Public health and prevention of blindness in diabetes

Full text

EDITORIAL
Public health and prevention of blindness in
diabetes
The world is facing an epidemic of diabetes mellitus
[1].
Currently, more than 250 million people in the world have dia-
betes and it is predicted that this number will double in a little
over 20 years
[2–3]. The epidemic is not evenly distributed
around the world. While the world-wide prevalence of diabetes
is 3–4%, several countries and regions experience a prevalence
rate of diabetes of well over 10%. This includes some countries
in the Middle East, where in some cases, the prevalence of dia-
betes among middle aged adults exceed 16%
[4].
Diabetic retinopathy is a relatively new disease. Before the
discovery of insulin, less than 100 years ago, it was virtually
unknown. Diabetic retinopathy entered the medical literature
towards the middle of the twentieth century as more diabetics
survived long enough to develop the disease. In the latter part
of twentieth century, diabetic eye disease rapidly became an
important cause of blindness. Epidemiological studies have
shown that about 1/3rd of type 2 diabetics and every other
type 1 diabetic patient is likely to develop sight threatening
retinopathy within their life time. Sight threatening retinopa-
thy, i.e. diabetic macular edema and/or proliferative diabetic
retinopathy represents a significant threat to vision, and
requires medical intervention to reduce risk of the vision loss
and blindness
[5].
Blindness from diabetes soared in the latter part of the 20th
century. In Sweden, in the 1980s, it was reported that 4.4% of
type 1 and 1.4% of type 2 diabetic patients were legally blind,
with an additional 4.9% and 7.2% respectively with reduced
vision
[6]. These studies may represent a peak in blindness risk
for diabetics. This is before systematic screening and preven-
tive laser treatment was instituted in Scandinavian countries.
From Wisconsin USA, it has been also reported a 10 year inci-
dence of diabetic blindness of about 2% in type 1 and 4–5% in
type 2, with an additional 9% and 24–37% having visual
impairment [7].
Let us take as an example a hypothetical country with 2
million diabetic patients, mostly with type 2 diabetes. About
1/3rd of this group would be expected to develop sight threat-
ening retinopathy within their lifetime, and in the absence of
early diagnosis and optimal treatment, 50% of these are likely
to suffer vision loss. This worst case scenario would indicate
between 3 and 400,000 current diabetic patients having
reduced vision or blindness. If we look at the American epi-
demiology
[7], we might expect about 100,000 people to
become legally blind, and 5–700,000 to suffer from milder
visual impairment, whereas the Scandinavian statistics would
predict slightly lower rates. While the actual outcome also
depends on the overall quality of diabetes care, the availability
of ophthalmic care for those with eye symptoms and tertiary
eye care, this gives an idea of the overall scope of the problem.
Such a rate of blindness is not only a tragedy for the individ-
uals involved and a major problem for the health system,
but an economic burden on society, which needs to support
a large number of people who are unable to work because of
reduced vision.
Retinal photocoagulation has proved to be effective in
reducing the risk of vision loss and blindness, particularly in
proliferative diabetic retinopathy (DRS) and also in clinically
significant diabetic macular edema
[8]. Recently, intravitreal
VEGF antibodies have been reported to be a valuable treat-
ment modality for diabetic macular edema
[9,10]. Careful con-
trol of blood pressure, glucose and other metabolic parameters
also plays a significant role in the treatment of diabetic eye
disease.
The key to successful photocoagulation in diabetic
retinopathy is the timing of the treatment. Optimally, patients
receive retinal photocoagulation in the early stages of prolifer-
ative diabetic retinopathy or diabetic macular edema. At this
point in time, treatment is much more likely to succeed than
if the retinopathy were to be more advanced. Since patients
have no or minimal symptoms of early sight threatening
retinopathy, the only way to diagnose sight threatening
retinopathy in its early stages, and ensure the optimal timing
of treatment, is to systematically look for this disease through
screening examinations. This approach started in the 1980s,
1877-5934 Ó 2015 International Journal of Diabetes Mellitus. Published
by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.ijdm.2011.01.011
Production and hosting by Elsevier
International Journal of Diabetes Mellitus (2015) 3,1–3
Diabetes Science International
International Journal of Diabetes Mellitus
www.elsevier.com/locate/ijdm
www.sciencedirect.com

and has enjoyed enormous success [5,11,12]. Diabetic patients
were scheduled for an annual screening for retinopathy, either
through a standard eye examination with dilated pupils by an
ophthalmologist, or through fundus photography, where the
images were read by expert ophthalmologists. In both cases,
those diabetic patients who were diagnosed with sight threat-
ening retinopathy were referred to laser treatment. It was felt
at that time that annual screening examinations were adequate
for the diabetic group and experience has shown that this
approach resulted in an enormous reduction in the prevalence
of diabetic blindness [5]. Reports from the Nordic countries
now indicate the prevalence of blindness, which is considerably
lower than reported in the 1980s. Zoega reported a 0.3% blind-
ness prevalence in diabetic patients in Iceland
[13]. Olafsdottir
et al. reported about the same in a Swedish population
[14],
and Jeppesen and Bek report 0.6 and 1.5% prevalence of legal
blindness in a type 1 and 2 diabetic population in Denmark
[15]. Backlund et al. reported a one third reduction in diabetic
blindness with screening in Stockholm
[16], while Henricsson
et al. reported that the yearly incidence of new blindness was
1 per 1000 in a Swedish diabetic population in a public health
screening program
[17].
