Midwestern Section of the American Federation for Medical Research, CSCTR hosts an Annual Midwest Clinical & Translational Research Meeting, a regional multispecialty meeting that provides the opportunity for trainees and early-stage investigators to present their research to leaders in their fields. There is an increasing national and global interest in implementation science (IS), the systematic study of activities (or strategies) to facilitate the successful uptake of evidence-based health interventions in clinical and community settings. Given the growing importance of this field and its relevance to the goals of the CSCTR, in 2022, the Midwest Clinical & Translational Research Meeting incorporated new initiatives and sessions in IS. In this report, we describe the role of IS in the translational research spectrum, provide a summary of sessions from the 2022 Midwest Clinical & Translational Research Meeting, and highlight initiatives to complement national efforts to build capacity for IS through the annual meetings.

Visual acuity and causes of central visual loss in the adult Danish population 2020-2022. Results from the FORSYN study

PURPOSE

Knowledge of visual health in the population is necessary for designing and implementing measures to handle visual handicap. The purpose of the FORSYN (Forekomst af synshandicap og synshjaelpemidler i Danmark) project was to study visual health in the Danish population 2020-2022 after implementation of the recent advances in the management of choroidal and retinal vascular disease. The present study reports visual acuity and causes of central visual loss from this study.

METHODS

A population-representative sample of 10 350 citizens living within 40 kilometres from Aarhus University Hospital were invited to answer a questionnaire about quality of life related to vision, measurement of visual acuity and a non-mydriatic examination of the eyes. The data were corrected for selection bias on the basis of demographic and socioeconomic factors so that the results could be projected to represent the adult Danish population.

RESULTS

Population-adjusted visual acuity in ETDRS letters (mean ± SD) differed significantly (p < 0.0001) among the worse eye (84.1 ± 0.25), the better eye (88.4 ± 0.11) and binocularly (89.2 ± 0.15). Social blindness affected 0.22% (95% CI: 0.14%-0.33%) of the population and was in none of the studied persons due to exudative age-related macular degeneration (AMD) or diabetic retinopathy. The most frequent causes of visual loss were atrophic AMD, neuro-ophthalmic disorders and other chorioretinal diseases.

CONCLUSIONS

Recent advances in the therapy of chorioretinal vascular diseases have been paralleled with a reduction in central vision loss secondary to exudative AMD and diabetic retinopathy in Denmark. The demographic development can be expected to increase the demand for treatments of vision-threatening diseases that mainly affect older persons.

Diabetic Retinopathy Screening and Registration in Europe-Narrative Review

Diabetic retinopathy (DR) is a leading cause of preventable vision impairment and blindness in the European Region. Despite the fact that almost all European countries have some kind of prophylactic eye examination for people with diabetes, the examinations are not properly arranged and are not organized according to the principles of screening in medicine. In 2021, the current COVID-19 pandemic moved telemedicine to the forefront healthcare services. Due to that, a lot more patients could benefit from comfortable and faster access to ophthalmology specialist care. This study aimed to conduct a narrative literature review on current DR screening programs and registries in the European Union for the last 20 years. With the implementation of telemedicine in daily medical practice, performing screening programs became much more attainable. Remote assessment of retinal pictures simultaneously saves countries time, money, and other resources.

The Evolution of Diabetic Retinopathy Screening Programmes: A Chronology of Retinal Photography from 35 mm Slides to Artificial Intelligence

As a third of people with diabetes mellitus (DM) will suffer the microvascular complications of diabetic retinopathy (DR) and therapeutic options can effectively prevent visual impairment, systematic screening has substantially reduced disease burden in developed countries. In an effort to tackle the rising incidence of DM, screening programmes have modernized in synchrony with technical and infrastructural advancements. Patient evaluation has shifted from face-to-face ophthalmologist-based review delivered through community grassroots to asynchronous store-and-forward modern telemedicine platforms commissioned on a nationwide scale. First pioneered with primitive 35-mm slide film retinal photography, the last decade has seen an emergence of high resolution and widefield imaging devices, which may reveal extents of DR indiscernible to the clinician but with implications of potential earlier identification. Similar progress has been seen in image analysis approaches - automated image analysis of retinal photographs of DR has evolved from qualitative feature detection to rules-based algorithms to autonomous artificial intelligence-powered classification. Such models have, relatively rapidly, been validated and are now receiving approval from health regulation authorities with deployment into the clinical sphere. In this review, we chart the evolution of global DR screening programmes since their inception highlighting major milestones in healthcare infrastructure, telemedicine approaches and imaging devices that have shaped the robust and effective frameworks recognised today. We also provide an outlook for the future of DR screening in the context of recent technological advancements with respect to their limitations in current times.

