A disproportionate burden of diabetic retinopathy and diabetic macular oedema exists between the adult Aboriginal and Torres Strait Islander population (respectfully referred to as Indigenous Australians hereafter) and non-Indigenous Australians. Findings from the first ever longitudinal eye disease study of these two diseases within Indigenous Australian communities are expected to guide prevention and treatment strategies, and direct improved delivery of clinical eye care.
Global increases in the prevalence of type 2 diabetes (T2D) and ever-increasing lifespans of individuals has meant that diabetic retinopathy (DR) is now a leading cause of vision impairment worldwide.1 Of importance are the two late-stage and vision-affecting complications; diabetic macular oedema (DME) and proliferative diabetic retinopathy (PDR). Improved overall systemic management of diabetes, early detection of retinopathy through available screening programs and timely interventional treatments have contributed to the reduction in blindness from PDR.2,3 As a result, over the last two decades, DME has overtaken PDR as the most common vision-affecting complication among people with T2D in high income countries. DME is an important endophenotype of DR, firstly it has been increasing in prevalence over time in parallel with increasing rates of T2D, secondly it can occur with any DR, irrespective of severity, (including PDR), and finally, its treatment is complex and expensive to deliver.4,5
DR prevention among Indigenous Australian communities remains a challenge despite knowledge of the large DR burden and significant regional, state and national investments
T2D AND DR AMONG INDIGENOUS AUSTRALIANS
In Australia, while approximately 7% of non-Indigenous adults have T2D, 30% of adult Indigenous Australians have T2D and its prevalence continues to rise.6 These inequitable rates of T2D have meant that eye complications leading to blindness have also persisted as significant public health priorities.7 Among Indigenous Australian adults with T2D, DR blindness has a prevalence of approximately 19%, has been on a precipitous rise, leads to premature, severe and irreversible vision loss in its late stages, often exists with multi-morbidity, and clinical interventions are expensive and difficult to deliver across diverse and isolated settings.8-11 DR prevention among Indigenous Australian communities remains a challenge despite knowledge of the large DR burden and significant regional, state and national investments.12
While there are existing clinical guidelines and broad-level consensus13 on the benefits of detecting DR earlier, and regular screening is known to be sight-saving and cost-effective,1 the uptake of screening across Indigenous Australian communities remains low.9,14
Current DR screening programs are often fragmented requiring:
1) delivery through specialist outreach visits for which there is a workforce shortage,
2) trained personnel to manually grade DR, and
3) expensive resources in terms of equipment, facilities and associated costs.
Community-led DR prevention initiatives that are evidence-based, and built around strong community ties and leadership, will strengthen and facilitate community stewardship, long-term sustainability and have less reliance on ‘fly-in-fly-out’ models of care. Fundamental to achieving progress on preventing DR blindness will be integrating eye health service delivery models that are culturally-capable and responsive to the multidimensional social, clinical and cultural needs of Indigenous Australians.15
MACULAR DISEASE AMONG INDIGENOUS AUSTRALIANS
Currently there is a disproportionate burden of DME that exists between Indigenous Australians and non- Indigenous Australians. The most recent national population-based estimates report approximately three times the prevalence of macular disease as a consequence of T2D (5.1 vs. 13.8%) among Indigenous people when compared to non-Indigenous people.9 Pooled prevalence analyses from major Australian studies found that while ‘any DR’ and PDR manifest at similar rates between Indigenous and non-Indigenous people, it is the prevalence of DME that is consistently reported to be higher among Indigenous Australians.7 When comparing a review of 26 studies and using the most recent DME estimates, it appears that Indigenous Australians have the fourth highest rates of DME in the world.4 Importantly, all clinical epidemiological studies that have measured DME in Indigenous people have done so using the relatively out-dated modality of retinal photography, as opposed to optical coherence tomography (OCT).7,9 Therefore, it is likely that even these rates are an underestimation.
Interestingly, the rates of age-related macular degeneration (AMD) among Indigenous Australians are lower than non-Indigenous Australians. In the National Indigenous Eye Health Survey AMD contributed to 2% of vision loss cases and in the Central Australia Ocular Health Study it was not the main cause of vision loss for any of the study participants (n=>1300).16,17 More recently, the National Eye Health Survey found that the rates among non- Indigenous Australians for intermediate AMD were 10.5%. By comparison, for Indigenous Australians, the weighted prevalence of intermediate AMD was 5.7%. For late AMD, only three cases were found among Indigenous Australians (0.17%, all cases atrophic AMD) compared to 33 cases among non-Indigenous Australians (0.96%).18
The reasons for this are not well understood, but contributing factors that are hypothesised include;
1) that Indigenous Australians are not living long enough to develop AMD,
2) individuals with higher levels of retinal pigmentation may be at a lower risk of endstage disease because of the protective effects of melanin from oxidative damage, and
3) that there are differences in environmental and genetic exposures causing AMD between Indigenous and non-Indigenous Australians.
To the best of our knowledge there is no data among Indigenous Australians for other types of maculopathies.
