Dry eye in primary care: the relationship between digital display device usage and dry eye syndrome (DES) in medical students

Abstract

Objective

As digital display devices become more and more indispensable, associated health problems have started to increase. We aimed to investigate the frequency and relationship of digital display device usage behaviours and dry eye syndrome (DES) in medical students.

Methods

An observational, cross-sectional study was conducted on medical school students who voluntarily participated in our study online, about the duration and variety of their digital screen use, usage patterns, and protective measures, together with the Ocular Surface Disease Index (OSDI) questionnaire. Where necessary, the Schirmer-I, tear break-up time, and fluorescein staining tests were carried out.

Results

Of the 255 participants, 75.3% (n = 192) were female, 63.1% (n = 161) had no refractive vision defects, and 45.9% used smartphones for more than 5 h a day. According to the OSDI scores for DES screening, only 36.1% of the participants were normal, 17.3% had mild DES, 20.4% had moderate DES, and 26.3% had severe DES. A positive correlation was found between digital display usage time in hours per day and a high OSDI score. As the distance between the eye and the screen decreased, the DES score increased, which is significant for computer, e-book, and tablet use (P < 0.005). The DES rate of the 25 participants who underwent further evaluation was 40% for the tear break-up time test and 52% for the fluorescein staining test.

Conclusion

The high prevalence of DES due to digital screen use among medical school students highlights the importance of DES screening as a preventive measure in family medicine.

Introduction

Background

In the modern age, the use of digital display devices, which began with television and continued with computers, is present in every moment of people’s lives, both as part of their social lives and as an indispensable requirement for their professional lives given the use of tablets and smartphones. Interaction with digital display devices has increased significantly in recent years across all age groups in developed countries.¹ According to the Global Digital 2019 Report, there are 4.3 billion internet users (57% of the global population) with an average of 1 million new internet users every day. Furthermore, about 3.5 billion people (45% of the world’s population) are active social media users, and 5.1 billion people (67% of the global population) have mobile phones.² In a study conducted on the paediatric population in Europe, it was found that 68% of 3-year-old children sit in front of a computer every day,³ and 25% of 11-year-old children and 50% of 17-year-old adolescents sit in front of a digital screen every day.⁴

It has long been known that the use of digital display devices can cause some health problems, especially those related to the eyes and vision.⁵ In this context, the American Optometric Association has defined the condition resulting from the long-term use of digital display devices as digital eye strain, which is mainly related to dry eye syndrome (DES).⁶ DES is characterized by a range of ocular and vision-related symptoms and has become an important public health problem in recent years. Given the enormous increase in digital display device use, millions of people of all ages are thought to be at risk of DES.¹ Several published studies have found the prevalence of DES to be 50% or higher, which suggests that a large proportion of the population is at risk of DES and may be seeking advice and/or treatment related to this condition.

As a health problem, it is expected that DES may adversely affect people’s quality of life in terms of their physical health, psychological well-being, and levels of independence.⁷ In addition to these problems, it has become a serious economic burden. Not only are direct costs such as medical fees and drug purchases likely, but also the heavy economic burden such as declining employment rates, absenteeism, and a loss of work days as a result of the adverse impact on performance. Studies have shown that the increased financial costs caused by DES are significantly influenced by the severity and number of related hospitalizations, and therefore, early diagnosis is essential to reduce this economic burden.⁸

DES symptoms can be divided into 2 categories: those related to dry eye and those related to defective vision, accommodation, or vergence problems. The use of digital screens has also been shown to degrade blink amplitude and quality. Furthermore, when using a digital screen for reading, the screen surface is at eye level, and the palpebral fissure is wider. As a result, the larger exposed surface causes evaporation to be more and more effective.¹

In medical faculties where the use of digital screens is used as part of education, new modern educational practices have moved away from traditional coursework and increased the integration of digital and technological content in education.^9,10 The ability to quickly and easily research and access content in the virtual environment has replaced searching for source works in the library. Video content and utilities are preferred to hands-on applications, and course content read and downloaded from computer and mobile phone applications are favoured over lecture notes. This situation requires that medical students use digital devices to access instruction and information. In addition, they are exposed to digital screens for social media and entertainment purposes.

