Results
According
to eligibility criteria (age ≥18y), as mentioned above, a total of 11,850 were
found eligible (Fig 3). Of them, 7567 (63.85%) took part in the investigation.
The prevalence of hyperglycemia (FBG ≥ 5.6 mmol/l) was found in 1540 (20.4%).
Of them, 1412 (91.7%) volunteered eye examination. The prevalence (with CI) of
cataract, impaired visual acuity and diabetic retinopathy was 27.8 (25.57 –
30.23), 14.1 (12.28 – 15.92) and 17.9 (15.90 – 19.90), respectively (Table 1).
Table-1: Prevalence
[% (95% CI*)] of cataract, impaired visual acuity and retinopathy (n=1412)
|
Cataract
|
n
|
% (95% CI)
|
|
a. No Cataract
|
1018
|
72.1 (69.77–74.43)
|
|
b. Cataract
|
|
|
|
Early + Mature
|
256
|
18.1 (16.1–20.1)
|
|
Hyper-mature
|
138
|
9.8 (8.25–11.25)
|
|
Total cataract
|
394
|
27.9 (25.57–30.23)
|
|
|
|
|
|
Visual
acuity
|
|
|
|
a. Normal (6/6)
|
1213
|
85.9 (84.08–87.32)
|
|
b. Impaired
|
|
|
|
Mild (6/9-6/12)
|
103
|
7.3 (5.95–8.65)
|
|
Moderate (6/18-6/36)
|
53
|
3.8 (2.8–4.8)
|
|
Severe (=>6/60)
|
43
|
3.0 (2.1–3.9)
|
|
Total impaired
|
199
|
14.1 (12.28–15.92)
|
|
Diabetic
Retinopathy
|
|
|
|
a. Absent
|
1158
|
82.0 (84.0–82.0)
|
|
b. Present
|
|
|
|
Mild (pre-proliferative
/ background)
|
170
|
12 (10.31–13.69)
|
|
Moderate to severe
(proliferative)
|
44
|
3.1 (2.20–4.00)
|
|
Maculopathy (macular
edema)
|
40
|
2.8 (1.94–3.66)
|
|
Total diabetic
retinopathy
|
254
|
17.9 (15.90–19.90)
|
CI* - confidence interval
The
prevalence of DR according to sex, social class and family history were shown
in table 2. The prevalence of DR was significantly higher among those who had
known diabetic member in their first degree relatives than those who had no
known diabetic member in their families. Regarding social class, the affluent
participants had significantly higher DR than their non-affluent counterparts.
Compared with the women the men had higher frequency though not significant.
Table-2: Prevalence [% (95% CI*)] of retinopathy
according to sex, family history (n=1412) and social class (n=1377)
|
Variables
|
n
|
% (95% CI*)
|
|
Sex
(n: men/women= 585/827)
|
|
|
|
Men
|
126
|
21.5
(17.67–24.83)
|
|
Women
|
128
|
15.5
(13.03–17.97)
|
|
Family
history of diabetes
(n: Absent/Present= 833/579)
|
|
|
|
Absent (or not known)
|
113
|
13.6
(11.29–15.91)
|
|
Present
|
141
|
24.4
(20.91–27.89)
|
|
Social
class
(n: Non affluent/affluent= 480/897)
|
|
|
|
Non affluent (poor)
|
63
|
13.1
(10.08–16.12)
|
|
Affluent
(middle and rich)
|
184
|
20.5
(17.85–23.15)
|
CI* - confidence interval
Table
3 showed the comparisons of biophysical characteristics between participants
with and without DR. The participants with DR had significantly higher age
(p<0.001), higher central obesity (WHR p<0.001; and WHtR p=0.01), higher
fasting FBG (p<0.001). Interestingly, there was no significant difference in
general obesity (BMI p=0.917). Even more interesting is that the participants
with DR had significantly lower total cholesterol (p=0.03) and lower low-density
lipoprotein (LDL p=0.047).
