**6.2 Type-2 DM and vision-related characteristics of participants**

Forty-six (14.3%) people living with T2DM had trouble in adjusting light while entering from bright to dim light. One-hundred and seventy three (53.7%) of DM patients had duration 5 years and less since diagnosis while 24 (7.5%) were new cases. Of all participants, two-hundred and sixty-four (82.0%) T2DM patients had regular follow-up in clinics. One-hundred and ninety nine (61.8%) of participants had poor or inadequate physical exercise. In 201 (62.4%) T2DM patients, the treatment option for DM was oral hypoglycemic agent without insulin. Thirty-seven (11.5%) participants were obese (BMI: median = 34.8, IQR: (23.1–27.65) and 98 (30.4%) individuals had co-morbid hypertension. Respondents had a median with IQR of baseline random plasma glucose (311, (260–396)) and fasting plasma glucose (160, (140–208)), respectively. One-hundred and eighty-seven (58.1%) participants had poor glycemic control (**Table 2**).


*OHA: oral hypoglycemic agents, Good\*: doing exercise every other day* ≥*30 min/day, Poor\*: do not doing exercise at all or doing exercise <30 min/day.*

#### **Table 2.**

*Factors related to diabetes mellitus and vision-related characteristics of participants at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*

*Visual Impairment and Its Associated Factors among People Living with Type-2 Diabetes… DOI: http://dx.doi.org/10.5772/intechopen.105793*

#### **6.3 Prevalence of visual impairment among people living with T2DM**

In the current study, the prevalence of visual impairment was 37.58% [95% CI: 32.3–42.9] with mean SEM (0.38 0.027) (**Figure 3**).

Fifty-eight (18.0%) participants with visual impairments were in the moderate visual impairment category. Among the overall prevalence of visual impairment, 43 (13.4%) had bilateral vision impairment and 78(24.2%) had monocular vision impairment out of total participants. Of all visually impaired T2DM, 107 (33.2%) and 14 (4.4%) had low vision and blindness, respectively (**Table 3**) (**Figure 3**).

Visual impairment among people living with T2DM increases with age. Among over all T2DM patients participated in this study, three (0.93%) participants aged 20– 39 years, 62 (19.25%), individuals aged 40–59 years, and 56 (17.39%) participants aged 60–87 years were visually impaired (**Figure 4**).


#### **Table 3.**

*Forms of visual impairment categories among people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020, (n = 322).*

#### **Figure 3.**

*Pie chart showing prevalence of visual impairment among people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*

#### **Figure 4.**

*Distribution of visual impairment among different age groups of people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*

In T2DM patients, visual impairment increases with duration of diabetes. Among all T2DM participants, 1 (0.31%) new T2DM cases, 42 (13.04%) participants with 5 years and below duration, and 78 (24.22%) individuals with >5 up to 24 years of duration were visually impaired (**Figure 5**).

#### **6.4 Associated factors of VI among patients living with T2DM**

Age, sex, marital status, educational level, occupation, residence, regular exercise, duration of DM, treatment option, baseline random plasma glucose, hypertension,

#### **Figure 5.**

*Magnitude of VI across duration of people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*

and glycemic control were candidates for final model. In multivariable analysis age, poor regular exercise, duration of diabetes, insulin treatment, and poor glycemic control were statistically significant with visual impairment.

The odds of having visual impairment for each age increase of a unit (a year) were 1.06 times (AOR: 1.06, 95% CI: 1.02, 1.09). Participants who relied on insulin were 14 times (AOR = 14.05, 95% CI: 2.72, 72.35) more likely to get visual impairment than those who used treatment options without insulin. The odds of having visual impairment in diabetes mellitus who had poor physical exercise were 2.91 times (AOR = 2.91,


*reference, Hosmer - Lemeshow goodness-of-fit (p = 0.781), no multicollinearity (VIF < 10).*

#### **Table 4.**

*Multivariable binary logistic regression analysis for associated factors of visual impairment among people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*

95% CI: 1.47, 5.76) more likely than those who were good in physical exercise. People living with T2DM with duration of more than 5 years were 2.42 times (AOR: 2.42, 95% CI: 1.24, 4.73) more likely to acquire visual impairment than those with duration of 5 years and lower. Those who had poor glycemic control were 2.17 times (AOR: 2.17, 95% CI: 1.13, 4.14) more likely to develop visual impairment in contrary to good glycemic control (**Table 4**).

### **7. Discussion**

Despite the wide range of effects of T2DM on vision, no thorough study has been undertaken in Ethiopia to describe visual impairment and the factors that influence it among persons with T2DM. The goal of this study was to find out how common visual impairment is among persons with T2DM and what factors contribute to it in Dessie town Hospitals in Northeast Ethiopia.