DR/DME RISK FACTORS
Large and cross-sectional eye health surveys including Indigenous Australians have provided estimates of the DR/ DME burden.9,14,19 Less understood are crucial social and clinical risk markers such as glycosylated haemoglobin (HbA1c), hypertension, dyslipidaemia, inflammation and socioeconomic status.5 DR epidemiology and risk profiling are critical for tailoring interventions that are specific to high-risk populations. HbA1c and blood pressure (BP) are crucial factors that have been shown to increase the risk of both the development and progression of DR in cross-sectional and prospective investigations.1,20 These basic modifiable risk factors, which are known to increase DR risk, have yet to be formally established within epidemiological studies among Indigenous Australians or used as targets for community-based intervention.9,14,19
THE DREAM PROJECT: DEFINING THE RISK AND EPIDEMIOLOGY OF ABORIGINAL MACULAR DISEASE
Thanks to the support of the Macular Disease Foundation Australia (MDFA) and its research grant scheme, the Wardliparingga Aboriginal Health Equity Theme at the South Australian Health and Medical Research Institute (SAHMRI) and the Flinders Centre for Ophthalmology, Eye and Vision Research group are embarking on a first ever longitudinal eye disease study of DR/DME among Indigenous Australian communities.
SAHMRI has built relationships and strong ties with SA Aboriginal community leaders, medical services and community organisations spanning research programs in health systems, implementation science and population health. The team has experience in Indigenous data collection and curation, and translation into how systems of care can better meet the needs of Aboriginal people. Meanwhile, Flinders University has robust academic, clinical eye health care delivery, and previous engagement with Aboriginal communities in both Central Australia and South Australia that have led to meaningful clinical eye outcomes.
The DREAM Project: Defining the Risk and Epidemiology of Aboriginal Macular Disease, commenced at the start of 2020. The proposed program of work will draw upon the existing Predicting Renal, Ophthalmic and Heart Events in the Aboriginal Community (PROPHECY) cohort as a foundation platform, which is currently recruiting Aboriginal and Torres Strait Islander people living within SA. The cohort is being established by SAHMRI’s Aboriginal Health Equity Theme to better understand many aspects of T2D and its determinants such as lifestyle, environmental, nutritional, psychological, biological and genetic factors. Based on this foundation PROPHECY platform, our group will target individuals with T2D for a second wave of assessments to describe the incidence of DR/DME and identify the factors predisposing individuals to sight-threatening disease. The DREAM Project will conduct followup eye examinations, at approximately four years post-baseline assessment, to better understand the underlying social, psychological, environmental, behavioural, clinical, biological and genomic risk factors of DR/DME among Indigenous Australians.
This initiative will further our holistic understanding of DR/DME and will allow for:
- characterisation of baseline phenotypes in individuals with and without DR/DME,
- determination of the incidence of DR/ DME and the unpacking of temporal risk factors that contribute to progression, and
- the translation of these research results into practical steps to reduce avoidable blindness.
This research agenda will address gaps in understanding broader determinants that drive DR/DME vision loss by measuring important DME risk markers and using OCT imaging. It is anticipated that the knowledge generated from this work will guide development of better prevention and treatment strategies and enable improvement in clinical management and eye health system service delivery.
If you would like to find out more, a short clip of the DREAM project is available at: www.youtube.com/ watch?v=uWoHiHcHFe8
Jose Estevez is clinician-academic (optometrist) with specialised training in Public Health. Mr Estevez dedicates his clinical and research efforts to Aboriginal eye health. While only early in his career, Mr Estevez has shown dedication and commitment to Indigenous health and is a key advocate for the health of Indigenous and priority populations across South Australia. His research has focused on overcoming inequities in eye health outcomes for Aboriginal people, with an emphasis on epidemiology and best practice of diabetic eye screenings in regional and remote areas. His work has been recognised by invitations to the advisory boards specific to Aboriginal eye health, including ethics committees. Since graduating from optometry, he became a university lecturer, is a supervisor of students in clinical placements and embarked on a PhD in 2019.
Dr Stewart Lake is an ophthalmologist who specialised in the fields of medical and surgical retina, including macular degeneration, diabetes, vitreomacular interface disorders and retinal detachment. He is also a Senior lecturer in ophthalmology at Flinders University, he consults at Flinders Medical Centre and Eyemedics, and is the lead ophthalmologist for Paediatric Retina in South Australia.
Dr Natasha Howard is the Wardliparingga Platform Lead: Implementation Science at SAHMRI. She is also an Adjunct Senior Fellow, Faculty of Health & Medical Sciences at The University of Adelaide. Her experience spans both the health and social sciences, applying population approaches to investigate how the social and built environment enables and promotes cardiometabolic health and well-being, notably for priority populations. She has been active in advocacy and mentoring of the local population health community in both research and practice.
Professor Jamie Craig is Chair and Academic Head of the Department of Ophthalmology at Flinders University and a consultant ophthalmologist specialising in glaucoma. Professor Craig is also a clinician-scientist and NHMRC Practitioner-Fellow, who translates laboratory-based research into clinical practice.