Screening Intervals for Diabetic Retinopathy and Implications for Care

PURPOSE OF REVIEW

The purpose of this study is to review the evidence that lower risk groups who could safely be screened less frequently for sight-threatening diabetic retinopathy (DR) than annually.

RECENT FINDINGS

Data have demonstrated that people with no DR in either eye are at a low risk of progression to sight-threatening DR over a 2-year period (event rate 4.8 per 1000 person years), irrespective of whether the screening method is one-field non-mydriatic or two-field mydriatic digital photography. Low risk has been defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with risk factor data. The risk of an extension to 2 years is less than 5 per 1000 person years in a population with a national screening programme, and the general standard of diabetes care is relatively good, whether low risk is defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with other risk factor data. The definition used in different populations is likely to depend on the availability of data.

The Diabetic Retinopathy Screening Workflow: Potential for Smartphone Imaging

Complications of diabetes mellitus, namely diabetic retinopathy and diabetic maculopathy, are the leading cause of blindness in working aged people. Sufferers can avoid blindness if identified early via retinal imaging. Systematic screening of the diabetic population has been shown to greatly reduce the prevalence and incidence of blindness within the population. Many national screening programs have digital fundus photography as their basis. In the past 5 years several techniques and adapters have been developed that allow digital fundus photography to be performed using smartphones. We review recent progress in smartphone-based fundus imaging and discuss its potential for integration into national systematic diabetic retinopathy screening programs. Some systems have produced promising initial results with respect to their agreement with reference standards. However further multisite trialling of such systems' use within implementable screening workflows is required if an evidence base strong enough to affect policy change is to be established. If this were to occur national diabetic retinopathy screening would, for the first time, become possible in low- and middle-income settings where cost and availability of trained eye care personnel are currently key barriers to implementation. As diabetes prevalence and incidence is increasing sharply in these settings, the impact on global blindness could be profound.

Prevalence of diabetic retinopathy within a national diabetic retinopathy screening service

AIMS

Determine the prevalence and severity of diabetic retinopathy (DR) and risk factors in a large community based screening programme, in order to accurately estimate the future burden of this specific and debilitating complication of diabetes.

METHODS

A cross-sectional analysis of 91,393 persons with diabetes, 5003 type 1 diabetes and 86,390 type 2 diabetes, at their first screening by the community based National Diabetic Retinopathy Screening Service for Wales from 2005 to 2009. Image capture used 2×45° digital images per eye following mydriasis, classified by qualified retinal graders with final grading based on the worst eye.

RESULTS

The prevalence of any DR and sight-threatening DR in those with type 1 diabetes was 56.0% and 11.2%, respectively, and in type 2 diabetes was 30.3% and 2.9%, respectively. The presence of DR, non-sight-threatening and sight-threatening, was strongly associated with increasing duration of diabetes for either type 1 or type 2 diabetes and also associated with insulin therapy in those with type 2 diabetes.

CONCLUSIONS

Prevalence of DR within the largest reported community-based, quality assured, DR screening programme, was higher in persons with type 1 diabetes; however, the major burden is represented by type 2 diabetes which is 94% of the screened population.

Inflammation and pharmacological treatment in diabetic retinopathy

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, is estimated to be the leading cause of new blindness in the working population of developed countries. Primary interventions such as intensive glycemic control, strict blood pressure regulation, and lipid-modifying therapy as well as local ocular treatment (laser photocoagulation and pars plana vitrectomy) can significantly reduce the risk of retinopathy occurrence and progression. Considering the limitations of current DR treatments development of new therapeutic strategies, it becomes necessary to focus on pharmacological treatment. Currently, there is increasing evidence that inflammatory processes have a considerable role in the pathogenesis of DR with multiple studies showing an association of various systemic as well as local (vitreous and aqueous fluid) inflammatory factors and the progression of DR. Since inflammation is identified as a relevant mechanism, significant effort has been directed to the development of new concepts for the prevention and treatment of DR acting on the inflammatory processes and the use of pharmacological agents with anti-inflammatory effect. Inhibiting the inflammatory pathway could be an appealing treatment option for DR in future practices, and as further prospective randomized clinical trials accumulate data, the role and guidelines of anti-inflammatory pharmacologic treatments will become clearer.

