DIABETIC MACULAR OEDEMA AND RELATED SIGHT LOSS AT FIRST SCREENING FOR EYE DISEASE
The Wales Diabetic Retinopathy Screening Service (WDRSS)
Darwin Minassian1, David Owens2, Angela Reidy1,3, Pritti Mehta4
Affiliations: 1 EpiVision , 2 Cardiff University, 3 London Metropolitan University, 4 UK Vision Strategy
ABSTRACT
Aims: To provide estimates for the prevalence of diabetic macular oedema (DMO) and the attributable sight loss in persons with diabetes attending a national Diabetic Retinopathy Screening Service, and the proportion that are potential candidates for referral to hospital for assessment and
treatment. Methods: Analysis of data obtained on 27,178 diabetic persons at first presentation for screening at the Diabetic Retinopathy Screening Service for Wales (WDRSS), 2004-2005. Estimation of prevalence proportions, by age and gender. Results: DMO was present in one or both
eyes of 7.05% of patients. The condition was unilateral in 4.72%, and bilateral in 2.33%. Clinically significant DMO with impaired vision attributable to DMO was present in 2.75% of patients, 0.11% being blind, and the remaining 2.64% having impaired visual acuity of <6/6 attributable to DMO.
Conclusions: The estimates pertain to the prevailing mix of Type-I and Type-II diabetes in the population, and should be of interest as inputs for epidemiological and economic models for DMO.
INTRODUCTION
The initial call of WDRSS 2004/5 for formal screening was treated as a pilot survey of the
prevalence of sight loss and of diabetic retinopathy in a diabetic population, and was prepared
for reporting at the Liverpool, UK 17th – 18th November 2005 conference and also reported
at the EASDEC 2006 conference. The rates for DMO quoted here are an expansion of the
reporting on those analyses by Minassian and Reidy (EpiVision). The work was an aspect of
the “Future Sight Loss UK” project commissioned by the RNIB / UK Vision Strategy in 2008.
Age distribution
Figure 1.
Table 2 (a) & (b). Diabetic Retinopathy (DR) and Macular Oedema (DMO)
coexistence in the same patient at first presentation for screening at the
Diabetic Retinopathy Screening Service for Wales (2004-2005)
30%
25%
a) in patients with DR &/or DMO in any eye.
20%
Diabetic
Retinopathy
(any grade)
15%
10%
DMO Absent
DMO Present
Totals
DR Absent
0.00%
3.85%
3.85%
DR Present
78.28%
17.88%
96.15%
Totals
78.28%
21.72%
100.00%
5%
METHODS
0%
12 – 19
Data were obtained on 27,178 individuals at first presentation for screening at the Diabetic
Retinopathy Screening Service for Wales (WDRSS) (2004-2005). The source of recruitment
was from a country-based register derived from General Practice registers of persons with
diabetes. Grading of diabetic retinopathy was performed on digitalised fundus images, using
the WDRSS scheme. Fundus photographs were assessed by a minimum of two trained
graders and were quality controlled against the gold standard provided by the Clinical Director
and a consulting ophthalmologist. Statistical methods included estimation of prevalence by age
and gender.
– 29
– 39
– 49
– 59
– 69
– 79
RESULTS
15.2) and 64 years respectively. About half (49%) of the patients were 65 or older (Figure1),
and 56% were male.
90 +
Table 1. Prevalence of Diabetic Macular Oedema & attributable sight loss in 27,000 persons at first
presentation for screening at the Diabetic Retinopathy Screening Service for Wales (2004-2005).
Ocular Morbidity
Demographic Features of the Sample: The mean and median age were 62.6 years (sd
– 89
% of All
Diabetic
Patients
Diabetic Macular Oedema (DMO) in one or both eyes:
Unilateral
Bilateral
7.05
4.72
2.33
Clinically Significant DMO Causing Impaired Vision 1
Clinically Significant DMO Causing Blindness 2
2.64
0.11
b) in ALL patients with diabetes.
Diabetic
Retinopathy
(any grade)
DMO Absent
DMO Present
Totals
DR Absent
67.52%
1.25%
68.77%
DR Present
25.42%
5.81%
31.23%
Totals
92.95%
7.05%
100.00%
Type of Diabetes Treatment: Seventeen percent were on insulin treatment, 53% on OHA
and the remaining 30% were managed on diet alone.
Diabetic Macular Oedema (DMO)
DMO was present in one or both eyes of 7.05% of patients. The condition was unilateral
in 4.72%, and bilateral in 2.33% (Table-1).
Clinically significant DMO with impaired vision attributable to DMO (best corrected
visual acuity <6/6 in the worst affected eye) was present in 2.75% of patients. In 0.11% of
diabetic patients the best-corrected visual acuity was ≤ 6/60 in both eyes, one or both
being attributable to DMO. This may be considered as an estimate of candidates for
referral to LVA services and for blindness or partial-sight registration. The remaining
2.64% of diabetic patients with impaired vision due to DMO but not blind may be
considered as an estimate of the pool of potential candidates for referral to hospital
services for assessment & treatment (Table-1).
Among patients with diabetic retinopathy &/or DMO, about 18% had both conditions
coexisting. In all patients with diabetes, this proportion was around 6% (Table-2)
1: Best corrected visual acuity <6/6 to >6/60 attributable to DMO, in one or both eyes of patient.
2: Best corrected visual acuity ≤ 6/60 in both eyes, one or both attributable to DMO.
DISCUSSION
The findings pertain to the mix of Type-I and Type-II diabetes prevailing in the population at the time. Our estimate of 2.64% of the ‘screened’ as potential candidates for referral to eye hospital
for assessment & treatment, is in line with the reported proportion (2.11%) of the diabetic population (Type-II) having laser treatment for DMO during the first round of screening at Tayside,
Scotland (Vallance et al, Diabetes Care 31:1126–1131, 2008). In our study, the analysis involved multi-way classification of individual eyes according to grades of retinopathy, DMO, and
levels of visual impairment attributable to DMO. The focus, however, was on classification, counts and proportions of patients, as these estimates were considered to be more useful in
construction of epidemiological and economic models for diabetic macular oedema.