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Diabetic retinopathy (DR) is a complication of diabetes mellitus that can cause blindness. As the prevalence of diabetes increases globally and patients live longer, the cases of DR are increasing. To address the visual disabilities due to DR, screening of all diabetics is suggested for early detection. The rationale and principles of DR screening are discussed. Based on the available evidence, the magnitude of DR in countries in the Eastern Mediterranean region (EMR) is presented. Public health strategies to control visual disabilities due to DR are discussed. These include generating evidence for planning, implementing standard operating procedures, periodic DR screening, focusing on primary prevention of DR, strengthening DR management, health information management and retrieval systems for DR, rehabilitating DR visually disabled, using low-cost technologies, adopting a comprehensive approach by integrating DR care into the existing health systems, health promotion/counseling, and involving the community. Although adopting the public health approach for DR has been accepted as a priority by member countries of EMR, challenges in implementation remain. These include limitations in the public health approach for DR compared to that for cataract, few skilled workers, poor health systems and lack of motivation in affecting health-related lifestyle changes in diabetics.Visual disabilities due to DR are likely to increase in the coming years. An organized public health approach must be adopted and all stakeholders must work together to control severe visual disabilities due to DR.
Health screening is defined as ‘the application of a test on people who are not exhibiting symptoms and the classification of those people based on their likelihood of having a particular disease’.1 The philosophy of screening is widely used in the management of health issues to lead to a more favorable prognosis if treatment is initiated prior to severe clinical manifestation.2 This is especially true for some diseases including diabetic retinopathy (DR). DR is a potentially blinding complication of diabetes mellitus. Microvascular changes due to diabetes result in hypoxia, neovascularization and proliferative fibrovascular changes in the retina, vitreous and iris. The main stages of DR are early and severe nonproliferative (NPDR), proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME).3 An individual with NPDR may be asymptomatic and screening can help both patients and caregivers focus on primary prevention and control of risk factors. This proactive approach will result in regression of early DR changes and even delay the progression of the sight-threatening stages of DR (STDR).4,5 Applying panretinal photocoagulation (PRP) to treat STDR and a focal laser to treat the leaking vessels, in addition to the pharmacotherapy to treat DME, will delay blindness and serious morbidities such as vitreous hemorrhage and tractional retinal detachment.6,7 Thus retinal examination to determine stage of the disease could be considered a valid screening tool for early signs of DR as ‘no symptom’ due to complications of DR could be present at that time. If STDR is detected during screening, laser treatment, medications and surgeries could be offered in a timely fashion in addition to the primary prevention measures. Additionally, the cost of advanced treatment and surgeries could be reduced.
The World Health Organization (WHO) has therefore recommended that member countries should adopt the public health approach to address DR and one of the strategies is the early detection of DR.8 In the Eastern Mediterranean region (EMR) there are 23 member countries namely Afghanistan, Pakistan, Iran, Iraq, Jordan, Palestine, Syria, Lebanon, Kuwait, Qatar. Saudi Arabia, Oman, United Arab Emirates, Bahrain, Yemen, Egypt, Tunisia, Morocco, Sudan, South Sudan, Somalia, Djibouti and Libya. Depending upon the resource availability, screening for DR in diabetics could be initiated.8
DR screening needs to conform to some basic requirements to be successful.
The prevalence of preclinical stage of a disease should be high among the population to be considered ideal for screening on a large scale. The prevalence of diabetes and DR in developed and developing countries are high enough to become public health concerns.9,10 Symptoms of DR usually occur as vision starts deteriorating either due to DME or due to complications of PDR such as retinal detachment and vitreous hemorrhage.11 Thus, the absence of DR or presence of NPDR in a diabetic could be considered a preclinical stage. Based on the magnitude of DM and DR, the potential number of individuals with DR in the EMR were calculated [Table 1, Figure 1]. Population projections for the year 2010 and prevalence/ estimates in each member country were used to calculate the number of adults with diabetes.12,13 The numbers of individuals with DR were estimated based on the prevalence rates of DR as documented in different studies in the member country.14–28 In countries where data were not available, we assumed that the rate of DR was similar to a neighboring country. Thus, nearly 44347000 adults in the EMR suffer from diabetes. This magnitude justifies the need to initiate DR screening.