Table-3: Comparison of characteristics between participants with and without
retinopathy
|
|
No retinopathy
n=617
|
Retinopathy
n=145
|
|
|
Characteristics
|
Mean
|
SD†
|
Mean
|
SD
|
p‡
|
|
Age (y)
|
47.7
|
13.4
|
52.4
|
12.8
|
0.001
|
|
BMI
|
23.6
|
3.9
|
23.6
|
3.5
|
.917
|
|
WHR
|
0.896
|
0.081
|
0.925
|
0.072
|
0.001
|
|
WHTR
|
0.507
|
0.072
|
0.523
|
0.061
|
.010
|
|
SBP (mmHg)
|
127.4
|
21.9
|
129.8
|
24.2
|
.238
|
|
DBP (mmHg)
|
81.8
|
12.6
|
81.9
|
11.1
|
.921
|
|
FBG (mmol/l)
|
6.8
|
3.1
|
8.9
|
4.5
|
0.001
|
|
Chol (mg/dl)*
|
221
|
69
|
189
|
48
|
.030
|
|
TG (mg/dl)*
|
176
|
122
|
150
|
82
|
.323
|
|
HDL (mg/dl)*
|
46.2
|
10.4
|
44.5
|
11.4
|
.468
|
|
LDL (mg/dl)*
|
139.9
|
59.6
|
114.6
|
41.5
|
.047
|
† SD – standard deviation;
‡ p after unpaired t-test; * - a randomized sample size (n = 225)
The risk factors related
to DR was shown in Table 4. Compared with the non-affluent, the affluent
participants had higher risk (OR 1.54, 95% CI, 1.01 – 2.35). Likewise, the
participants from known diabetic family had greater risk (OR 1.52, CI, 1.05 –
2.20) than their counterparts having no known diabetes in their families. The
participants with diabetes had excess risk (OR 3.11, CI, 2.04 – 4.76) than
those with normal (NFG) or impaired fasting glucose (IFG). For an increasing
age, higher the quartiles greater is the risk. Similarly, higher is the central
obesity (WHR) more is the risk (Table 4); whereas, general obesity (BMI) was
found to have no effect on DR.
Discussion
This
is the first study, which addressed the prevalence of DR and visual impairment in
a coastal population. Some socio-demographic and biophysical risk factors were
also assessed. Two important aspects of the study are worth mentioning.
Firstly, the study population has least access to health care services and
diagnostic facilities. Secondly, the study areas are mostly inaccessible due to
inconvenient communication and precarious weather condition. We had some
advantages. We could refer the persons with cataract to nearby centers for
surgery organized and maintained by Fred Hollow Foundation. The local people
especially teachers and students were very much cordial. They actively and
sincerely volunteered the study in every step (carrying message to the
villagers from house to house and making list of the participants and taking
them to the investigation site.
There
are few published studies on the prevalence of visual impairment and cataract
among coastal population for comparisons. Patil S et al reported very high
prevalence of impaired visual acuity (33.0%) and cataract (82.4%) in Sindhudurg district
on the western coastal strip of India [21]. They reported high
prevalence among coastal population may be due to higher age group (>50y)
they studied.
So far
available a population based study of Bangladesh showed that overall prevalence
of DR was 5.4% among the rural people of age 30 years or older [22]. Our study
demonstrated that compared with the rural people of other areas of Bangladesh,
the coastal people had increased prevalence of DR. An estimated global
prevalence of ‘any DR’ was found 6.96% (95CI, 6.87-7.04) [23]. Thus, the global
estimate also indicates that the coastal people are more susceptible for
developing DR. A ‘Singapore Eye Study’ among the migrant Indians (age >40y)
reported that the prevalence of DR was 10.5% (95% CI, 9.3-11.8) [24]. This
finding also showed that our study population bears greater risk for DR.
With regard to risk factors, we found persons
with advancing age, higher class with family history of diabetes had excess
risk for DR. These findings are consistent with other studies [20 – 23]. In
contrast, the Singapore study [24] observed that lower income and living in
smaller houses were associated with vision threatening DR.
An interesting finding was that the level of
total cholesterol and LDL-cholesterol was found significantly lower in those
who had no DR than those who had. The findings indicate that these lipid
fractions appear to be protective against DR. The explanation is not known.
We had some limitations. The sampling technique
was a purposive one. We could not include dietary habit (salt, fruits and
vegetables), physical activities and housing status. We could not afford two
important but relevant investigations like hemoglobin A1c and
stereoscopic digital photography.
Conclusion
We conclude that the prevalence of visual
impairment and cataract is comparable with other studies; whereas, the
prevalence of DR among the coastal people was higher than that of the rural
Bangladeshis and also higher than global estimates and Indian migrants. The
persons with higher age from higher social class with higher central obesity
had excess risk for both diabetes and DR. Further study may be undertaken to
confirm the study findings and if found consistent then the coastal people need
an urgent Eye Care facilities for the prevention of visual impairment and
blindness.
Acknowledgements – We are grateful to Fred
Hollow Foundation (FHF) for their financial support. We are indebted to Prof AH
Syedur Rahman, Department of Ophthalmology, BIRDEM for his initiative to
communicate to FHF. We deeply acknowledge him posthumously with all our deepest
respect. We appreciate the cooperation extended by the Ibrahim Medical College
and the Department of Ophthalmology, BSMMU, Dhaka. We are grateful and obliged
to the teachers, students and all participants of coastal area for their
cordial and pleasant hospitality.