Prevalence of diabetic retinopathy in various ethnic groups: a worldwide perspective

The alarming rise in diabetes prevalence is a global public health and economic problem. Diabetic retinopathy is the most common complication of diabetes and the leading cause of blindness among working-age populations in the Western world. Screening and prompt treatment of diabetic retinopathy are not top priorities in many regions of the world, because the impacts of other causes of preventable blindness remain an issue. Ethnicity is a complex, independent risk factor for diabetic retinopathy. Observations from white populations cannot be extrapolated fully to other ethnic groups. The prevalence of diabetic retinopathy, sight-threatening diabetic retinopathy, and clinically significant macular edema are higher in people of South Asian, African, Latin American, and indigenous tribal descent compared to the white population. Although all ethnic groups are susceptible to the established risk factors of diabetic retinopathy-such as length of exposure and severity of hyperglycemia, hypertension, and hyperlipidemia-ethnic-specific risk factors also may influence these rates. Such risk factors may include differential susceptibility to conventional risk factors, insulin resistance, differences in anthropometric measurements, truncal obesity, urbanization, variations in access to healthcare systems, genetic susceptibility, and epigenetics. The rates of nonproliferative diabetic retinopathy appear to be declining in the United States, supporting the observation that better medical management of diabetes and prompt treatment of sight-threatening diabetic retinopathy substantially improve the long-term diabetic retinopathy incidence; studies from other parts of the world are limited and do not mirror this finding, however. We examine the ethnicity and region-based prevalence of diabetic retinopathy around the world and highlight the need to reinforce ethnicity-based screening and treatment thresholds in diabetic retinopathy.

Individual risk assessment and information technology to optimise screening frequency for diabetic retinopathy

AIMS/HYPOTHESIS

The aim of this study was to reduce the frequency of diabetic eye-screening visits, while maintaining safety, by using information technology and individualised risk assessment to determine screening intervals.

METHODS

A mathematical algorithm was created based on epidemiological data on risk factors for diabetic retinopathy. Through a website, www.risk.is , the algorithm receives clinical data, including type and duration of diabetes, HbA(1c) or mean blood glucose, blood pressure and the presence and grade of retinopathy. These data are used to calculate risk for sight-threatening retinopathy for each individual's worse eye over time. A risk margin is defined and the algorithm recommends the screening interval for each patient with standardised risk of developing sight-threatening retinopathy (STR) within the screening interval. We set the risk margin so that the same number of patients develop STR within the screening interval with either fixed annual screening or our individualised screening system. The database for diabetic retinopathy at the Department of Ophthalmology, Aarhus University Hospital, Denmark, was used to empirically test the efficacy of the algorithm. Clinical data exist for 5,199 patients for 20 years and this allows testing of the algorithm in a prospective manner.

RESULTS

In the Danish diabetes database, the algorithm recommends screening intervals ranging from 6 to 60 months with a mean of 29 months. This is 59% fewer visits than with fixed annual screening. This amounts to 41 annual visits per 100 patients.

CONCLUSION

Information technology based on epidemiological data may facilitate individualised determination of screening intervals for diabetic eye disease. Empirical testing suggests that this approach may be less expensive than conventional annual screening, while not compromising safety. The algorithm determines individual risk and the screening interval is individually determined based on each person's risk profile. The algorithm has potential to save on healthcare resources and patients' working hours by reducing the number of screening visits for an ever increasing number of diabetic patients in the world.

Risk of retinal neovascularization in the second eye in patients with proliferative diabetic retinopathy

PURPOSE

This study aimed to evaluate the risk of proliferative diabetic retinopathy (DR) in the fellow eye of an eye with existing proliferative DR.

METHODS

Our DR screening programme database listed 1513 diabetes patients alive at the time of the study. Seventy-six had proliferative DR in one or both eyes.

RESULTS

In 28 of the 76 (37%) diabetes patients, proliferative DR was diagnosed in both eyes at the same examination. Another 28 patients developed proliferative DR in the second eye within 5 years of its diagnosis in the first eye, bringing the total number of diabetes patients with proliferative DR in both eyes at 5 years to 56 (74%). Almost all the diabetes patients eventually developed proliferative DR in the second eye. The median duration of diabetes before the development of proliferative retinopathy was 19 years for type 1 and 14 years for type 2 diabetes.

CONCLUSIONS

Proliferative DR is a bilateral disease. Diabetes patients with proliferative DR in one eye are at high risk of developing neovascularization in the second eye and close follow-up is recommended.