It has been found that dry eye and digital screen use have significantly increased the incidence of various health disorders, stress, and migraine headaches among university students.¹¹ In a study on health science students, including medical students, it was reported that different eye symptoms were common among the students who were using different electronic devices.¹² Another study investigating DES in medical students found that higher levels of psychological stress were associated with a higher risk of dry eye.¹³ Considering all these studies, it seems that there is a need to investigate health problems such as DES caused by digital devices, especially among medical students.

Objective

Family practice is the primary healthcare provider that helps citizens access healthcare services and physicians. The most important task of family physicians is to provide preventive health services and to conduct health examinations. In this context, the need exists to investigate the feasibility of primary care screening for the early detection and prevention of eye disease associated with the use of digital screens such as DES. For this purpose, we aimed to investigate the frequency and relationship of digital display device usage behaviours and DES prevalence among medical students.

Methods

Study design

This was a cross-sectional and descriptive study.

Setting

The study was carried out at a family medicine practice at a medical school in Erzurum in eastern Turkey.

Ethical approval

Ethics committee approval was obtained from the Ataturk University Faculty of Medicine Clinical Research ethics committee (approval number: 27/06/2019/05-03).

Study size

The GPower 3.1.9.4 software program was used to calculate the sample size of the study. In this program, effect size values such as “small,” “medium,” and “large” were predefined by the program in line with Cohen’s recommendations.¹⁴ Since it was thought that it would be more difficult to reach students and that the participation rate would be low during the COVID-19 pandemic, a medium effect size (q = 0.3) was determined to calculate the sample size. Following the power analysis using GPower, the number of participants required for the study was found to be 282, with a type 1 error of 0.05, a confidence interval of 80%, and a medium effect size.

Participants

Our study included medical students from Ataturk University Faculty of Medicine who participated voluntarily and provided their informed consent. Although the initial plan was to reach out to students in person, due to the SARS-CoV-2 pandemic, a decision was taken to instead contact them online as part of the measures to prevent the transmission and spread of the virus. In the online questionnaire, individuals were asked whether they wanted to participate in the study. Those who answered “no” were excluded from the study. A total of 192 students, namely, those who were younger than 18 years (n = 3), were over 25 years of age (n = 10), were smokers (n = 74), were using topical medication in the eye (n = 3), had a chronic systemic disease (n = 13), provided incomplete data (n = 1), wore contact lenses (n = 38), had a known eye disease (n = 45), had a history of ocular trauma (n = 2), or had a history of ocular surgery (n = 3), were excluded from the study. The 255 remaining students were included in the study (Table 1).

Questionnaire

The study questionnaire form was created on Google Forms, which is an online survey platform. The survey was administered anonymously by sending the link to the survey to the faculty students through the School of Medicine’s institutional communication resources.

The participants were asked to complete the online questionnaire, which comprised questions regarding their patterns of digital screen use and the Turkish translation of the Ocular Surface Disease Index (OSDI) questionnaire online (Table 2). Three different clinical diagnostic methods (Schirmer-I test, fluorescein staining test, and the tear break-up time test [TBUT]) were applied to the 25 participants who met the conditions established by the OSDI questionnaire, and the results were evaluated (Table 1).

There is no clinically accepted and standardized questionnaire regarding the use of digital display devices. In the questionnaire we designed, the participants were asked questions about their demographic characteristics, such as their age, gender, and eye health status; protective measures taken when using digital screens, such as the duration of their digital screen use, variety, and usage style; and awareness of DES (Table 3). Each question in the OSDI questionnaire, which consists of 3 main sections (i.e. eye symptoms, visual function, and environmental factors), is scored from 0 to 4. In line with the original questionnaire, we determined the OSDI score by multiplying the sum of the scores for the 12 questions by 25 and dividing that total by the number of questions answered.¹⁵