To justify initiation of DR screening, the results of the proposed screening test should be valid, reliable and reproducible. Validity is ability of screening to correctly categorize cases with STDR (usually symptomatic) or those without symptoms (includes ‘No DR’ and NPDR). Previous studies have validated interscreener differences for evaluating fundus photographs and assigning grades for taking action.29,30 However, simple tests such as direct and indirect ophthalmoscopy are used for DR screening in developing countries. Validity studies of these methods for DR screening are limited and more data are required using an examination by a medical retina specialist as the gold standard prior to initiating expensive interventions.
It is important that treatment of a disease that is proposed for screening should be more effective during the preclinical stage than after symptoms have developed. As DR becomes symptomatic during the advanced stages, primary prevention such as control of hyperglycemia, hypertension and hyperlipidemia can be initiated in all cases of DM with preclinical DR.31–33 Such measures prevent the onset of DR, could mitigate the effects of the early stages of NPDR and even halt the rapid progression of DR from NPDR into STDR.
The cost associated with health screening is of paramount importance for promoting such initiatives. The cost of screening should be weighed against the benefits and the cost of treatment once the condition becomes symptomatic and has progressed to an advanced stage due to late detection. Screening costs of DR depend on the type of equipment and the human resources used. In ophthalmic practice, diagnostic equipment such as direct ophthalmoscopes, indirect ophthalmoscopes, slit-lamp biomicroscopes are used to assess the posterior segment in many conditions such as DR, glaucoma, age-related macular degeneration, retinal dystrophies, retinopathy of prematurity, optic atrophy, hypertensive retinopathy, etc. Thus, an investment in strengthening eye clinics/units in undertaking comprehensive eye care will benefit screening for DR screening. Additionally the cost of DR screening will be shared among other health initiatives.
The cost of the screening also depends on who is performing DR screening. Comprehensive eye exams are best performed by ophthalmologists trained in examining the peripheral retina rather than other health staff. Nonophthalmic health personnel (Family physicians) using this equipment miss many cases of DR.34 Mydriatics at the primary health care level are often not permitted. Examination of the peripheral retina without dilation is not ideal.35 This issue can be resolved by advent of new technology. Nonmydriatic digital fundus cameras have been successfully used for DR screening at primary health care centers. The high cost of the camera is offset by the reduced screening time. Mid-level ophthalmic personnel can photograph retinal images and grade them. This will reduce the time spent by ophthalmologists in performing a detailed eye examination to document the DR changes.36 In remote areas, the digital images can be electronically transferred to a medical retina specialist at tertiary centers increasing efficiency and decreasing the cost of DR screening.37
A screening test should not pose a risk to the patient.2 Fundus examination is a noninvasive and safe procedure. Although very rare, the dilatation of the pupil (for proper evaluation of peripheral retina) could precipitate acute glaucoma in eyes with narrow angle of the anterior chamber.38 As the association between glaucoma and DR is well documented, patients with diabetes should be monitored for increased intraocular pressure 1-2 hours after a dilated fundus examination.39 In some cases, fluorescein angiography is used to locate the leaking vessels and the avascular zone of retina. Anaphylactic reactions to this dye after intravenous injection have been documented.40 If fluorescein angiography is performed in select cases, an emergency trolley and individuals trained in resuscitation should always be present.41
The screening test should impose minimum discomfort to the patients. The advent of nonmydriatic fundus camera has made DR screening fast and easy and the issues related to pharmacologic adverse event have been negated. Screening with conventional slit-lamp biomicroscopy and indirect ophthalmoscope takes less than 15 minutes. This procedure is usually performed in eye clinics while the patient is sitting or in supine position.
For type I diabetes, screening is recommended yearly after 5 years of established DM. The onset of type II diabetes is usually ambiguous hence, the patient should undergo DR screening soon after diabetes is detected and then repeated once a year.42,43 Therefore, the method of assessment and the frequency of DR screening are less likely to burden a patient with diabetes.