Biennial eye screening in patients with diabetes without retinopathy: 10-year experience

AIMS

To evaluate the safety of every-other-year eye screening for patients with diabetes without retinopathy.

METHODS

Since 1994, patients with diabetes without retinopathy in Iceland have received eye screening every other year. 296 patients with diabetes who had no diabetic retinopathy in 1994/95 were followed with biennial eye examinations until they had developed retinopathy. The 10-year experience of this approach is reviewed.

RESULTS

Out of the 296 diabetic individuals, 172 did not develop diabetic retinopathy during the 10-year observation period. 96 patients developed mild non-proliferative retinopathy, six developed clinically significant diabetic macular oedema, 23 developed preproliferative retinopathy, and four developed proliferative diabetic retinopathy during the 10-year observation period. All the patients who developed macular oedema or proliferative retinopathy had already been diagnosed as having mild nonproliferative retinopathy and entered an annual screening protocol before the sight-threatening retinopathy developed. No patient had any undue delay in treatment.

CONCLUSION

Every other year screening for diabetic eye disease seems to be safe and effective in diabetics without retinopathy. Such an approach will reduce the number of screening visits more than 25%. This reduces health costs and strain on resources considerably and relieves the patients with diabetes from unnecessary clinic visits and examinations.

Screening compliance and visual outcome in diabetes

PURPOSE

To study the relationship between screening compliance and visual outcome in a screening programme for diabetic eye disease.

METHODS

A retrospective case control study. The screening compliance of all the diabetes patients (n = 22) listed at the Icelandic National Registry for the Blind (visual acuity <0.3) was compared to a matched group of 44 non-blind diabetes patients (visual acuity > or =0.3) who participated in the same screening programme for diabetic retinopathy. Glycaemic control (HbA1c), office blood pressure and cholesterol levels were assessed.

RESULTS

The study group had a significantly lower level of compliance with the screening programme (27% +/- 38% [mean +/- SD] versus 77% +/- 26% [mean +/- SD]; p < 0.0001). Macular oedema or proliferative diabetic retinopathy was found in 60% (13/22) of the study group when entering the screening programme, compared to 7% (3/44) in the control group. Blood pressure (except diastolic BP among type 1 diabetes mellitus), blood glucose and cholesterol levels were identical. The prevalence of blindness and low vision amongst diabetes patients in Iceland is about 0.5%.

CONCLUSIONS

There was a significant relationship between screening compliance and visual outcome in diabetes patients in our screening programme.

Unchanged incidence of diabetic nephropathy in Type 1 diabetes: a nation-wide study in Iceland

AIMS

Diabetic nephropathy is an uncommon cause of end-stage renal disease in Iceland in contrast to most industrialized countries. The aim of this study was to examine the incidence of diabetic nephropathy in Iceland.

METHODS

All patients diagnosed with Type 1 diabetes in Iceland before 1992 were studied retrospectively. Patients diagnosed before age 30, who were insulin dependent from the onset, were defined as having Type 1 diabetes. Diabetic nephropathy was defined as persistent proteinuria measured with a dipstick test (Albustix) on three consecutive clinic visits at least 2 months apart. Patients were followed to the end of year 1998, to their last recorded outpatient visit, or until death. The cumulative incidence of diabetic nephropathy was calculated with the Kaplan-Meier method and presented according to the duration of diabetes divided into 5-year intervals.

RESULTS

A total of 343 patients with Type 1 diabetes were identified. The mean follow-up period was 20.2 +/- 11.4 (mean +/- sd) years. Only 9.3% of patients were lost to follow-up. Sixty-five patients developed diabetic nephropathy. The cumulative incidence was 22.6% at 20 years and levelled off at 40.3% after approximately 35 years of diabetes duration. No significant changes in cumulative incidence were observed over time. Mean glycated haemoglobin was 8.4% in patients with proteinuria and 7.8% in a group of patients without proteinuria that was matched for age, gender and duration of diabetes (P = 0.04).

CONCLUSIONS

The cumulative incidence of diabetic nephropathy in Iceland is comparable with previously reported cumulative incidence rates and has remained unchanged. Glycaemic control was significantly better in patients without proteinuria.

The occurrence and causes of registered blindness in diabetes patients in Arhus County, Denmark

PURPOSE

To report the occurrence of registered blindness among diabetes patients in Arhus County, Denmark during 1993-2002.

