FREQUENCY OF RETINOPATHY AMONG DIABETICS ADMITTED IN A TEACHING
HOSPITAL OF
Huma Kayani,
Department of
Ophthalmology,
Diabetic
retinopathy is a complication of diabetes that affects the blood vessels of the
retina and leads to blindness. The
progression of retinopathy is orderly, advancing from mild abnormalities,
characterized by increased vascular permeability, to moderate and severe non-proliferative diabetic retinopathy (NPDR), characterized by the growth of new blood vessels on the
retina and posterior surface of the vitreous1.
Retinopathy is the commonest
complication of diabetes. Surveys from
developed countries show that at any time, up to 10% of people with diabetes
will have retinopathy2. The
annual incidence of retinopathy requiring ophthalmological
follow up or treatment has been reported to average 1.5% after one year3. Untreated, between 6-9% of the people with proliferative retinopathy or severe non-proliferative
disease would become blind each year.
Findings, consistent from study to study, make it possible to suggest
that, after 15 years of diabetes, approximately 2% of people become blind,
while about 10% develop severe visual handicap3.
The knowledge of the retinopathy
status of an individual is one part of the whole process of care in diabetes.
The need to screen for diabetic retinopathy is uncontroversial. Early detection of sight threatening retinopathy
and treatment by laser therapy has been shown to be effective in preventing the
onset of visual impairment.
According to National Health
Survey of Pakistan4, the prevalence of diabetes among population
aged > 25 year is 4.2%, while Shera et al5-6 have estimated a prevalence of 9.1 to
13.7%. These figures translate into 4-8
million diabetics in the country. In
spite of this high number of diabetics very little work7-8 has been
done on macrovascular and microvascular
complications of diabetes. The present
study was undertaken to estimate the frequency of retinopathy in a group of
diabetics attending a teaching hospital in
The
study was conducted between June 2001 and September 2001 at
After obtaining informed
consent, the information was obtained regarding the type, onset, duration, treatment, nature of diabetic control, associated systemic
diseases and ocular complications. Each
patient underwent a detailed ophthalmological
examination by the principal author.
After adequate mydriasis, detailed fundus
examination using indirect ophthalmosocope was
carried out to determine the presence of diabetic retinopathy and its
type. Diabetic retinopathy was
classified as non-proliferative,
when microaneurysms, haemorrhages
(dot, blot or flame shaped) or hard exudates were seen in any quadrant of
retina. Proliferative diabetic
retinopathy was diagnosed, if neovascularisation of
the retina or iris or angle, pre retinal or vitreous haemorrhage,
and or tractional retinal detachment was present. SPSS version 10 was used for data analysis.
Total
number of admissions during the study period was 4414. Out of these admissions, 540 patients were
diabetics. Three hundred and forty four
diabetics (63.7%) were female and 196 were males (36.3%). Table-1 shows the distribution of cases according
to various characteristics.
The frequency of diabetes among
admitted patients was 12.2%. The age of
the diabetics ranged between 40 and 60 years except those from Department of
Obstetrics & Gynecology, majority of whom were
less than 45 years of age. Out of these
540 diabetics, 132 had Type-1 diabetes (24.4%) while 408 had Type-2 diabetes
(75.6%). The duration of diabetes ranged
from
Among 540 diabetics, 180 had
diabetic retinopathy showing a prevalence of 33.3% (Table-2). Non-proliferative
retinopathy was present in 21.5% diabetics and proliferative
retinopathy among 11.8% diabetics. The
prevalence of retinopathy was significantly higher (P<0.001) among males
(42.8%) as compared to females (27.9%). Proliferative retinopathy was significantly higher
(P<0.01) among males (18.1%) as compared to females (8.1%). However, the difference in the prevalence of
non-proliferative retinopathy among males (24.5%) and
females (19.8%) was not significant.
The prevalence of retinopathy was
similar (33.3%) among both Type-1 as well as Type-2 diabetes. Non-proliferative
retinopathy was more common (22.5%) in Type-2 diabetes as compared to Type-1
diabetes (18.2%), whereas proliferative retinopathy
was more common in Type-1 (15.1%) as compared to Type-2 diabetes (10.8%). However, the differences were not
statistically significant (P>0.05).
Knowledge
of the retinopathy status of an individual is one part of the whole process of
care in diabetes. The implicit “gold
standard” for identifying and grading retinopathy is a retinal examination
using indirect biomicroscopy by a senior
ophthalmologist or seven field stereoscopic photographs of each eye interpreted
by experienced readers.
Several sudies9-10 have
reported the cost effectiveness of screening for retinopathy. They have established that screening for
diabetic retinopathy saves vision at a relatively low cost and this cost is
many times less than the disability payments provided to people who go blind in
the absence of a screening programme. In 1983, the annual cost of treating a
diabetic at risk of blindness was estimated to be GBP 387/- compared with
welfare benefits paid to a blind person of GBP 3575/- per annum. Similar results were reported in more recent
American and European studies11-12.