The success of a DR screening program will depend on having an organized quality control program, periodic evaluation of the outcomes of screening, a high-screening coverage and greater patient compliance to medical advice following screening.44 DR screening evaluation revealed that more than 75% of Asians had poor glycemic control in Malaysia and one-third of STDR cases defaulted both for periodic eye checkup and laser treatments in Oman.45,46 Thus in countries where DR screening already exists, a more aggressive approach is required. This will be possible only with a mechanism of monitoring and evaluation. In addition innovative methods should be used to improve patient compliance.
Use of digital photography in documenting DR changes has many advantages. Providing feedback to the referring physicians and patients in the form of digital images showing DR changes could reduce the noncompliance both for periodic eye screenings and following medical advice for the management of DR. If digital images of retina are captured to grade DR by health staff other than the medical retina specialist, periodic independent masked evaluation of digital images should be undertaken. Period quality checks and feedback of health personnel involved in DR screening will improve their skills.
Sustainability of a vertical health program is often questionable. Therefore, DR screening should be part of existing health programs. Diabetes control program, healthy life style initiative, health services to tackle metabolic syndromes, primary health care, community-based health initiatives, elderly health initiatives, healthy city projects, gender inequity in health care, etc. are ongoing health projects in the member countries . DR screening if integrated with these projects, will be cost effective and sustainable.
The public health approach for chronic diseases includes a number of strategies in addition to the early detection. Applying them is crucial for improving the quality of life of diabetics. The following public health strategies are recommended to improve the program approach and reduce visual disability due to DR:
Change in life style has increased the disease burden due to diabetes in many EMR countries especially those with rapidly growing economies. Proper resource allocation and providing services to the needy will depend on accurate estimates and analysis of the DR program at the national and regional levels. Estimating the magnitude of DR in the population 40 years or older along with Rapid Assessment of Avoidable Blindness has been proposed and initial studies have been performed in select countries. If this exercise is cost-effective, an important tool to plan resource allocation for DR management will be available to the program staff. Operational research to identify barriers to access and care, role of integrating telemedicine in DR screening, impact of collaboration of prevention of blindness (PBP) and diabetes control program, social barriers for the uptake of eye services and assessment of the impact of interventions (laser, medical and primary prevention) are fertile areas for further research.
Internationally acceptable strategies and Preferred Practice Patterns (PPP) should be adopted while preparing standard operating procedures for detection and management of DR at primary, secondary and tertiary levels of eye care at national and regional levels.8,14,47,48
DR could be detected in the early stages through s creening campaigns or by adopting comprehensive eye assessment of all registered diabetics. This should be complimented with the treatment oriented DR classification and training eye care staff to detect and grade digital fundus images.
Instead of focusing on eye and retina, the diabetic individual and the diabetic community as a whole should be considered. Ocular changes due to diabetes will aid health care providers in altering their approach in dealing with renal, cardiac, neurological and other systemic complications of diabetes.49,50 Periodic dialog with endocrinologists, nephrologists, cardiologists, neurologists, pharmacists and other care givers is recommended.
Family physicians, community health workers, endocrinologists and patient groups should be involved in ensuring adequate care of diabetics. Risk factors for development and progression of DR are well documented.8 Such risk factors should be adequately controlled.
Screening is not justified unless those detected through screening are offered standard interventions. Secondary level ophthalmic units should have facilities for PRP, fluorescein angiography and digital documentation. Tertiary eye unit should have an optical coherence tomography (OCT), offer laser treatment of DME, offer intravitreal injections to DR and facilities for retinal surgery. Low-vision rehabilitation and counseling should be an integral part of comprehensive eye care for diabetics at all eye units.
In spite of the best efforts, a sizable number of DR cases will have visual disabilities. These individuals should be prepared to accept rehabilitation services. Low-vision rehabilitative care should be provided within health system or linked to the existing health care systems.
In view of the poor compliance of diabetics which can be either for periodic eye checks or undergoing management of DR, proactive steps are required to identify and follow STDR cases.46
A Health information and management system (HIMS) should be established for monitoring the DR program, collecting, compiling, analyzing and disseminating data related to diabetes, DR, risk factors and management. To assess impact of the program, periodic research is required to evaluate the decline in visual disabilities due to DR, change in the quality of life of individuals with DR, the cost of service delivery and efficiency of new screening or therapeutic equipment. Based on the data from HIMS and the research findings, policy briefs should be prepared along with suggestions to improve care of DR and revise strategies through discussion with the technical committees and decision makers.