METHODS

Data were obtained from a database of 7527 diabetes patients, which included all patients in the county who had been treated for or had experienced visual loss due to diabetic retinopathy since 1992. Of these, 1949 had type 1 diabetes and represented 90% of the type 1 diabetes patient population in the county, and 5459 had type 2 diabetes and represented 40% of the type 2 diabetes patient population in the county.

RESULTS

The point prevalence of legal blindness was 0.6% for type 1 and 1.5% for type 2 diabetes patients at January 1st, 2003. In type 1 diabetes patients, the major cause of blindness was proliferative diabetic retinopathy (PDR) (66.2% of all blind eyes); in type 2 diabetes patients the major causes were age-related macular degeneration (21.9%), PDR (18.0%) and diabetic maculopathy (DMac) (18.5%). During 1993-2002 there was a significant decrease in the number of blind eyes secondary to PDR (p = 0.008) in type 1 diabetes patients, and a significant increase in the number of blind eyes secondary to DMac (p = 0.005) in type 2 diabetes patients.

CONCLUSION

The major challenge in reducing diabetes-related blindness is related to the detection and treatment of an increased incidence of diabetic maculopathy in type 2 diabetes patients.

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

AIMS

Large-scale, baseline prevalence measurements in a population at the institution of systematic retinal screening are currently unavailable. We report the prevalence of all grades of retinopathy at entry into a systematic primary care-based diabetic eye screening programme.

METHODS

Primary care-based photographic screening utilizing mydriasis and three-field non-stereoscopic photography for all patients with diabetes (except those under continuing care of an ophthalmologist) in Liverpool. Sight-threatening diabetic eye disease (STED) was defined as any of: moderate preproliferative retinopathy or worse, circinate maculopathy or exudates within one disc diameter of the centre of fovea.

RESULTS

Type 1 diabetes mellitus (DM) (n = 831): baseline prevalence (95% confidence interval (CI)) of any retinopathy, proliferative diabetic retinopathy (PDR) and STED was 45.7% (42.3-49.1), 3.7% (2.4-5.0) and 16.4% (13.9-18.9), respectively. Presence of STED was associated with increased disease duration (odds ratio (OR) 1.09 per year; P < 0.0001) and higher in men (OR 2.15; P = 0.001). Type 2 DM (n = 7231): baseline prevalence (95% CI) of any retinopathy, PDR and STED was 25.3% (24.3-26.3), 0.5% (0.3-0.7) and 6.0% (5.5-6.5), respectively. Presence of STED was associated with longer time since diagnosis of DM (OR 1.03; P < 0.0001) and insulin use (OR 2.46; P < 0.0001).

CONCLUSION

This study provides baseline information for health providers on prevalence of all grades of retinopathy and STED in a large population at the establishment of systematic screening. Baseline prevalence of STED was high and highest in patients with a longer disease duration in both Type 1 and Type 2 DM.

A small number of older type 2 diabetic patients end up visually impaired despite regular photographic screening and laser treatment for diabetic retinopathy

PURPOSE

The present study describes the prevalence of visual impairment and blindness in a geographically defined population 8 years after the introduction of a screening programme in 1987 for early detection of sight-threatening diabetic retinopathy.

METHODS

Of 374 patients with diabetes, comprising 2.6% of the population in the study community, 72% were examined with fundus photography or biomicroscopy during 1994-95. These patients form the basis of this study. The screening programme was fulfilled by 93% of subjects, all of whom underwent ophthalmic examinations at least every other year. A total of 79 eyes in 52 patients received photocoagulation for macular oedema alone or in combination with severe non-proliferative or proliferative retinopathy.

RESULTS

Eight years after the implementation of the programme, only three patients, all with type 2 diabetes (diabetes diagnosed at or after 30 years of age), had visual acuity < or = 0.1. The total number of eyes with visual acuity < or = 0.5 was higher in insulin-treated type 2 diabetic patients (n = 20) than in those on oral treatment (n = 5) or diet treatment only (n = 1) (p = 0.006 in both cases). The only independent risk factor for visual impairment in eyes with sight-threatening retinopathy was age.

CONCLUSION

A small number of older type 2 diabetic patients end up with visual impairment due to unsuccessful photocoagulation of macular oedema.

Prevalence of blindness and visual impairment in a population of people with diabetes

PURPOSE

To assess the prevalence of visual impairment and the underlying causes in a population of people with diabetes.