References
1. 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: 1047-1053.
2. World Health
Organization: Guidelines for
the prevention, management and care of diabetes mellitus. EMRO Technical publications series 32,
Geneva 2006. 
3. Khanam PA, Mahtab H, Ahmed AU, Sayeed MA, Azad
Khan AK. In
Bangladesh diabetes starts earlier now than 10 years back: a BIRDEM study. Ibrahim Med Coll J 2008; 2(1): 1-3
4. Sayeed
MA, Khanam
PA, Choudhury RI, Mahtab H, Azad Khan AK. Retinopathy and nephropathy are the
most prevalent complications among diabetic subjects in Bangladesh. Diabetologia 2005; 48(Suppl 1): Abs-944 (P: A343).
5. Khan
S, Khanam P, Latif Z, Mahtab H, Azad Khan AK, Banu A, Sayeed MA. Nephropathy was the most frequent complication among
people with diabetes after a 10-year follow up (p243, Abs). Diabetes UK, Diabetic Medicine 2006; 23[suppl-4]: 95
6. Sayeed
MA, Khanam PA, Mahtab H and Azad Khan AK. Microvascular complications among
diabetic subjects predominate in the long-term follow up: 15-year retrospective
study. Diab Res Clin Pract 2000; 50: S116.
7. Katulanda P, Priyanga Ranasinghe P and Jayawardena R. Prevalence of
retinopathy among adults with self-reported diabetes mellitus: the Sri Lanka
diabetes and Cardiovascular Study. BMC Ophthalmol 2014; 14: 100. doi: 10.1186/1471-2415-14-100
8. Sayeed
MA, Mahtab
H, Khanam PA, Latif ZA, Banu A and Azad Khan AK. Prevalence of diabetes and
impaired fasting glucose in urban population of Bangladesh. Bangladesh Med Res Counc Bull 2007; 33(1): 1-12.
9. Sayeed MA, Rhaman
MM, Fayezunnessa N, Khanam PA, Begum T, Mahtab H and Banu A. Childhood
diabetes in a Bangladeshi population.Journal of Diabetes Mellitus 2013; 3(1): 33-37.
10. Rahim MA, Hussain A, Azad Khan AK, Sayeed MA, Keramat Ali SM, Vaaler S. Rising prevalence of type 2
diabetes in rural Bangladesh: a population based study.Diabetes Res Clin Pract 2007; 77(2): 300-305.
11. Sayeed
MA, Syedur Rahman AH, Hazrat Ali M,
Subrina Afrin, Masudur Rhaman M, Mainul Hasan Chowdhury M and Banu A. Prevalence of hypertension in people living
in coastal areas of Bangladesh. Ibrahim Med Coll J 2015; 9(1):
11-17.
12. Florkowski C, Budgen C, Kendall D, Lunt H
and Moore MP. Comparison of blood glucose meters in a New Zealand
diabetes centre. Ann Clin Biochem 2009;
46: 302–305.
13. Gabir MM, Hanson RL, Dabelea
D, Imperatore G, Roumain J, Bennett PH and Knowler WC. The 1997
American Diabetes Association and 1999 World Health Organization criteria for
hyperglycemia in the diagnosis and prediction of diabetes. Diabetes Care 2000; 23(8): 1108-1112.
14. American Diabetes Association. Standards of Medical Care in Diabetes—2011. Diabetes Care 2011; 34(Suppl 1):
S11–S61.
15. Focal photocoagulation treatment of diabetic
macular edema. Relationship of treatment effect to fluorescein angiographic and
other retinal characteristics at baseline: ETDRS report no. 19. Early Treatment
Diabetic Retinopathy Study Research Group. Arch Ophthalmol 1995; 113: 1144–1155.
16. Neena J, Rachel J, Praveen V, Murthy GV.
Rapid assessment of avoidable blindness in India.PLOS One 2008; 3: e2867.
17. Prajna NV, Venkataswamy G. Cataract
blindness-The Indian Experience. Bull World Health Organ
2007; 79:259–60.
18. Klein R,
Klein BEK, Moss SE, Davis MD, Demets DL. The Wisconsin epidemiologic study of
diabetic retinopathy-X. Four year incidence and progression of diabetic
retinopathy, when age at diagnosis is 30 years or more. Arch Ophthalmol 1989; 107: 244–49.
19. Wilkinson CP, Ferris FL, 3rd, Klein
RE, et al. Proposed international
clinical diabetic retinopathy and diabetic macular edema disease severity
scales. Ophthalmology 2003; 110: 1677–82.
