As you study this particular topic, consider which approach to screening is most suitable for your setting at present and what needs to be planned to manage diabetic retinopathy in your setting or in Ormo, our hypothetical case study?
Screening is not intended to be a diagnostic test. Patients with positive findings must be referred for further assessment. It is therefore very important that prior to establishing any form of screening for sight-threatening diabetic retinopathy (DR), that effective treatment services are already established. There is no point in screening for a condition that cannot be treated.
Here are some key questions to consider before setting up a DR screening service in any health system:
Generally, we discuss approaches to screening as opportunistic or systematic.
Opportunistic screening relies on early detection of disease in people who present to health care providers for various complaints. It involves examining the eyes of people with diabetes when the opportunity arises e.g. when they attend a diabetes clinic for treatment or an optometrist for a general check-up.
Guidance and information for opportunistic screening need to be signposted at various levels of service delivery to raise awareness and guide persons with diabetes (often without any vision complaints) to seek an eye examination. For example, we can raise awareness about diabetic eye disease through primary health officers, fellow Optometrists, general practitioners, pharmacists and diabetologists.
Realistically, awareness-raising about eye examination for people with diabetes can only be carried out if the health system already has suitable treatment centres for referrals. For example in India, diabetes and eye screening camps set up together to reach patients in rural regions. In some of these camps, trained technicians use mobile DR screening in an equipped van with a teleconnection to the base hospital to get guidance on patients found to have retinopathy.
Systematic screening for diabetic retinopathy is organised at the population level. The basic steps are:
The first evidence of the benefits of systematic screening came from a study in the 1990s which reported that the low prevalence of blindness in people with type 1 and type 2 diabetes in Iceland was due to the systematic screening programme established in 1980. A further report showed that the prevalence of legal blindness from DR amongst people with diabetes in Iceland dropped from 2.4% in 1980 to 0.5% in 2005.
Reductions in the prevalence of blindness from diabetic retinopathy have also been reported following the introduction of systematic screening programmes in Sweden and Poland.
A systematic screening programme was introduced in England, Scotland Wales and Northern Ireland in 2002/2003 following research into the effectiveness and cost-effectiveness of systematic screening and reviews by the UK National Screening Committee and the Health Technology Board for Scotland.
In 2014, it was reported that in England and Wales, for the first time in at least five decades, diabetic retinopathy/maculopathy was no longer the leading cause of certifiable blindness among working-age adults in England and Wales.
Systematic screening can outperform opportunistic screening but it requires considerable investment. To implement systematic screening in the low- and middle-income countries where 80% of people with diabetes live will need cost-effective strategies:
Setting up some approach to screening is essential for controlling DR in every health system: either opportunistic in low prevalence, low resource settings or systematic screening in high prevalence and/or high resource settings.
Four stages of setting up DR screening
DR screening programmes develop through four stages to wit:
Stage 1: Strengthening access to effective treatment
Stage 2: Establish opportunistic screening
Stage 3: Establish systematic screening
Stage 4: Establish systematic screening with full quality assurance and
Is this four-step approach to setting up screening applicable in your setting? If it is, which step is the starting point for your health system?