Currently, the model of self reported Diabetes eye screening at Zanzibar yields only less than 10% eye patients of the persons attending the diabetic clinic, who access the eye clinic located within the same hospital premises. The reason for the low uptake of eye care services by the diabetic population may be due to lack of awareness among the diabetic community and insufficient counseling on the importance of eye screening, as it is not a mandatory part of the treatment protocol.
Our study of opportunistic eye screening at the Diabetes clinic showed a significant yield of people with diabetes (65%) having eye problems as compared to only 10% of current self reported eye screening for people with Diabetes at Zanzibar. This study found that the prevalence of DR was 28.3% (101/356) and sight-threatening diabetic retinopathy was 9% (32/356) among the study subjects. Our findings match with previous reports from Africa on DR prevalence ranging from 16 – 55% [12].
We found perfect agreement between the cataract surgeon and the ophthalmologist, as the ophthalmologist was the only Gold standard, and it indicates that if there is continuous training and upgrading of these cadres, going forward, cataract surgeons can help detect DR in the early stages, both at the tertiary diabetes clinic and at the primary health care centre level.
Introduction of mandatory eye screening for all persons attending the diabetic clinic can greatly help identify potentially blinding conditions, including DR [13]. However, identification alone will not serve the purpose, unless appropriate treatment facilities and infrastructure are created at the eye clinic. The number of patients, who had severe non-proliferative retinopathy and proliferative retinopathy, requiring laser treatment, was as high as 9% in the study group. This suggests that the hospital management should explore the possibilities of establishing a medical retina unit to provide laser treatment for those in need at this level.
Our study reports the prevalence of Visual impairment, DR among the patients attending the diabetes clinic at the tertiary centre. Our study found high prevalence of type 2 Diabetes in Zanzibar, 315 (89%) among the subjects, indicating problems in lifestyle practices and this is confirmed by the high incidence of overweight (27%) and obesity (17%) among the subjects. Our reports are higher compared to previous reports from the region, regarding the prevalence of obesity among the diabetes. It was 0.2% among males in Tanzania [14] and 21% among females in urban Cameroon [15]. This is likely to increase in the future with increasing urbanization and as lifestyles shift towards reduced exercise levels, increased stress and unhealthy foods. Interestingly, a study by Martorrel et al. noted a similar situation with South African woman, where it is culturally believed that obesity reflects health and wealth [16].
More than half of the subjects (56%) reported having a history of high blood pressure (>210/120 to 140/90 mmHg) and this indicates that there is an added risk of developing other cardiovascular diseases and a risk of getting hypertensive retinopathy [17, 18] which also needs to be managed as early as possible. At the time of recruitment for the study, the fasting blood sugar was high in 300 (84%) subjects and the presenting blood pressure was raised in 207 (56%) subjects. This high prevalence of suboptimal glycemic and blood pressure control is a cause for concern [19, 20] and reveals a lack of diabetes care at the primary care level; this report is almost similar to the previous report from South Africa [21].
Cataract was diagnosed in 178 eyes and 59 eyes had increased IOP of greater than 21 mmHg. There is published evidence that the risk of cataract increases with an increased duration of diabetes and severity of hyperglycemia [22]. There is also a strong positive association between diabetes with primary open angle glaucoma, the most common form of glaucoma or elevated intraocular pressure in the absence of optic neuropathy [23, 24].
Persons above the age of 50 years were twice at risk of developing any DR than younger persons, with an odds ratio of 2.19 with 95% Cl (1.14 -4.25). If this could have been seen and diagnosed earlier, most of these cases would have been treated. However, utilization of eye care services was poor with 61 (30%) study subjects never accessing eye care services, despite having eye problems. The barriers to accessing eye services included inadequate health education amongst diabetic patients and health care personnel. There is no diabetic screening protocol for these patients, which is vital for the early detection of DR. Instead, the eye clinic at Mnazi Mmoja Hospital depends on self-reported eye complaints, which often means that patients present late. This indicates that currently the majority of diabetic patients will progress to visual impairment, if screening and refractive services are not implemented.
Ours is the first study that assessed the prevalence of eye problems and DR among persons with diabetes in Zanzibar. Being the only tertiary and referral centre at the country, the possibility of attracting patients from all over the country was high, which was evident from the study subjects. The sample drawn for the study represented all the geographic zones in the country. Any strategic change here to improve patient care would benefit a large section of the community across the country. Moreover, this hospital is managed by the Ministry of Health, Zanzibar, with very good linkages both upwards with other tertiary centres at the Mainland, Tanzania, and downwards with all the Primary Health Care Centres, spread over the region. The primary health care units and centres can play a more active role in future by adopting an integrated approach for both diabetes and blindness prevention, through proactive screening, identification, referral and health promotion.
The main limitation of the study was that it was a hospital based study, and not a representative sample for the whole country. Although the study would help hospital policy makers to standardize the eye screening protocol for persons with diabetes attending the hospital, it will not allow us to extrapolate the information to the rest of the population.
Another limitation of this study was the DR grading done by the ophthalmologist. The method of grading was subjective, using indirect ophthalmoscope after dilation. Although the screening sensitivity of this method by an ophthalmologist showed a sensitivity of 74% in detecting DR in earlier reports [25], an objective evaluation using fundus photography would have been ideal. However, with existing resource constraints in the country, the ophthalmologist’s grading is the only possible gold standard for DR grading. Another important limitation of the study was slitlamp biomicroscopy with 78D was not done for DR grading. This would have resulted in possible underestimation of prevalence of DR. The findings from this study would help the management to expand its infrastructure for the treatment of diabetic eye diseases.