Professor Alex Brown is an Aboriginal medical doctor and researcher who grew up on the south coast of New South Wales (NSW) and trained in medicine at the University of Newcastle, before working in hospitals on the central coast of NSW then travelling overseas to complete a Master of Public Health. He has managed the local Centre for Disease Control in Alice Springs, has set up a research program in Central Australia with Baker IDI Heart and Diabetes Institute, focussing on heart disease and diabetes in Aboriginal people, and has completed his PhD on depression and heart disease in Aboriginal men. In July 2012, Professor Brown joined SAHMRI to lead Aboriginal health research. Professor Brown has since made significant contributions to national policy and research in Aboriginal health. His research focuses on overcoming disparities in health outcomes for Aboriginal people, with an emphasis on chronic disease as the primary contributor to the mortality rate differentials. Professor Brown has been instrumental in building health system responses to chronic disease, particularly in primary care.
- Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet 2010; 376(9735): 124-36.
- Zhang X, Saaddine JB, Chou CF, et al. Prevalence of diabetic retinopathy in the United States, 2005-2008. JAMA 2010; 304(6): 649-56.
- Wong TY, Mwamburi M, Klein R, et al. Rates of progression in diabetic retinopathy during different time periods: a systematic review and meta-analysis. Diabetes Care 2009; 32(12): 2307-13.
- Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. Eye Vis (Lond) 2015; 2: 17.
- Liu E, Craig JE, Burdon K. Diabetic macular oedema: clinical risk factors and emerging genetic influences. Clin Exp Optom 2017; 100(6): 569-76.
- Burke V, Zhao Y, Lee AH, et al. Predictors of type 2 diabetes and diabetes-related hospitalisation in an Australian Aboriginal cohort. Diabetes Res Clin Pract 2007; 78(3): 360-8.
- Kaidonis G, Mills RA, Landers J, Lake SR, Burdon KP, Craig JE. Review of the prevalence of diabetic retinopathy in Indigenous Australians. Clin Exp Ophthalmol 2014; 42(9): 875-82.
- Foreman J, Keel S, van Wijngaarden P, et al. Prevalence and Causes of Visual Loss Among the Indigenous Peoples of the World: A Systematic Review. JAMA Ophthalmol 2018; 136(5): 567-80.
- Keel S, Xie J, Foreman J, van Wijngaarden P, Taylor HR, Dirani M. The Prevalence of Diabetic Retinopathy in Australian Adults with Self-Reported Diabetes: The National Eye Health Survey. Ophthalmology 2017; 124(7): 977-84.
- Tapp RJ, Boudville AI, Abouzeid M, Anjou MD, Taylor HR. Impact of diabetes on eye care service needs: the National Indigenous Eye Health Survey. Clin Exp Ophthalmol 2015; 43(6): 540-3.
- Kelaher M, Ferdinand A, Taylor H. Access to eye health services among indigenous Australians: an area level analysis. BMC Ophthalmol 2012; 12: 51.
- Estevez JJ, Howard NJ, Craig JE, Brown A. Working Towards Eye Health Equity for Indigenous Australians with Diabetes. Int J Environ Res Public Health 2019; 16(24).
- Ting DS, Cheung GC, Wong TY. Diabetic retinopathy: global prevalence, major risk factors, screening practices and public health challenges: a review. Clin Exp Ophthalmol 2016; 44(4): 260-77.
- Xie J, Arnold AL, Keeffe J, et al. Prevalence of selfreported diabetes and diabetic retinopathy in indigenous Australians: the National Indigenous Eye Health Survey. Clin Exp Ophthalmol 2011; 39(6): 487-93.
- Vision 2020. Strong eyes, strong communities: A five year plan for Aboriginal and Torres Strait Islander eye health and vision 2019-2024. https://www. vision2020australia.org.au/resources/strong-eyes-strongcommunities/. Accessed June 2019.
- Taylor HR, Xie J, Fox S, Dunn RA, Arnold AL, Keeffe JE. The prevalence and causes of vision loss in Indigenous Australians: the National Indigenous Eye Health Survey. Med J Aust 2010; 192(6): 312-8.
- Landers J, Henderson T, Craig J. The prevalence and causes of visual impairment in indigenous Australians within central Australia: the Central Australian Ocular Health Study. Br J Ophthalmol 2010; 94(9): 1140-4.
- Keel S, Xie J, Foreman J, van Wijngaarden P, Taylor HR, Dirani M. Prevalence of Age-Related Macular Degeneration in Australia: The Australian National Eye Health Survey. JAMA Ophthalmol 2017; 135(11): 1242-9.
- Landers J, Henderson T, Abhary S, Craig J. Prevalence and associations of diabetic retinopathy in indigenous Australians within central Australia: the Central Australian Ocular Health Study. Clin Exp Ophthalmol 2010; 38(4): 393-7.
- Sabanayagam C, Banu R, Chee ML, et al. Incidence and progression of diabetic retinopathy: a systematic review. Lancet Diabetes Endocrinol 2019; 7(2): 140-9.