Characteristic
|
Number
|
Percent |
Sex
Male Female Total |
196 344 540 |
37.3 63.7 100.0 |
Department of Admission
Medicine Surgery Obstetrics
& Gynaecology Ophthalmology Total |
304 52 52 132 540 |
56.2 9.7 9.7 24.4 100.0 |
Type of Diabetics
Type 1 Type 2 Total |
132 408 540 |
24.4 75.6 100.0 |
Characteristic
|
Number Examined |
Positive for Retinopathy |
Frequency (%) |
Sex
Male Female Total |
196 344 540 |
84 96 180 |
42.8 27.9 33.3 |
|
Type
of Retinopathy Non
Proliferative Proliferative Total |
540 540 540 |
116 64 180 |
21.5 11.8 33.3 |
Table
3 summarizes the results of various studies on diabetic retinopathy in
developing countries. Ghana13 and
Spain14 showed a significantly lower prevalence of 22.4% and 20.9%
respectively (P<0.01). Saudi Arabia15,
Sri Lanka16 and Brazil17 reported a prevalence of 31.3%,
which is equal to our figure of 33.3%.
The prevalences reported from Egypt18
(42%) and India19 (48.1%) are significantly higher (P<0.05) from
our findings, while the prevalence notices among South African20
diabetics (40.3%) is not significantly different from the prevalence noticed in
our study (P>0.05). The reported
prevalence among 3000 diabetics from Karachi7 (26.1%) is
significantly lower than our findings.
This could be due to the younger age of that population and the shorter
duration of disease. In that study, the
duration of diabetics in 52.2% of those suffering from retinopathy was 10 years
or less, whereas in our study the duration of diabetes was 10 year or more.
Diabetic retinopathy is a
complication of both Type-1 and Type-2 diabetes mellitus.
Country
|
Author |
Year
|
No of Subjects |
Retinopathy (%) |
|
|
Ndiaye
et al13 |
1999 |
129 |
22.4 |
|
|
Lopez
et al14 |
2002 |
3544 |
20.9 |
|
|
El.
Asrar et al15 |
1998 |
502 |
31.3 |
|
|
Fernando16 |
1993 |
1003 |
31.3 |
|
Gomes
et al17 |
2002 |
50 |
31.3 |
|
|
Herman
et al18 |
1998 |
6052 |
42.0 |
|
|
Singh
et al19 |
2001 |
52 |
48.1 |
|
|
Rotchford
et al20 |
2002 |
203 |
40.3 |
|
|
Akhtar7 |
1991 |
3000 |
26.1 |
|
|
Present
Study |
2003 |
540 |
33.3 |
Prevalence is related primarily to the duration of
disease and secondarily to quality of blood sugar control. Aiello et al have shown that after 20 years,
nearly all Type-1 diabetics and greater than 60% of Type-2 diabetics will have
retinopathy regardless of diabetic control21. Vision-threatening retinopathy rarely occurs
in Type-1 patients in the first 3-5 years after diagnosis or before
puberty. Over the next 20 years, nearly
all Type-1 patients will have some degree of retinopathy. Up to 21% of Type-2 patients have retinopathy
at the time of initial diagnosis related to prolonged hyperglycemic
(“borderline”) states. The majority
(approximately > 60%) will develop retinopathy over the subsequent years21.
The Wisconsin Epidemiologic
Study of Diabetic Retinopathy (WESDR) concluded that 3.6% of those diagnosed
with Type-1 diabetes, and 1.6% of those diagnosed with Type-2 diabetes, were
legally blind. For Type-1 diabetics,
blindness was due to diabetic retinopathy in 86% of the cases. For Type-2 diabetics, blindness was related to
retinopathy in 33% of the cases; the percentage was lower due to other ocular
causes22.
The United Kingdom Prospective
Diabetic Study (UKPDS) is the longest and largest study of Type-2
patients. The study revealed that
improved control led to a reduction in retinopathy, a 25% reduction in overall microvascular complications and that one point decrease in
HbA1c was associated with 35% reduction in risk for microvascular
complications23. UKPDS has
further shown a slowed progression of retinopathy with improved control. The end result is preservation of sight,
decreased morbidity and decreased need for more expensive intervention.
Screening saves vision at a
relatively low cost, much lower than with later interventions like involving
intro-ocular surgery. The personal and societal costs are reduced with
increased productivity, decreased morbidity, and decreased disability. This is a valuable strategy to identify
patients with asymptomatic macular edema and proliferative
retinopathy. Timely intervention with laser photocoagulation, when appropriate,
can prevent visual loss.
The
secretarial assistance of Mr. Mohammad Hanif and Mr. Liaquat Ali Butt is gratefully acknowledged.
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__________________________________________________________________________________________
Dr. Huma Kayani, 9/Q Gulberg – II,
Email: naeemsaigol@hotmail.com