This study is an educational randomized controlled trial (single blind) that was carried out on 94 patients with diabetes referred to Diabetes Clinic in Arak. Prospectively registered 5 Apr 2019, https://fa.irct.ir/trial/38401. This study adheres to CONSORT guidelines.
To determine the sample size based on similar study  a total of 42 individuals were calculated for each group, with 10% added to the sample size in each group, taking into account the rate of non-response to the questionnaires and the loss of samples during follow-up. Finally 47 individuals in each group were calculated in each group.
For sampling, a list of all patients was obtained from Diabetes Clinic of Arak. Then, 94 samples were selected by simple random sampling from patients with the criteria for entering the study and were randomly divided into two groups of control and intervention.
The conceptual framework of this study was that according to the similar study Malekmahmoodi et al.  about primary and secondary out-come and structure of intervention program based on TPB.
Inclusion criteria were patients with at least 1 year of diabetes history, no ocular complications, volunteering to participate in the study, being between 30and 70 years old, and literate at least until the fifth grade. Exclusion criteria included patients who developed ocular complications during the study at the discretion of the ophthalmologist and needed special treatment and educations, lack of patients willingness and refusing to participate in the study.
Data collection tool
The data collection instrument was a valid and reliable questionnaire that was previously used in a studies [13, 14] consisted of the following sections:
Patient Demographic Information Questionnaire including age, occupation, education, duration of the disease, and type of treatment.
Patient Awareness Questionnaire for Diabetes and Diabetic Complications, which included 10 four-choice items.
The Theory of Planned Behavior questionnaire included the following constructs:
A) Patients’ Attitudes toward Eye Care: Included 9 questions; B) Patients’ Perceived Behavior Control in Eye Care: Included 5 questions; C) Patients’ Subjective Norm for Eye Care: Included 5 questions; D) Patients’ Intention for Eye Care: Included 10 questions; and E) Patients’ performance in eye care: Included 6 questions on measuring eye care behaviors.
In this study, retinopathy prevention cares included caring behaviors regarding blood sugar control, regular visits to an ophthalmologist and timely eye examinations, adherence to a medication regimen, adherence to a proper diet, and performing appropriate physical activity. The behaviors were measured by a standard questionnaire and indices including FBS and HbA1C.
HbA1C tests were conducted using a bio-system kit and chromatography method. Bio-system kits are standard kits approved by Iran’s Ministry of Health and Medical Education.
FBS is the most common test used to diagnose diabetes. The test is done in the morning, before the person has eaten. The range of normal blood glucose is between 70 to 100 mg/dl. Levels between 100 and 126 mg/dl are considered as impaired fasting glucose or pre-diabetes. Diabetes is generally diagnosed when fasting blood glucose levels are 126 mg/dl or higher .
In this study scoring, validity and reliability of questionnaires was done based on the similar study .
In this study, based on the initial need assessment (pre-test), the educational materials were prepared and educational sessions were conducted in the form of 4 sessions as follows:
The first session focused on improving patients’ awareness of diabetes, familiarity with the structure of the eye, and proper eye care.
The second session focused on improving patients’ attitudes and subjective norms, including increasing patients’ attitudes about the importance and benefits of proper eye care and the negative consequences of not caring of it.
The third session focused on perceived behavioral control, familiarizing patients with the barriers to retinopathy and improving patients’ intentions to take proper care of their eyes.
The fourth session focused on improving retinopathy preventive behaviors, including regular blood sugar measurement, adherence to a proper diet, seeing an ophthalmologist, and taking medications regularly.
Finally 3 months after the completion of the educational intervention, using the questionnaire and FBS and HbA1C, the data of both intervention and control groups were collected again and both groups were compared with each other.
Data analysis was performed using SPSS version 22 and according to the normality of data distribution based on Kolmogorov-Smirnov test, the data were analyzed using Chi-Square, Pair t-test, and Independent t-test. Significance level of tests was considered less than 0.05.
The study protocol was reviewed and approved by the ethic committee of research in Arak university of medical sciences (Approval ID: IR.ARAKMU.REC.1397.169). This trial has been registered at Iranian Registry of Clinical Trials, IRCT20180819040834N1. Written informed consent was obtained from all participants, and data are being kept confidential and anonymous.