At Dessie town Hospitals, the prevalence of visual impairment among people with T2DM was 37.58% (95% CI: 32.3–42.9) in the current study. This figure is greater than the 28.9% found in a prior study at Dessie Referral Hospital [41]. This disparity is likely owing to previous researchers'study designs, which included a review of patient records as a source of data, a different study population (only newly diagnosed DM), and visual disturbance was recognized using clinical findings and questionnaire-based procedures (where visual acuity test was not applied). Furthermore, the current study's prevalence of visual impairment is higher than other studies in Nigeria (24.1%) [49], Tunisia (22.2%) [39], and Cameron (29.7%). [11] Kumasi, Ghana (18.4%) [37], Zambia (17.1%) [36], Turkey (13.5%) [33], Peru (40.2%) [31], Jordan (17.7%) [32], Hengli, Southern China (10%) [44], and Sankara Nethralaya (4.1%) [30]. This disparity is most likely related to disparities in case definition, technique used, socioeconomic status, and the quality of chronic disease care services provided. The cutoff limit for VI in this investigation was VA 6/12, whereas VA 6/18 was used in the previous trials. Those investigations, unlike the current one, used the better eye's presenting visual acuity to define visual impairment. Furthermore, their research was conducted at the community level, where there was a chance of screening normal-sighted people. However, Our study was conducted in a hospital setting, and the majority of the patients had a known diabetes problem, which could lead to an increase in the prevalence of visual impairment.

In the Nigerian study, voluntary sampling and a lower sample size were used. Purposive sampling was utilized in Tunisia, which introduced bias, and both investigations defined visual impairment using the better eye presenting visual acuity. When one eye was visually impaired but the other was not, they judged it to be no vision impairment, which understates the extent of visual impairment when compared with the current study, which takes either eye's visual acuity into account.

This study found a lower rate of unilateral vision impairment than those conducted in Yemen (76.5% [34] and South Africa (78.25%) [35]. This disparity could be attributable to changes in case definitions for vision impairment and sample sizes. In the study conducted in South Africa, study participants were T2DM aged 40, with a cutoff point of VA between 6/9.5 and 6/18, which was defined as a visual impairment, whereas in Yemen, a large sample size was used, with all conditions overestimated or the possibility of adding additional visually impaired cases.

*Visual Impairment and Its Associated Factors among People Living with Type-2 Diabetes… DOI: http://dx.doi.org/10.5772/intechopen.105793*

In the current study, visual impairment was significantly associated with advanced age, inadequate regular exercise, diabetes duration, insulin, and poor glycemic management.

For each unit (a year) increase in age, the likelihood of experiencing visual impairment increased by 1.06 times. A study in Tunisia [39], Southern China [16], and Sankara Nethralaya found comparable results [30]. Possible explanations include reduced activity, loss of muscle mass, and weight gain, which cause fatty cells to become more insulin resistant, resulting in hyperglycemia. Due to heart insufficiency, advanced age also increases the risk of macrovascular events [50].

The odds of having visual impairment in diabetes mellitus who had poor physical exercise were 2.91 times more likely than those who were good in physical exercise. This might be due to exercise that can promote an increase in the bioavailability of nitric oxide (NO), which decreases blood pressure, postexercise can increase in glycolipid uptake and utilization, which improves glucose homeostasis, insulin sensitivity and maintaining glycemic level [51–53], optimized body mass index, and modulated DNA methylation [54].

Participants with duration of diabetes of above 5 years were 2.42 times more likely to get visual impairment as compared with those with type 2 diabetes with duration of 5 years and below. This finding is in line with Zambia [36], Yemen [42], Peru [31], and China [16]. Possible reason might be long duration of diabetes has lower adherence [55], hall marker for long-term exposure to hyperglycemia [56], and potential increase risk of macrovascular and microvascular events and death [50]. Moreover, long duration linked to a reduction in insulin secretion or excessive insulin resistance in T2DM patients [24].

Diabetes mellitus patients who were managed by insulin only were 14 times more likely to have visual impairment than diabetes patients who are managed without insulin. This is consistence with study in Zambia [36], Turkey [33], Peru [31], Jordan [32]. and Sankara Nethralaya [28]. The reason is probably linked to the use of insulin alone that reflects less adherence [55] resulting in deterioration in kidney function, decline in β-cell function, or increase in insulin resistance over time [57], which in turn is associated with poor plasma glucose control and higher risk of severe diabetes.

The odds of being visually impaired were two times higher in poor glycemic control in contrary to good glycemic control, which is in line with study in Peruvians [31]. The possible reason might be poor glycemic control or persistent hyperglycemia damages retinal vasculature via activation of a pro-inflammatory mediators such as tumor necrotic factor (TNF)-2, interleukin-6, interleukin-1b, angiotensin II, endothelin-1, and vascular endothelial growth factor (VEGF) that could alter retinal blood barrier and lead to retinal vessel leakage causing macular edema and nerve scaring, which result in retinal detachment and sudden vision loss.

#### **8. Conclusion**

The prevalence of VI in Dessie town hospitals accounts for more than a third of patients living with type-2 DM implied that was a significant public health problem. Older age, poor regular exercise, duration of diabetes, insulin treatment, and poor glycemic control were statistically significant with visual impairment. Regular diabetes follow-up and visual screening for all type-2 DM should be done at older age group patients and for those having longer duration of diabetes, which can reduce visual

morbidity and vision loss. Type-2 DM patients should control glycemic level by taking medications and through adequate and regular physical exercise.

The findings of this study are essential for visual health program planners that barriers other than economic constraints are present, which prevent adoption of desired behaviors. Public health policies with educational programs and promotion of DR screening of all T2DM are needed and timely management of DR that greatly reduces the incidence of visual impairment due to diabetes. Thus integrated effort should be in place to reduce the risk of visual impairment, manage the disease progression, and prevent vision loss as a bad consequences.
