**3.8 Operational definitions**

**Visual impairment:** Is any loss or abnormality in an anatomical structure or a physiological or psychological function [13]. It is presenting visual acuity of worse than either 20/40 0r 20/60 to no light perception (NLP) in either or both eyes, which includes both low vision and blindness [44].

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

**Low vision:** Even with corrective lenses, it is inability to clearly see at a distance of 6 meters (20 feet) that individuals with normal vision can clearly see at a distance of 12 meters (40 feet) or visual acuity between 6/12 and 3/60. Low vision includes mild visual impairment (VA between 6/12 and 6/18), "moderate visual impairment (VA between 6/18 and 6/60)" and "severe visual impairment (VA between 6/60 and 3/ 60)" from all causes [4].

**Blindness:** Inability to read the largest letter on a vision chart at a distance of 3 meters (10 feet) or visual acuity was worse than 3/60 [45].

**Visual acuity/VA**: Simple, noninvasive measure of the visual system's ability to discriminate two high-contrast points in space. It is usually taken at a distance of 6 m or 20 feet [9]. It is expressed in terms of A/B, where A: distance b/n observer and letters and B: expected distance that the health eye can observe.

**Obesity**: A BMI of ≥30 kg/m<sup>2</sup> is considered obese. Class 1 obesity (BMI: 30– 34.9 kg/m<sup>2</sup> ) is one of the most common subtypes. Obesity class 2 (BMI 35–39.9 kg/ m2 ), extreme obesity or morbid obesity (BMI 40 kg/m2 ) is classified as class 3 (BMI 40 kg/m<sup>2</sup> ) [46].

**Exercise:** Exercising for less than 150 minutes per 3–5 days/week is regarded poor, while exercising for more than 150 minutes per 3–5 days per week is considered good [47].

#### **3.9 Data collection procedures and tools**

We used semistructured interviewer-administered questionnaire, tape meter, and weight balance to collect data. Type of diabetes already diagnosed by physician and their ID list were used to select study participants. After obtaining consent, weight, height, and blood pressure were taken. Then they were scheduled for eye examination at the eye clinic of the same institution and had additional benefits of individualized counseling, care, and referral depending on the ocular findings. At the eye clinic, each patient had visual acuity assessment with illuminated Snellen's chart for each eye at 6 m. Training was given by principal investigator about the objective of study, data collection techniques, and ethical issues had been given to four data collectors who were BSc ophthalmic nurses and clinical nurses and one supervisor prior to actual data collection. Pre-test was applied on 17 patients in Borumeda General Hospital for evaluation of consistency, approachability, and feasibility of the questionnaire. Information obtained was strictly kept confidential.

#### *3.9.1 Ophthalmic examination*

Ophthalmic examination was performed by ophthalmic nurse and ophthalmologist. Careful ocular history, inspection, and examination of the eye using slit-lamp and dilated fundus examination were conducted. Visual acuity (using snellen chart), macular degeneration (ophthalmoscope), intraocular pressure (using tonometry), and history of night blindness for vitamin A deficiency were taken.

#### *3.9.2 Snellen chart for visual acuity test*

Visual acuity is measured by taking 6 m notation. Visual acuity was performed in a properly illuminated quiet room, using Snellen chart at 6 m to discriminate different letters. Each eye was tested separately, and the procedure was repeated, then the best average was taken. The person who could identify the letters of the size 6 at 6 m (20 at 20 feet) was said to have normal vision. The numerator expresses the distance between the observer and the letters while the denominator expresses the distance at which the letter could be distinguished by the normal eye.

#### **3.10 Data quality control**

Data quality assurance was maintained starting from design. The questionnaire was first prepared in English and then translated from English to Amharic (local language) and retranslated to Amharic by another expert to ensure understanding of the items for the participants and its consistency. Pre-test was done on 17 people living with T2DM at Borumeda Hospital. Training was given for data collectors and supervisor on the data collection tool and ethical issues during data collection.

#### **3.11 Data processing and statistical analysis**

After completing the data collection process, data were entered into Epi data-3.1 by data entry clerk, then exported into SPSS version 22 for analysis. Data completeness, consistency, and outliers were checked. Continues data were described by median and inter-quartile range while frequency with percent was used to describe the results of categorical variables. Then results were presented using tabulation, graph, and charts. Uni-variable analysis was used to describe independent variables, and bi-variable binary logistic regression analysis was performed to select potential candidate variables for the final model with cutoff point of p value ≤0.25 [48]. Model fitness was checked by Hosmer and Lemeshow goodness of fit test. Multivariable binary logistic regression analysis was done to identify significant factors of visual impairment. Adjusted odds ratio with 95% CI was computed to show significant factors. In the final model, variables with a p value ≤0.05 were considered as statistically significant.

#### **4. Ethical consideration**

The institutional review board (IRB) of the University of Gondar, College of Medicine and Health Sciences, granted ethical approval with reference number 1839/ 02/2020. Prior to data collection, Dessie Town Hospitals provided an official authorization letter. After describing the goal of the study to each participant, they signed a written informed consent form. Participants had full mandate to participate or to refuse even to withdraw at any time they want from the study. The information obtained was kept confidential.

#### **5. Dissemination plan of results**

Electronic copy of the thesis will be published by University of Gondar for online access. We also plan to disseminate the result of this study as a copy of the document to Dessie town private hospitals and Dessie Refferal Hospital. Attempts will be made to present the findings at various scientific conferences, workshops, and meetings. In addition, an effort will be made to publish the findings in a peer-reviewed scientific journal.

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

### **6. Results**

#### **6.1 Sociodemographic characteristics of participants**

Out of the total of 332 study participants, 322 have participated in the study yielding a response rate of 97%. The median age of participants was 52 years (IQR: 45–60 years) ranging from 24 to 87 years. One-hundred seventy and five (54.3%) study participants were male giving female-to-male ratio of 1: 1.18. Two hundred and twelve (65.8%) individuals were Islamic religion followers. Seventy-three (22.7%) participants were unable to read and write. One-hundred and fifteen people (35.7%) worked for a private company, 291 (90.4%) were married, and 249 (77.3%) lived in a town. The median monthly income of the participants' households was 3570 ETB (IQR: 2000–5195, Min = 800, Max = 9600ETB) (**Table 1**).


*Other\*: protestant and catholic, Private worker\*\*: construction, daily laborer, driver, mechanic, merchant, Others\*\*\*: jobless, pensioner.*

#### **Table 1.**

*Sociodemographic characteristics of people living with T2DM at Dessie town Hospitals, Northeast Ethiopia, 2020 (n = 322).*
