The study participants 18-39 years were recruited from Maseno University in Kenya from February 2019 to March 2019. Participants who had low vision were referred for low vision care. Of the 790 participants, 650 were diagnosed with CVS. Three participants were diagnosed with low vision while 137 were negative for CVS. An Informed consent was obtained from all participants and the study sought approval from Institutional Review Board of Maseno University and permission to conduct the study from National Commission for Science and Technology. The study adhered to the tenets of the Declaration of Helsinki. Each subject was given a bottle of soda and a bread to compensate for their time and accepting to participate. Participants diagnosed with refractive error were advised that they need to seek optometrist or ophthalmologist for a pair of spectacle. Other abnormalities detected were also referred for a more detailed care.
A comprehensive ocular examination was conducted among the participants. The procedures conducted include slit lamp examination, Retinoscopy, direct ophthalmoscopy and taking the visual acuity. Visual acuity was tested using a snellens chart and converted to logMAR for analysis, with a pin hole done after the presenting visual acuity taken. Slit lamp examination evaluated the anterior segment for any sign of ocular pathology. The presence of pterygium, corneal scar and lid pathologies were recorded. Retinoscopy was conducted for participants who had visual acuity score of 6/9 to 6/18 on both eye after an improvement on pin hole. After the comprehensive assessment, face to face interviews were conducted with trained interviewers where comprehensive information on computer use was recorded. Aspects on computer use such as duration of computer use were recorded. The team consisted of ten optometrists and five research assistants. The research assistants were trained thoroughly on research related issues and specifically on this topic. They were taught on what the study was all about and procedures in conducting interviews.
Assessment of clinical features of computer vision syndrome
The presence of CVS was recorded among participants who reported symptoms of eyestrain, eye fatigue, burning sensations, irritation, redness, blurred vision, and dry eyes. Reporting these symptoms with an ocular pathology such as conjunctivitis, keratitis and sub-conjunctival hemorrhage required a more comprehensive assessment before making a conclusion that it is CVS. The visual acuity of participants was assessed using snellens chart and graded as >6/12 normal, <6/12 to >6/24 mild and > 6/60 moderate. Participant’s information was recorded for the second phase of interview on computer vision syndrome. For the best corrected visual acuity, participants who required a prescription of ≥ ± 0.50 dioptric (D) were considered positive for refractive error. Participants who had normal visual acuity and no ocular pathology were grouped together during interviews on CVS.
Assessment of computer vision syndrome
Computer vision syndrome was assessed using a validated 8-item self assessment CVS questionnaire10. The participants were given a date on when the study shall be completed. On the final day they were interviewed by one of the research assistants with a structured questionnaire. The questionnaire assessed the participants on the symptoms they experienced while using computers. The questionnaires were administered seven days after the examination among the group which had visual acuity of 6/9 to 6/18 and ocular pathologies. The questionnaire had been pretested during a pilot to asses for Cronbach’s’ reliability of 0.956 and validity (assessed by performing a Pearson correlation coefficient and obtained0.000<0.05, n=78). The response rate was 99.1% and this was enhanced by maintaining a constant contact between the participants and the researcher at all time during the study period. The confounding factors included the self-reported characteristics by participants: age, gender, seating position, duration of computer use and history of ocular conditions such as low vision.
Statistical analysis was carried out using Statistical Package for Social Sciences software (SPSS; version 17.0). Logistic regression analysis was carried out to determine the associations between CVS with visual acuity, ocular pathology and refractive error and is recorded as adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Chi-square test was used to compare the visual acuity scores, ocular pathology and refractive error with CVS. All P values less than 0.05 were considered statistically significant. Linear regression analysis was performed to assess associations between CVS and presence and absence of refractive error.