The public health approach, with regular eye screening, has
significantly reduced diabetic blindness in Nordic countries. At
the same time, diabetic eye disease remains a leading cause of
blindness in the 20–60 year age-group, and one of the most
common causes of blindness overall in many countries around
the world, including the United States
[18].
Diabetic retinopathy usually develops 5–15 years after the
onset of disease
[19]. In countries where the prevalence of dia-
betes mellitus is rising rapidly, many individuals, relatively
speaking, will have a short duration of diabetes and may not
yet have developed serious retinopathy. The rise in sight
threatening retinopathy and vision loss follows diabetes epi-
demic with a lag time of approximately 10 years. This delay
is a double edged sword. On the one hand, it may lull health
authorities into thinking that the situation is not as bad as
feared, and may thus ignore the need for a public health
approach. On the other hand, the delay provides time to set
up screening services and organize the public health approach,
the better to prevent the onslaught of sight threatening
retinopathy and to make use of the calm before the storm.
The World Health Organization and all major professional
societies in ophthalmology and diabetology recognize that reg-
ular eye screening and preventive laser treatment are essential
to prevent the diabetes epidemic from becoming an enormous
world-wide epidemic of blindness. The WHO recommends that
every diabetic patient be screened for diabetic retinopathy once
a year, and those diagnosed with sight threatening retinopathy
receive the appropriate treatment. This recommendation is
based, in part, on the experience and success of the Nordic
countries, where 30 years of experience has proved the value
of this approach. The success of retinal screening for diabetic
eye disease is proved by experience, and amply reported in
the medical literature [5,13].
Historically, diabetic eye screening started as annual screen-
ing examinations and this has proved to be adequate for the
successful prevention of blindness. However, this ‘‘one size fits
all’’ approach is clearly simplistic
[20].
Diabetic patients are at variable risk for the development of
sight threatening retinopathy. This risk is influenced by the
duration and type of diabetes mellitus, blood glucose levels,
blood pressure, the presence of retinopathy and a few other
minor risk factors
[21,22]. These risk factors create a spectrum
of risk, with some individuals at high risk and many at low
risk, including those with a short duration of diabetes mellitus.
It would clearly make more sense to adjust the screening inter-
vals to the risk profile of the individual patient, so that those at
high risk frequently come for screening examinations and
those at low risk less frequently
[23].
We have developed a mathematical algorithm, which calcu-
lates the individual risk for sight threatening retinopathy based
on duration of diabetes, hemoglobin A1C levels, blood pres-
sure and presence of retinopathy and recommends an appro-
priate screening interval for each individual
[24]. This
algorithm is available on the internet on www.risk.is and was
tested in a database of diabetic screening for 20 years in
Denmark. With this algorithm, the number of screening visits
for the population could be reduced by more than 50%, whilst
maintaining safety. This is mostly due to less frequent screen-
ing visits for diabetic patients with short duration of diabetes,
as well as those in very good medical control. This use of infor-
mation technology means that for a given amount of medical
resources, twice the number of diabetic patients may be served,
compared with fixed annual examinations. In a country with a
rising diabetes epidemic and relatively many individuals with a
short duration of diabetes, the use of information technology
may be even more important and increase the efficacy of the
public health approach even more.
A public health approach and screening for diabetic
retinopathy is a proven method to dramatically reduce the dia-
betic blindness
[25–26]. This is the only way to prevent the
world-wide diabetes epidemic from becoming an epidemic of
blindness with enormous implications for health and the econ-
omy. Information technology makes screening more effective
and feasible on a global scale.
References
[1]
Matthews DR, Matthews PC. Banting Memorial Lecture 2010^.
Type 2 diabetes as an ‘infectious’ disease: is this the Black Death
of the 21st century? Diabet Med 2011;28:2–9
.
[2]
Zimmet P, Alberti KG, Shaw J. Global and societal implications
of the diabetes epidemic. Nature 2001;414:782–7
.
[3]
Wild S, Roglic G, Green A, Sicree R, King H. Global prevalence
of diabetes: estimates for the year 2000 and projections for 2030.
Diabetes Care 2004;27:1047–53
.
[4]
Al Rubeaan Khalid. Type 2 diabetes mellitus red zone. Int J
Diabetes Mellitus 2010;1:1–2
.
[5]
Stefansson E, Bek T, Porta M, Larsen N, Kristinsson JK, Agardh
E. Screening and prevention of diabetic blindness. Acta
Ophthalmol Scand 2000;78:374–85
.