Involving mid-level eye care personnel as screeners, and counselors to improve the knowledge, attitude and health lifestyles of diabetics will be vital in the coming years. Training and developing this human resource should be incorporated into the overall strategic plan. Therefore, visual disabilities due to DR will be address in a more cost effective manner.51 General ophthalmologists should be trained in evaluating retinal pathologies and laser treatment. General ophthalmologists should be placed in different parts of the country to ensure easy accessibility for diabetics. Internationally approved training centers offer fellowship trainings for vitreo-retinal surgeries. An adequate number of specialists should be trained, provided adequate facilities and incentives to serve the needy underprivileged population.
Both screening and management of DR require resource intensive technologies which are costly. Additionally the technologies evolve rapidly. Capturing digital images of retina and transferring them from mobile units a central location for interpretation and quality control has made DR screening cost effective.52 The program should plan for maximum utilization and periodic maintenance while assessing the acquisition of equipment.
Decision makers, donors, other stakeholders, diabetes patient groups and the community should be regularly educated on DR. The involvement of stakeholders from the beginning will create a sense of ownership of the DR program. Regional and national advocacy has been initiated in some areas. They include sensitization workshops at WHO (HQ), WHO EMR and Gulf Cooperation Council (GCC) countries. The International Agency for the Prevention of Blindness IAPB EMR had also motivated the professional bodies of the member countries to improve eye care for diabetics. Towards this the theme for the ‘World Sight Day 2004’ was ‘Eye in Diabetes.’
Often vertical approaches are adopted by health professionals and organizations focusing on care for diabetes. Better collaboration of all stakeholders will improve programs aimed at DR and reduce duplication of efforts. Instead of being silent bystanders, end users should be actively involved in decision making, planning and provide feedback to the service providers.
Although DR is now a priority blinding eye disease in ‘VISION 2020’ – a global initiative to eliminate avoidable blindness - there are many challenges that countries face in adopting the public health approach to control DR.
In the first half of VISION 2020 initiative, extensive focus on cataract related blindness and prompt cure of blindness following cataract surgery have increased hopes of all stakeholders to reach the goal of reducing blindness due to cataract.53 But the same will not be true in the case of visual disabilities due to DR. In spite of providing eye care, much will depend on individuals with diabetes as they have to alter health behavior for the rest of their life. The palliative nature of DR treatment, need of frequent intervention sessions and possibility of progression of DR despite standard treatment are issues worth noting. The program staff will have the responsibility of explaining these limitations of DR program to the donors and health authorities and thus try to rationalize the expectations of the providers and the clients.
Skilled manpower (endocrinologists, medical retina specialists and vitreo-retinal surgeons) to deal with DR in EMR countries are limited. Training of general ophthalmologists and mid-level eye care personnel to screen for DR should be undertaken. Physicians and family doctors should focus on the control of the risk factors of DR. Imaging technology could be an alternative to the lack of skilled human resource in remote rural areas. However, substantial investment is required. In addition, maintaining the screening/ management equipment and communication facilities will be challenging.
A standard public health approach for DR is based on the foundation of (a) promoting healthy life style, (b) detecting and managing chronic diseases such as diabetes and hypertension and (c) care of DR in the early stages. In countries having high child and maternal mortality rates, civil unrest and poverty-related health issues, limited resources for the control of noncommunicable diseases are available. This has resulted in weak health systems to address the underlying causes of DR.54
In countries with fast growing economies, many people live a sedentary life due to the advent of automobile, entertainment facilities and the availability of nutritious food. This has resulted in high prevalence of obesity and related metabolic syndromes.55 Inertia in adopting the corrective measures by the community as well as in advocating corrective measures by health professionals have posed challenges in reducing visual disabilities due to DR.
The countries of the EMR are facing a tsunami of DR and the problem is likely to increase in the coming years. Although the DR cases have not decreased in industrialized countries, severe visual disabilities due to STDR have reduced with an organized public health approach.56,57 The aim of eliminating avoidable blindness due to diabetes in the EMR is also possible if care providers and patients work together and countries proactively apply a public health approach to DR.
Source of Support: Nil
Conflict of Interest: None declared.