According to the OSDI scoring, 0–12 points are considered normal, 13–22 points indicate mild ocular surface disease, 23–32 points infer moderate ocular surface disease, and 33–100 points denote severe ocular surface disease. For the standardized diagnosis of DES, according to the diagnostic algorithm of the TFOS DEWS II workshop report, the TBUT for advanced research and the ocular surface staining test with Schirmer-I and fluorescein were performed for the participants who had clinical suspicion of ocular surface disease based on the OSDI questionnaire because the OSDI offers a reliable way of identifying patients with severe disease.¹⁶

The Schirmer-I test was determined by measuring the wetness in mm of the filter paper 5 min after placing calibrated filter strips on the outer third of the participants’ lower eyelids under local anaesthesia (0.5% proparacaine hydrochloride; Alcain, Alcon). Values less than 6 mm were considered abnormal.¹⁷ The TBUT test was measured in seconds as the time for the first dry spot to appear in the corneal epithelium after blinking under the cobalt blue light of a biomicroscope by dropping fluorescein dye onto the ocular surface, and <10 s or less was considered abnormal.¹⁸ The fluorescein staining results were simultaneously evaluated according to the Oxford Grading Scale.¹⁹

Statistical analysis

The SPSS 20 program (IBM, NY) was used for the statistical analyses. In terms of the descriptive statistics, frequency and percentage were used to present the categorical data and the mean and standard deviation for the numerical data. The suitability of the numerical variables to the normal distribution was examined using the Kolmogorov–Smirnov test. One-way ANOVA was used for the normally distributed variables, and the Kruskal–Wallis test was applied for the non-normally distributed variables. Post hoc analysis was performed in the cases where statistically significant differences were detected. In this context, the Bonferroni test was used if the variances were equal, and Dunnett’s T3 test was used if they were not. In the analysis of the categorical data, Pearson’s chi-square test was used when less than 20% of cells have expected frequencies lower than 5, and Fisher’s exact test was used when it was greater than 20%. P < 0.05 was accepted as the statistical significance limit.

Results

Descriptive data

The total number of students in the medical faculty at the time of the study was 1,615. Of these, only 505 students could be reached, and their online survey responses were recorded. Fifty-eight students voluntarily refused to answer the questionnaire, and the students with known eye diseases were excluded under the exclusion criteria. As a result, only 255 eligible participants were enrolled, and the inclusion rate was 50.5%.

Of the 255 participants who fully met the inclusion criteria and whose responses were analysed, 75.3% (n = 192) were female, and 24.7% (n = 63) were male. The mean age of the participants was 20.0 ± 1.7 years. While 63.1% (n = 161) of the participants had no refractive errors, 17.6% (n = 45) were myopic, and 1.6% (n = 4) were hypermetropic. Among the participants, 72.9% (n = 186) did not wear glasses at any time during the day. While all the participants in the study used smartphones, the digital display device with the lowest usage rate was the game console. Just under half (45.9%) of the participants used a smartphone for more than 5 h per day, and 22.4% used a computer for more than 5 h per day. In general, the preference rates for protective filters were quite low, and most filters were used on mobile phones (31.4%). A medium distance between 30 and 50 cm was preferred when using digital display devices. Furthermore, low screen brightness was more preferred when using mobile phones, while other digital display devices were used with medium screen brightness (Table 4).

The percentage of participants who reported using a digital display device for educational purposes in any area of the medical school was 91.4% (n = 233). The views of the participants about the effects of digital screens on health are presented in Table 2. The participants were generally aware of the various effects of using digital display devices on health.

Main results

According to the OSDI scale questions used in the study and the participants’ responses, 31% of the participants experienced light sensitivity all the time or most often in the last week, 21.9% had pain or tingling in their eyes, and 21.6% had blurred vision.

The mean value of the participants’ OSDI scores was 25.5 ± 23.0. The men’s mean OSDI score was 20.9 ± 22.4, and the mean score of the female participants was 27.0 ± 23.1. While there was a statistically significant difference between the participants’ OSDI scores according to gender (P = 0.026), there was no statistically significant relationship between the participants’ OSDI scores and their ages (P = 0.218). The relationship between the participants’ refractive errors and OSDI scores is presented in Table 5. As shown in Table 5, a statistically significant difference was found between the OSDI scores of the participants (P = 0.008). No statistically significant difference was apparent between the OSDI scores based on whether the participants wore permanent glasses or not (P = 0.066).