METHOD

A population-based study of a defined population of people with diabetes in a district in the North West of England was done. There were 7652 known people with diabetes, representing 2.12% of target general population of 361050. The main outcome measures were the prevalence of blindness and significant visual impairment (less than 6/18 corrected vision in their better eye) and the underlying causes.

RESULTS

Visual acuity data on 6482 (84.7%) of the 7652 individuals were obtained. Of these, 184 had significant visual impairment (prevalence 2.84%) including 49 who were blind (vision of less than 3/60 in their better eye, prevalence 0.75%); if blindness was defined as vision less than or equal to 6/60, prevalence was 1.13% (n = 73). Details of 3 individuals could not be ascertained. Only 67 were registered, either as partially sighted (n = 42) or as blind (n = 25). In the majority (n = 133; 68%) of these 181 individuals the visual impairment was due to causes other than diabetic retinopathy.

CONCLUSIONS

The prevalence of blindness and visual impairment in our population of people with diabetes was low. Non-diabetic eye disease accounted for the majority of this visual impairment. This provides essential baseline data against which future progress can be assessed. Screening and treatment can greatly reduce the incidence of visual impairment due to diabetic retinopathy, but its impact on overall visual impairment rates in the population of people with diabetes will be more modest.

Diabetic retinopathy: are we really doing all we can for our patients?

Although it is now possible to significantly reduce the incidence of blindness secondary to diabetes mellitus, large numbers of diabetic patients still experience visual loss due to retinal complications of the disease. This implies that protocols for the diagnosis and treatment of diabetic retinopathy used in the various multicenter trials have not yet been transferred into routine clinical practice. In countries where ocular complications of diabetes have been managed on the basis of well-codified protocols for several years, the incidence of visual loss among diabetic patients has been significantly reduced. It is absolutely essential to introduce screening and treatment protocols for diabetic retinopathy promptly everywhere. Their application is within the reach of every ophthalmologist. Patients must be informed that it is important to have regular full ophthalmological examinations, before any symptoms occur; the guidelines for screening and management of retinopathy must be known and accepted by the medical community. Spreading this information among primary care physicians, ophthalmologists and diabetologists is a fundamental step in improving the health care of the diabetic patient.

Prevalence of diabetic eye disease in an inner city population: the Liverpool Diabetic Eye Study

PURPOSE

To measure the population prevalence of diabetic eye disease in an inner city setting.

METHODS

As part of a systematic screening programme all adult diabetic patients in four general practices were invited to attend for slit-lamp biomicroscopy by a retinal specialist. Data on non-attenders were available from community-based photography.

RESULTS

Of 395 diabetic patients identified, 326 attended biomicroscopy with photographic data available on a further 31, giving a 90% compliance rate. Point prevalence of diabetes in the target population was 12.4/ 1000. Demographic data included: mean age 60 years (range 13-92 years); type of control: type I 49, type II insulin-requiring (IR) 40, type II non-insulin-requiring (NIR) 268. Prevalences were as follows: any retinopathy: of all diabetic patients 33.6%, type I 36.7%, type II IR 45.0%, type II NIR 31.3%; proliferative/ advanced: all 1.1%, type I 2.0%, type II IR 0, type II NIR 1.1%; clinically significant macular oedema: all 6.4%, type I 2.3%, type II IR 16.2%, type II NIR 5.7%. The percentage of patients with retinopathy requiring follow-up by an opthalmologist was 4.5%, and 9.2% had macular exudates within 1 disc diameter of fixation or significant circinate maculopathy. Sight-threatening diabetic eye disease (STED) was found in 13.4%. A visual acuity of < or = 6/24 in the better eye occurred in 12 (3.4%) patients and of < or = 6/60 in the better eye in 3 (0.8%).

CONCLUSIONS

Compared with previous population studies, prevalences appear to have declined in type I, but remain high in type II diabetic patients and especially in those requiring insulin.

The role of digital fundus photography in diabetic retinopathy screening. Digital Diabetic Screening Group (DDSG)

PURPOSE

The role of digital monochromatic nonmydriatic fundus photography as an adjunct in the diagnosis of diabetic retinopathy is evaluated.

METHODS

197 patients were sequentially evaluated by three different techniques: dilated ophthalmoscopy by an experienced ophthalmologist, performance of 7 standard color mydriatic stereo fields, and a single digital monochromatic nonmydriatic image incorporating the disc and macula. Stereo color photographs served as the reference standard and were compared to either ophthalmoscopy performed by a physician, or a single digital photograph transmitted electronically to a reading site and evaluated by a trained non-physician grader. Sensitivity and specificity of the three methods were compared. The decision as to whether or not to refer to an ophthalmologist for potential treatment (Kaiser modified ETDRS level > 21) was then chosen for analysis.

