SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
VOLUME 7 NUMBER 3 • SEPTEMBER 2010
93
What’s new in diabetic retinopathy?
Linda Visser
Abstract
W
hat is new in diabetic retinopathy? In short – not
that much! Most of what we know about diabetic
retinopathy and the management of patients with
diabetic retinopathy is based on extensive research andmulti-
centre trials performed in the 1970s and 1980s, and laser
treatment remains the gold standard. Newer treatments,
such as intra-vitreal injections are mostly used as adjuncts
to laser therapy. Indications for surgery (vitrectomy) have
increased over the years as retinal imaging equipment, intra-
operative instrumentation, viewing systems and surgical
outcomes have improved.
What is abundantly clear is that theocular healthof diabetic
patients lies in the hands of the patient and his primary
physician or endocrinologist. Good control of the diabetes,
blood pressure and serum lipids as well as appropriate and
timely referral for screening for diabetic retinopathy will
go a long way to ensuring vision is maintained throughout
life. Waiting for the patient to complain of visual problems
before referring him for an eye examination could sentence
him to a life of darkness.
Background
Diabetes mellitus, a disease with significant morbidity and
premature mortality, is affecting increasing numbers of people
worldwide. In 2000, the WHO estimated there were 171 million
people with diabetes worldwide, and this has been projected to
increase to 366 million by 2030.
1
There are no national prevalence
statistics available for diabetes mellitus in South Africa, but it is
estimated that 5.5% of the population over the age of 30 years
have diabetes and 4.2% of all deaths in South Africa in 2000 were
attributable to diabetes mellitus.
2
An increase in the frequency of type 2 diabetes in the paediatric
age group has been noted in several countries and has been
associated with the increased frequency of childhood obesity.
3
These trends predict an increase in the number of individuals with
diabetes as well as associated increased costs for healthcare and the
burden of disability, especially blindness, associated with diabetes
and its complications.
Diabetic retinopathy is a leading cause of new cases of legal
blindness among working-age adults. The prevalence rate of
retinopathy for adults aged 40 years and older in the United States
is 3.4% and that for vision-threatening retinopathy is 0.75%.
4
No
equivalent statistics are available for South Africa.
Risk factors
Duration of diabetes, severity of hyperglycaemia, presence of
hypertension and raised serum lipid levels are all major risk factors
associated with the development and progression of diabetic
retinopathy.
The Wisconsin Epidemiologic Study of Diabetic Retinopathy
(WESDR) found that in type 1 diabetes, the prevalence of diabetic
retinopathy varied from 17% in persons with diabetes for less than
five years, to 97.5% in those with diabetes for 15 years or more.
Proliferative diabetic retinopathy, the most vision-threatening form
of the disease, was present in approximately 50% of type 1 patients
with 20 years’ duration of the disease.
5
In type 2 diabetes, 28.8% of persons with a known duration of
diabetes of less than five years and 77.8% of those with diabetes
for more than 15 years had retinopathy. The rate of proliferative
diabetic retinopathy varied from 2% in patients who had had
diabetes for less than five years to 15.5% of patients who had had
diabetes for 15 years or more.
6
Hyperglycaemia is the key alterable risk factor associated with the
development of diabetic retinopathy. Support for this association is
found in results of the Diabetes Control and Complications Trial
(DCCT) for type 1 diabetics and the United Kingdom Prospective
Diabetes Study (UKPDS) for type 2 diabetics.
7-9
Once retinopathy is
present, duration of diabetes appears to be a less important factor
than hyperglycaemia for progression from earlier to later stages of
retinopathy.
Intensive management of hypertension has been demonstrated
to slow progression of retinopathy.
9
Elevated serum lipid levels on
the other hand speed up the process.
10
As these factors are also
associated with substantial cardiovascular morbidity and mortality
and other complications associated with diabetes, it is reasonable
to encourage patients with diabetes to be as compliant as possible
with therapy for all medical aspects of their disease.
Natural history and clinical classification
Without intervention, diabetic retinopathy will progress from
minimal changes to more severe stages. It is important to recognise
the stages in which treatment may be most beneficial. Decades
Correspondence to: Linda Visser
Department of Ophthalmology, Nelson R Mandela School of Medicine,
University of KwaZulu-Natal, Durban
Tel: +27 (0)31 260-4341
Fax: +27 (0)31 260-4221
e-mail:
S Afr J Diabetes Vasc Dis
2010;
7
: 93–98
Linda Visser