The participants who never used digital devices had lower OSDI scores than those who used devices with a digital display. In the post hoc analysis, a significant difference was determined in the OSDI scores between those who used their smartphones for less than 1 h per day and those who used them for 1–5 h. Significant differences were also found for the OSDI scores between the e-book users who used these devices for less than an hour and those who did not use them at all. Similarly, significant differences were noted between those who used tablets for 1–5 h and those who did not use them at all, between those who used an LED TV for more than 5 h a day and those who did not use one at all, and between the use of protective filters and OSDI scores. The latter was evident from a comparison of the OSDI scores as a function of whether the participants used protective filters when using computers, e-books, and LED TVs. At the same time, a significant relationship was found between the distance between the eye and the screen and the OSDI score when using computers, tablets, and e-books. In the post hoc analysis, there was a significant difference between those who used a computer at a distance of less than 30 cm from the eye and those who used a computer at a distance of more than 50 cm, as well as between those who never used computers, e-books, and tablets and those who used these devices at a distance of less than 30 cm. Again, a statistical relationship was found between the screen brightness of all the digital display devices and the OSDI scores, except for computer use. In the post hoc analysis, a significant difference was apparent in the use of e-books between those who never used them and those who preferred low screen brightness.

Schirmer-I testing was undertaken for the participants with a severe DES grade according to the OSDI scoring and, if clinically suspected, the participants with other DES grades. The mean value of the Schirmer test for the right eye of the 25 participants studied was 12.54 ± 3.93 mm (minimum = 7, maximum = 20), while the mean value for the left eye was 12.44 ± 3.97 mm (minimum = 7, maximum = 20). The Schirmer test was found to be normal in all 25 subjects examined as they were diagnosed with DES below 6 mm (Table 6).

When the TBUT results of the participants who underwent further examination were analysed, we found that the proportion of eyes with a test result of 10 s or less was 40% (n = 10) in both the right and left eyes. According to the Oxford classification with fluorescein staining performed on these subjects, the percentage of those with a score of 0 for both the right and left eyes was 48% (n = 12), 36% (n = 9) for those with a score of 1, and 16% for those with a score of 2 (n = 4); scores of 3 or 4 were not noted.

Discussion

Due to the rapid development of information and communication technologies, digital display devices have become an indispensable part of people’s daily lives. These technologies not only facilitate people’s daily interactions with one another, but can also mediate many leisure activities, such as planning and accomplishing tasks during the day, building social bonds with other people through various social platforms, accessing healthcare providers, and many recreational activities such as games and entertaining.²⁰ According to published data, adults in Turkey spend an average of 7 h and 29 min per day on the internet, 2 h and 51 min on social media, and 3 h and 4 min watching TV. Considering the gender and age distribution of social media users, it is apparent that men use social media more across all age groups, and generally a third of social media users are in the 25–34 age group.²¹

The use of digital display devices has become routine in daily life, and their excessive use has led to the occurrence of various health problems, especially among students and people in younger age groups. DES is one of the public health problems that has emerged with the increasing use of digital screens in recent years and has been defined as a condition in which ocular and non-ocular symptoms occur together. Based on reports by various researchers, the prevalence of symptoms related to DES is estimated to range between 25% and 93%.²²

In our study, we found that the most preferred digital display device among the participants was the smartphone, and as a health problem, 74.1% of the participants experienced light sensitivity in the eyes with varying frequency (sometimes to always) during the week, 52.2% felt a burning sensation in their eyes, and 72.9% complained of pain or tingling in their eyes. This is in line with the findings of other studies in the literature that have investigated the possible effects of digital display devices on eye health.

