The 21st century has given way to a global society increasingly dependent on a variety of technologies in personal, occupational, and institutional settings [1]. The use of electronic devices in the population is massive, mobile telephony is growing in a generalized way in both developed and developing countries, with an estimated 128.9 lines / 100 inhabitants and 103.8 lines / 100 inhabitants, respectively. Regarding the possession of computers, worldwide, 49.7% have at least one computer, 78% in Europe, 65.7% in America, and 10.7% in Africa. Television continues to be the technological equipment present in a high proportion of homes [2]. In Peru, 98.4% of households have at least one information and communication technology, in 97.7% of households, there is at least one member with a cell phone. In Lima, 45.8% of households have at least one computer, 61.7% have Internet service, and access in both cases is lower in the rest of the urban and rural areas [3].

At the beginning of 2020, of the 7.75 billion total population, 67% (5.19 billion) are unique mobile phone users, 59% (4.54 billion) are Internet users, and 49% (3.8 billion) are active social media users. The average Internet user spends 6 hours and 43 minutes online every day, it varies by country, in the Philippines users spend an average of 9 hours and 45 minutes per day, compared to Japan where users spend only 4 hours and 22 minutes per day [4]. In Peru, 96% of the population with university education access the Internet, and 94.1% access the Internet through mobile phones [3].

The use of electronic devices has multiple benefits in our lives; however, they are not free from side effects and can affect health [5, 6]. Computer-digital vision syndrome (CVS), also referred to as digital eye strain, describes a group of the eye- and vision-related problems that result from prolonged computer, tablet, e-reader, and cell phone use [7].

The CVS is recognized by the International Labor Organization (ILO) within the group of occupational diseases [8]. CVS is a common problem, globally nearly 60 million people suffer from CVS; in Sri Lanka, the 1-year prevalence of CVS is 67.4% [9]. In the United States, it affects 65% of adults, and in Spain, the prevalence is 53% [10].

Among students, a high prevalence of CVS was observed, in which 95% reported at least one symptom during studying using computers [11]. In university students from Saudi Arabia, the acute and chronic presentation of CVS was 72% and 28% respectively [12].

In Peru, there are limited works on the CVS [13, 14]. On the other hand, the Covid-19 pandemic has generated a set of changes both in the work and academic context. In universities, face-to-face classes were replaced by virtual classes making use of electronic devices and therefore, greater exposure to screens, which is expected to increase the frequency of CVS. The objective of this study is to determine the frequency of computer digital vision syndrome and its associated factors in students of a private university located in the north of Lima City.

A total of 717 students of both sexes participated; eight were excluded due to incomplete data. The analysis was carried out with 709 participants with a mean age of 22.41 years (SD: 4.5; range: 16 to 60). Of the sample, 52.2% (n=370) were male, 51.1% (n=362) were between the ages of 20 and 24 years, and the majority were from the first and second academic year. Of the total participants, 48.4% (n=343) reported wearing glasses, of which 31.6% (n=224) improved a visual defect. According to gender, there was a significant difference in the use of glasses, 55.7% (n=206) in women and 40.4% (n=137) in men (p<0.001). Regarding the use of electronic devices, 39.8% (n=282) used three electronic devices, and 31.2% (n=221) two devices (Table 1).

Among the participating students, the most frequently used devices were the Smartphone and laptop, representing 96.8% (n=686) and 64.7% (n=459), respectively. Other devices such as computers, televisions, and tablets were used in a lower percentage. Regarding the exposure time, 45.6% (n=323) were exposed to some information and communication technologies (ICT) between 7 and 10 hours and 30.2% (n=214) between 4 and 6 hours. Of the students exposed to display devices, 58% (n=413) had digital computer vision syndrome. Likewise, among the most frequently reported ocular and extraocular symptoms were burning, headache, tearing, increased sensitivity to light, and itching (Table 2). Symptoms such as heavy eyelids, blurred vision, double vision, difficulty focusing for near vision, feeling that sight is worsening, and headache occurred more frequently among women (p<0.05); according to age, tearing, and excessive blinking appeared mainly between 20 and 24 years old (p<0.05).