[6]
Jerneld B, Algvere P. Visual acuity in a diabetic population. Acta
Ophthalmol (Copenh) 1987;65:170–7
.
[7]
Moss SE, Klein R, Klein BE. Ten-year incidence of visual loss in a
diabetic population. Ophthalmology 1994;101:1061–70
.
[8]
Group ETDRSr: Photocoagulation for diabetic macular edema.
Early Treatment Diabetic Retinopathy Study report number 1.
Early Treatment Diabetic Retinopathy Study research group.
Arch Ophthalmol 1985;103:1796–806
.
[9]
Iacono P, Battaglia Parodi M, Bandello F. Antivascular endothe-
lial growth factor in diabetic retinopathy. Dev Ophthalmol
2010;46:39–53
.
[10]
Nicholson BP, Schachat AP. A review of clinical trials of anti-
VEGF agents for diabetic retinopathy. Graefes Arch Clin Exp
Ophthalmol 2010;248:915–30
.
2 Editorial

[11] Mayon-White VA, Jenkins LM, Knight AH. A district screening
and treatment service for diabetic retinopathy. Diabet Med
1986;3:253–6
.
[12]
Danielsen R, Helgason T, Jonasson F. Prognostic factors and
retinopathy in type 1 diabetics in Iceland. Acta Med Scand
1983;213:323–6
.
[13]
Zoega GM, Gunnarsdottir T, Bjornsdottir S, Hreietharsson AB,
Viggosson G, Stefansson E. Screening compliance and visual
outcome in diabetes. Acta Ophthalmol Scand 2005;83:687–90
.
[14]
Olafsdottir E, Andersson DK, Stefansson E. Visual acuity in a
population with regular screening for type 2 diabetes mellitus and
eye disease. Acta Ophthalmol Scand 2007;85:40–5
.
[15]
Jeppesen P, Bek T. The occurrence and causes of registered
blindness in diabetes patients in Arhus County, Denmark. Acta
Ophthalmol Scand 2004;82:526–30
.
[16]
Backlund LB, Algvere PV, Rosenqvist U. New blindness in
diabetes reduced by more than one-third in Stockholm County.
Diabet Med 1997;14:732–40
.
[17]
Henricsson M, Tyrberg M, Heijl A, Janzon L. Incidence of
blindness and visual impairment in diabetic patients participating
in an ophthalmological control and screening programme. Acta
Ophthalmol Scand 1996;74:533–8
.
[18]
Cotter SA, Varma R, Ying-Lai M, Azen SP, Klein R. Causes of
low vision and blindness in adult Latinos: the Los Angeles Latino
Eye Study. Ophthalmology 2006;113:1574–82
.
[19] Kristinsson JK. Diabetic retinopathy. Screening and prevention of
blindness [A doctoral thesis]. Acta Ophthalmol Scand Suppl;
1997. p. 1–76.
[20]
Olafsdottir E, Stefansson E. Biennial eye screening in patients
with diabetes without retinopathy: 10-year experience. Br J
Ophthalmol 2007;91:1599–601
.
[21]
Mehlsen J, Erlandsen M, Poulsen PL, Bek T. Identification of
independent risk factors for the development of diabetic retinopa-
thy requiring treatment. Acta Ophthalmol 2009
.
[22] Vesteinsdottir E, Bjornsdottir S, Hreidarsson AB, Stefansson E.
Risk of retinal neovascularization in the second eye in patients
with proliferative diabetic retinopathy. Acta Ophthalmol 2009
.
[23]
Mehlsen J, Erlandsen M, Poulsen PL, Bek T. Individualized
optimization of the screening interval for diabetic retinopathy: a
new model. Acta Ophthalmol 2010
.
[24] Stefansson E, Olafsdottir E, Gudmundsdottir A, Bek T, Mehlsen
J, Palsson O, Thorisdottir O, Einarsson S, Einarsdottir A,
Aspelund T. Information technology to control screening for
diabetic retinopathy. ARVO; 2010 [abstract #2092/A132.
www.arvo.org].
[25]
Einarsdottir AB, Stefansson E. Prevention of diabetic retinopa-
thy. Lancet 2009;373:1316–8
.
[26]
Stefansson E. Prevention of diabetic blindness. Br J Ophthalmol
2006;90:2–3
.
Einar Stefa
´
nsson
a,b,
*
Anna Bryndı
´
s Einarsdo
´
ttir
a
a
University of Iceland, Landspitali University Hospital,
Reykjavik, Iceland
b
King Saud University, Riyadh, Saudi Arabia
*
Corresponding author at: Acta Ophthalmologica,
University of Iceland, National University Hospital,
101 Reykjavı
´
k, Iceland.
Tel.: +354 543 7217 (O), +354 824 5962 (cell);
fax: +354 543 4831.
E-mail address:
einarste@landspitali.is (E. Stefa
´
nsson)
Editorial 3