The 2 main causes of DES are considered to be tear deficiency (aqueous humour deficiency) and dry eye due to evaporation, although they are not clearly separated.²³ Aqueous-deficient DES is characterized by the lack of secretion of the main and accessory lacrimal glands, while evaporative DES is characterized by a decrease in tear volumes and tear stabilization due to excessive evaporation from the ocular surface. Excessive evaporation of tear fluid due to a reduced number of blinks when digital screen users are focussing has been recognized as an important causal factor for dry eyes associated with digital screen use.²⁴

In an animal model developed by Nakamura et al. to simulate computer use characterized by a reduction in the number of blinks and a constant static posture during daily routines, similar to the results reported by computer users, blink frequency was shown to be 3 times lower among oscillating mice than non-oscillating mice.²⁵ The researchers found that the formation of oscillations plays a critical role in decreasing tear secretion and that the created dry eye condition plays a possible role in accelerating this decrease.²⁶

DES is known to be one of the most common causes of ocular morbidity. The incidence and diagnostic criteria of DES remain complex, as most of the assessment tools currently used for diagnosis are clinically oriented, and their use in community-based settings is uncertain.²⁷ For this reason, symptom assessment is now recognized as an important component of the diagnosis of dry eye. A study supporting the potential utility of this approach has shown that screening based only on symptoms is better at distinguishing cases than screening based on symptoms and diagnostic markers.²⁸ It was concluded that dry eye clinical trials should include an assessment of subjective symptoms and functional lifestyle using a well-designed and validated questionnaire and that such an instrument could be a good measure for determining the clinical effectiveness of therapeutic interventions.²⁷ For these reasons, a large number of dry eye questionnaires have been developed for use by clinicians to diagnose dry eye and assess ocular surface health. The most commonly used questionnaire, the use of which was also recommended in the workshop report TFOS DEWS II, is the OSDI questionnaire developed by the Outcomes Research Group. The OSDI questionnaire captures ocular symptoms compatible with dry eye and can provide a rapid assessment of the functional relationship of these symptoms with vision.²⁹ In 1 study, the OSDI was found to have good sensitivity and specificity in discriminating between normal subjects and patients with dry eye and to be highly statistically correlated with questionnaires such as the McMonnies questionnaire and NEI VFQ-25. In addition, the researchers reported that the OSDI had high internal consistency (CR value, 0.77) and good-to-excellent test–retest reliability (consistency/stability coefficient) when tested between the patient group and normal controls.²⁸

In the study by Irkec et al. in which they evaluated the reliability and validity of the Turkish translation of the OSDI, the sensitivity and specificity of the translation were reported to be 100% and 67%, respectively. In addition, it was found that the Turkish translation of the OSDI, which we used to evaluate ocular symptoms in our study, can be easily used in clinical practice and studies in Turkey to diagnose DES.³⁰

Today, it is very common to use the OSDI questionnaire in studies to detect DES, which is thought to result from the use of digital display devices. The TFOS DEWS II report states that if the results of the OSDI questionnaire completed after anamnesis and triage questions are clinically suspicious, a diagnosis of dry eye can be made without further diagnostic testing. The OSDI is a scale specifically for DES and asks patients about the frequency of certain symptoms and their impact on visual function. The OSDI also allows physicians to differentiate ocular surface disease from other conditions and to obtain an idea of the severity of the disease by categorizing existing DES into normal, mild, moderate, and severe DES. The OSDI questionnaire is considered a unique tool for screening DES in the general population and for detecting the aetiology of the syndrome in individuals.

In a study using the OSDI questionnaire, the average OSDI score was 31.0 ± 15.0 for the participants aged 20–40 years who spent most of their daily lives in front of a computer, and the OSDI score was significantly negatively correlated with the TBUT, Schirmer, and fluorescein staining tests.³¹ In addition, a significant relationship was found between the OSDI score and the duration of computer use. In a study conducted by Moon et al., evaluations were performed before and after cessation of smartphone use for 4 weeks in the DES group. The researchers observed that corneal punctate epitheliopathy decreased from 93.3% to 0% after cessation of smartphone use, and the OSDI score decreased from 30.74 ± 13.36 to 14.53 ± 2.23 points.³²

In our study, the mean value of the participants’ OSDI scores was 25.5 ± 23, which is in line with the results of other studies in the literature. A statistically significant difference was evident based on gender, and this difference can be explained by the hormonal differences between men and women. This difference can be explained by the hormonal differences between men and women. No statistical correlation was found between the participants’ OSDI scores and their ages. The classification of the severity of dry eye symptoms using the OSDI questionnaire revealed that 17.3% of the participants had mild, 20.4% had moderate, and 26.3% had severe dry eye symptoms.