Regarding the factors associated with computer vision syndrome. The CVS was more frequent in females, 56.9% (n=235) versus 43.1% (n=178) in males (p=0.003), it was also more frequent in the age group of 20 to 24 years (50.4%), compared to other age groups (p=0.022). Students from the accounting and financial sciences, and science and engineering faculties presented CVS in a higher percentage (p=0.005), as did the students who were in the first and second academic years (p=0.071). The participants who wore glasses presented CVS in a higher proportion, 63.4% (n=262) compared to 36.6% (n=151) who did not use glasses (p<0.001). According to the number of hours exposed to the use of ICT, CVS occurred in a higher proportion among users from 7 to 10 hours and 4 to 6 hours a day (p<0.001). Likewise, CVS also appeared in a higher percentage of students who used two and three devices (p<0.001) (Table 3).

When evaluating the type of device used, it was found that students who used a smartphone and laptop had a higher frequency of CVS. In Smartphone users, CVS was present in 95.4% (n=394) (p=0.016), and among laptop users in 69.7% (n=288) (p=0.001). The electronic devices that had the least presence of CVS were tablet, computer, and television (p=0.05) (Table 4).

Among college students exposed to electronic devices, 58% had digital computer vision syndrome. These findings are consistent with the results obtained in graduate students from a private university in Lima, where CVS was found in 61% of the students [14]. CVS is a common problem. In Saudi Arabia, 97.3% of health science students had at least one CVS symptom [16]. In computer users, the prevalence of CVS is 69.5% (95% CI: 65.6 to 73%) [17].

It is likely that the change in classes from face-to-face to virtual mode has generated an increase in the use of electronic devices and a longer exposure time to screens. Likewise, factors such as inadequate lighting, inadequate posture, and glare emitted by the screens of digital devices could have contributed to the development of CVS.

The CVS was detected mainly among women, in students belonging to the age group of 20 to 24 years, students from science-engineering and accounting financial faculties, and students who were in the first and second academic year. In the present study, the sample was predominantly made up of women and young people between 20 and 24 years of age.

On the other hand, students from the aforementioned faculties have greater exposure to these devices both in classes and in preprofessional practice. Students from other fields, such as the health sciences, find themselves in a different scenario since they participate in virtual classrooms and spend more time engaging in preprofessional practise while spending less time in front of screens. In the case of the students of the first year, they do not carry out preprofessional practices; therefore they have a greater number of virtual classes. The students who wear glasses and those who used two to three electronic devices had a higher frequency of CVS. Likewise, a higher percentage of CSV was found in students who used smartphones and laptops.

The major factors associated with CVS were either environmental (improper lighting, display position, and viewing distance) and/or dependent on the user's visual abilities (uncorrected refractive error, oculomotor disorders, and tear film abnormalities) [18]. The fact that in our study women had a higher frequency of CVS may indicate the preexistence of an eye problem, or they were the ones who most perceived ocular and extraocular symptoms. The main contributor to computer vision syndrome symptoms appears to be dry eye [19], and the prevalence of dry eye in women is higher compared to men [20].

In Saudi Arabia, CVS was reported mostly in female students and eyeglass wearers [16]. Workers who wear contact lenses and are exposed to the computer for more than 6 h a day are more likely to suffer CVS than nonlens wearers working at the computer for the same amount of time (OR = 4.85; 95% CI, 1.25-18.80; p = 0.02) [21]. Due to their easy portability, both smartphones and laptops are the devices most used by students. Advances in technology have led to the increased use of hand-held devices [18].

The CVS is a frequent entity in university students, so it requires intervention and preventive measures regarding the work environment and devices. The 20/20/20 guideline is recommended for use with electronic devices like computers and calls for 20 minutes spent in front of the screen followed by 20 seconds of fixed-point observation at a distance of 20 feet [22]. We take into consideration the study's cross-sectional design, the fact that only students from one university participated, and the fact that the results were derived from a virtual self-report as limitations. The use of glasses among students is high and appears to improve a visual defect; however, these defects were not confirmed. The use of glasses may have been to protect or alleviate symptoms caused by exposure to electronic device screens, and not necessarily to correct a visual defect. The strength of the study lies in the adequate size of the sample, whose results can approximate the real magnitude of the problem in the university population.

In university students, there is a high frequency of digital computer-digital vision syndrome, and they occur mainly in women, in students of the first year of study, and those who use two to three electronic devices. The electronic devices associated with the CVS were smartphones and laptops. Vision care prevention and promotion activities are recommended at the beginning of the academic period.