RESULTS

A single nonmydriatic monochromatic digital photograph appeared equivalent to standard color photography and more sensitive than mydriatic ophthalmoscopy in the detection of diabetic retinopathy in this patient population. Sensitivity of digital photography compared with color photography was 78%, and the specificity 86% contrasted with comparable ratios of 34% and 100% for ophthalmoscopy versus color photography. No patient identified by ophthalmoscopy alone for referral based on retinopathy level of > 21 would have been missed by a single digital monochromatic photographic image.

CONCLUSION

A single nonmydriatic monochromatic wide field digital photograph of the disc and macula in diabetic patients is a sensitive and cost-effective means for detecting diabetic retinopathy in high-risk populations.

Impact of diabetic retinopathy screening on a British district population: case detection and blindness prevention in an evidence-based model

OBJECTIVES

To quantify case detection and blindness prevention attainable through screening for diabetic retinopathy in a district population.

DESIGN

Literature review including a pooled estimate of screening test sensitivity, and quantitative modelling, including sensitivity analyses.

SETTING AND PATIENTS

The diabetic population of a typical district health authority or health board.

MAIN RESULTS

Evidence suggests that in a British general practice based diabetic population, prevalence of retinopathy requiring treatment would be between 1% and 6%; annual incidence of blindness among diabetics with retinopathy requiring treatment would be between 6% and 9%; sensitivity of screening tests in detecting retinopathy requiring treatment would be between 50% and 88%; and treatment could prevent 77% of expected cases of blindness. Of those screened, about 4% would be correctly detected as requiring treatment during an initial screening round, but this yield could decrease to about 1% in subsequent annual screening rounds. Of those treated, about 6% would be prevented from going blind within a year of treatment and 34% within 10 years of treatment.

CONCLUSIONS

Screening and early treatment of diabetic retinopathy can prevent substantial disability. The effectiveness and efficiency of screening could be enhanced by improving the performance of current tests or increasing use of mydriatic retinal photography, and by increasing uptake, particularly among diabetics at greatest risk.

Photographic detection of retinopathy in insulin-treated diabetes. A population study in the city of Tartu, Estonia

PURPOSE

To perform a cross-sectional baseline investigation of diabetic retinopathy prevalence and metabolic control.

METHODS

Using a register of insulin-dependent diabetes mellitus in Tartu (pop. 104,791), 175 patients were invited to fundus photography; 149 (89%) participated, 99 of them diagnosed with diabetes before the age of thirty. Four Kodachrome 64 photographs per eye were taken with a Canon CR4 - 45NM camera through tropicamide-dilated pupils; slides were projected and systematically graded. Capillary blood samples (n = 132) for HbA1c determination were mailed on filter paper. Following cysteine buffer elution, Mono S ion exchange chromatography was performed (reference range 3.7 to 5.3%).

RESULTS

Any diabetic retinopathy was found in 114 patients (76.5%; 95% confidence interval, CI, 70 to 83%); mild to moderate non-proliferative retinopathy in 59 (40%; 95% CI 32 to 48%); severe non-proliferative retinopathy in 29 (19.5%; 95% CI 13 to 26%); proliferative retinopathy in 26 (17%; 95% CI 11 to 24%); 47 patients (32%) needed laser photocoagulation. Vitreous haemorrhage was observed in 9 (6%) of subjects. In patients diagnosed with diabetes before the age of 30 years, prevalence of any retinopathy was 82% (95% CI 73 to 89%) and of proliferative retinopathy 23% (95% CI 15 to 33%). Median HbA1c was 9.7% for women and 8.6% for men (95% CI for difference 0.7 to 2.1%).

CONCLUSION

Retinopathy prevalences (76-82%) are the highest reported from population-based studies. Glycaemia levels were very high and should be gradually lowered. Methods capable of validation can be successfully introduced for population-based assessment of hyperglycaemia and retinopathy prevalences.