In our study, the participants with severe DES grades based on the OSDI scoring and those clinically suspected participants with other DES grades were subjected to the Schirmer-I test for further evaluation. The Schirmer test was found to be normal in all 25 subjects included in the evaluation, and those with 6 mm in the Schirmer-I test were considered to have DES. When we assessed the TBUT results of the participants who underwent further examination, we found that the proportion of eyes with a test result of 10 s or less was 40% (n = 10) in both the right and left eyes. Based on the Oxford scoring classification, in the participants in whom fluorescein staining was performed, 48% had a score of 0, 36% had a score of 1, and 16% had a score of 2 for both the right and left eyes. No score of 3 or 4 was found. These results provide evidence that the use of digital screens is a cause of evaporation in DES, which is consistent with the findings of other studies in the literature.

It is known that the severity of dry eye symptoms increases significantly as the daily use of digital display devices increases. In a study in which the mean age of the participants was 27 years, the mean total duration of digital screen use was 8.65 ± 3.74 h daily, and 95.8% of the study participants had at least 1 ocular symptom related to digital screen use.³³ In our study, there was a statistically significant increase between the daily hours of use and OSDI scores for all the digital display devices studied. It is thought that the decrease in the number of blinks associated with increases in the time spent using devices daily causes tears to evaporate more easily from the ocular surface and thus causes discomfort. Many studies have suggested that factors such as altered blinking behaviours, uncorrected refractive error, overexposure to intense digital screen light, and decreased working distance are associated with digital eye strain.²²

In our study, we found a statistically significant difference between the OSDI scores of the participants with and without refractive errors. However, no statistically significant difference was evident between the OSDI values based on whether the participants wore permanent glasses or not. According to this result, a diagnosis of eye disease can be considered a risk factor.

No studies in the literature have explained the relationship between working distance and dry eye symptoms. Notwithstanding, the results of our study showed that the OSDI scores increased with decreasing distance among the participants who used computers, e-books, and tablets.

Limitations

Our study has some limitations. First of all, the fact that the study was conducted in a single centre means that the results cannot be generalized to all medical faculty students. Second, because the study design was retrospective, the general follow-up of students who might develop some eye problems due to the use of digital screens could not be determined. Prospective, cohort studies are needed. Third, some confounding factors that may affect study results may have been overlooked.

Conclusion

The widespread use of digital screens has become an important public health problem that has caused an increase in DES in society. In our study, we determined that the rate of DES was higher among the medical school students who used digital imaging devices compared with those who did not. Since the use of digital imaging devices has become an intrinsic part of university education, and the number of devices with digital screens has increased exponentially, especially among younger populations, it is very important to screen for DES in order to raise awareness and to have the opportunity for early treatment. The OSDI questionnaire can be considered a safe tool for the early detection, early diagnosis, and early interventions for DES and can be easily used by family physicians to aid in the diagnosis of DES and help prevent vision-related loss of quality of life.

Funding

None declared.

Authors’ contributions

ESU and MB designed and conceptualized the study. ESU and BU performed the study, and processed the data. ESU and MB conducted the analyses. ESU and BU drafted the manuscript. MB supervised. ESU and MB wrote the paper, discussed the results, and commented on the manuscript.

Ethical approval

Ethics committee approval was obtained from Atatürk University Faculty of Medicine Clinical Research Ethics Committee with the decision number 27/06/2019/05-03.

Conflict of interest

None declared.

Data availability

The data underlying this article will be shared on reasonable request to the corresponding author.

References