Active prevention in diabetic eye disease. A 4-year follow-up

Ten years after the foundation of a national diabetic eye screening program in 1980, we have established a low prevalence of blindness and partial sight in type 1 and type 2 diabetics in Iceland. We ask whether the screening program is also associated with a low incidence of blindness in diabetics. We now report the results of a prospective study on the 4-year incidence of diabetic retinopathy and visual impairment in type 1 diabetics with age at onset less than 30 years. Out of 205 patients participating at baseline, 175 patients (85.4%) participated over the full 4-year period. Patients were examined annually and received laser treatment according to Diabetic- and Early Treatment Diabetic Retinopathy Study criteria. The 4-year incidence of any retinopathy was 38.1%, of proliferative retinopathy 6.6%, and of macular edema 3.4%. Out of 174 patients, 7.4% showed improvement in visual acuity of 2 Snellen lines while 2.5% experienced worsening of visual acuity of 2 Snellen lines during the 4-year period. No diabetic suffered more than 2 lines deterioration of vision and none became legally blind. The incidence of retinopathy in Icelandic type 1 diabetics participating in our annual eye screening program is low and the visual acuity stable. Our results suggest that visual impairment in diabetics can be prevented with active regular screening and standard laser therapy.

Retinal vessel dilatation and elongation precedes diabetic macular oedema

AIMS/BACKGROUND

Retinal vessel dilatation is a well known phenomenon in diabetes. In this study, the theory of whether excessive changes in diameter and length of retinal vessels occur in the development of diabetic macular oedema was tested, supporting a hypothesis that the development of diabetic macular oedema may be linked to hydrostatic pressure changes described in Starling's law.

METHODS

From fundus photographs of diabetic patients attending a regular eye screening programme, the diameter and segment length of retinal vessels were measured in three retinopathy groups (12 patients each) with diabetic macular oedema (DMO), background retinopathy and no retinopathy, over a period of approximately 4 years, ending at the time of diagnosis of diabetic macular oedema in the DMO group.

RESULTS

A statistically significant dilatation and elongation of retinal arterioles, venules, and their macular branches was found before the diagnosis of macular oedema in the DMO group. No significant changes were found in the other two groups.

CONCLUSION

It is suggested that Starling's law applies to the formation of oedema in the retina as in other tissues.

Screening for diabetic retinopathy. Initiation and frequency

A screening program for diabetic eye disease was established in Iceland in 1980. Diabetics involved in the screening program have a low prevalence of blindness, 1% in type 1 and 1.6% in type 2. We examined ways to make the screening program more efficient by identifying subgroups at low risk of developing eye disease that require treatment and therefore need less frequent screening. We studied whether diabetic eye disease screening programs may be trimmed by excluding children and examining diabetics without retinopathy biannually. Our results indicate that diabetic children under the age of 12 years do not need regular screening for eye disease. Biannual examinations seem to suffice in type 1 and 2 diabetic patients without retinopathy. However, in a setting where the eye clinic is located apart from the diabetes clinics, biannual examinations present practical problems which could result in a less effective screening for diabetic eye disease.

Screening for eye disease in type 2 diabetes mellitus

A screening program for diabetic eye disease was established in Iceland in 1980. Approximately 90% of the insulin dependent patients in Iceland undergo annual eye examination and fundus photography and about a fifth of the type 2 diabetic patients. We report on 245 diabetic patients with type 2 diabetes. Any diabetic retinopathy was present in 100 patients (41%), proliferative retinopathy had been present in 17 (7%) and 24 (10%) had clinically significant diabetic macular edema. Two-hundred and twenty-four patients (91%) had visual acuity equal or better than 6/12 in their better eye, 17 patients (7%) with 6/18-6/36 in their better eye, and 4 patients (1.6%) equal or worse than 6/60 in their better eye.

The relation between retinopathy and albumin excretion rate in insulin-dependent diabetes mellitus. From the Funen County Epidemiology of Type 1 Diabetes Complications Survey

In a population-based patient material of 138 insulin-dependent diabetics aged 25-34 years, and with a diabetes onset before 30 years of age, the relation between retinopathy and albumin excretion rate was studied. The prevalence rate of any retinopathy was 59% (81) and of proliferative retinopathy 17% (23). After 10 years' duration of diabetes, the prevalence of any retinopathy increased steeply and reached a maximum of about 90% after more than 20 years. Very few patients had proliferative retinopathy during the first 20 years, followed by a gradual increase in prevalence up to 40-50% after 25 years. Twenty-one percent (29) of the study population was found to have an increased urinary albumin excretion rate. These patients were found to have a statistically significant increase in frequency of retinopathy (p < 0.01) -and in particular of proliferative retinopathy -with increasing levels of urinary albumin excretion. Our results suggest a need for more frequent screening for diabetic retinopathy in diabetic patients with than without increased albumin excretion rate.