During the COVID-19 pandemic, university students, including medical students, had to shift most study programs to online platforms. This study ascertained the prevalence of DED in young people and its associated factors, along with its impact on QoL during the pandemic. This online survey was conducted during the third wave of the COVID-19 pandemic in Thailand in 2022 and the prevalence of DED among medical students was 60.4%, determined using the DEQS-Th questionnaire. This figure was comparatively lower than those reported in previous studies conducted among high school students and university students during the early onset of the pandemic, where prevalence ranged from 70.5–77.5%. 17,26,27 These variations may partly differ due to the diagnostic criteria for DED across studies, as well as the timing of the research. However, it is noteworthy that the prevalence of DED among this specific young population remains high across all studies compared to the pre-COVID-19 era (8.2–26.6%).13,14,28
The use of digital devices for education such as laptops, tablets, mobile phones, e-readers, as well as video conference platforms has increased since the pandemic. Previous studies found an association between VDT use and DED among young adults and children, including primary school students.10–12 In addition, VDT use increased significantly in comparison to before the pandemic. 17 Although the average screen time in this study was high (> 10 hours/day), there was no significant difference between DED and non-DED participants. This might be because digital devices have been increasingly used in the past decade and have become a norm in people’s lifestyles. Excessive exposure to VDT can lead to the deterioration of dry eye symptoms. 29 While using digital screens, or when paying attention to something, the blink rate usually decreases, or incomplete blinking occurs which leads to an increase in tear evaporation and tear film instability. 12,30 In addition, prolonged use of digital devices or exposure to screen illumination (> 4 hours) may contribute to ocular surface-related symptoms such as burning sensation, grittiness, watering, itching, dryness, and eye fatigue known as “digital eye strain (DES)”, which may overlap with dry eye symptoms.31 DES symptoms can be accommodation-related such as difficulty refocusing from one distance to another, or can be extraocular symptoms such as headache, neck or shoulder, and back pain.31 Moreover, myopic progression has been linked to DES in the pediatric population.32 Thus, both DES and DED are associated with prolonged screen exposure and may co-occur. Uwimana et al found a concurrent rise of DES and DED symptoms with a strong and significant positive correlation between both conditions (r = 0.695, p < 0.001) among university students during the COVID-19 pandemic. 33
Other known associated risk factors for DED include female gender, contact lens use, and allergic diseases.8,34 However, only preexisting dry eye and refractive error correction with spectacles were statistically significantly associated factors for DED in this study. Although we found that female students were predominant in the DED group, the difference was not statistically significant. Among the students using glasses to correct refractive error, particularly individuals with improper correction, using accommodation may lead to ocular symptoms (i.e. eye pain, strain, and discomfort), which overlap with dry eye symptoms.12,17 Our findings are contrary to previous evidence that contact lens use is a consistent risk factor for DED in students.9,10,13 This is probably due to a relatively small population of contact lens wearers among our study population that might affect the analysis.
During the pandemic, a face mask became the most common personal prevention equipment to protect against viral infection. Various studies found evidence to show an increase in dry eye symptoms and ocular discomfort related to face mask users. The incidence of mask-associated dry eye (MADE) varied from 7.9–18.3%. 35,36 The possible pathophysiological mechanisms associated with MADE may be related to an unnatural upward airflow towards the ocular surface during expiration leading to increased tear evaporation and inducing stress which may increase in improperly fitted face masks. 36,37
This study found that the surgical mask was the most common type of mask used (85%) in all students and there was no significant difference in mean mask-wearing time among the DED and non-DED students with overall mask-wearing time was more than 8 hours/day. This may be because medical students might have been trained in proper mask-wearing as they needed to wear masks for their work.
Evidence showed that symptoms of DED can significantly impair visual function, limit activities, and reduce work productivity.2,4,5,7 Our previous study demonstrated a significant association between perceived stress, neuroticism, and QOL in DED patients.38 In addition, the personality of the patients may influence the symptoms and QOL in DED patients.38 During the pandemic, stress levels and sleep disturbance have been identified as factors exacerbating dry eye symptoms, along with a decrease in pain threshold and inflammation.18 Lin et al studied high school students in China and found that apart from prolonged VDT use and female gender, stress and poor sleep quality were factors significantly associated with DED during the COVID-19 outbreak.27 Increased online studying and a decrease in normal learning activities may heighten stress levels beyond typical circumstances, potentially leading to increased stress and depression among medical students. In this study, DED symptoms exhibited a significant negative correlation with QOL and mental health, particularly regarding perceived stress and depression, although these correlations were not strong. Our findings underscore that DED is among the ocular disorders that significantly affect the QOL and mental well-being of an individual. In a younger population, chronic dry eye symptoms and impaired mental health may potentially affect the learning ability of individuals as well as their personalities. However, further studies are needed to explore these relationships.
The main strength of this study lies in the use of validated questionnaires with adequate psychometric properties to assess DED symptoms, in addition to QOL and mental health. Participants voluntarily and anonymously completed the survey. The results of this study will enable clinicians and carers to become aware of this ocular problem, which can significantly impact the QOL of students. However, this study also has some limitations. Firstly, it was conducted during the pandemic using an online platform, lacking clinical evaluations for DED such as tear film break-up time, ocular surface staining, or the Schirmer test. Thus, asymptomatic DED participants may have been overlooked. Furthermore, a reliance on self-conducted questionnaire surveys might introduce recall bias. This study is a cross-sectional study, and further investigations are required to determine the causal relationship between individual risk factors and DED.
In conclusion, the prevalence of symptomatic DED among medical students was notably high during the COVID-19 pandemic. Significant associated factors for DED in this young population included preexisting DED and the use of spectacles for correction of refractive errors. Interestingly, female gender, ocular allergy, contact lens wear, screen time, and mask-wearing were not significantly associated with DED. Dry eye symptoms had adverse effects on both quality of life and mental health, particularly regarding perceived stress, and depression. Our findings may contribute to the development of preventive and management strategies to identify students at risk and mitigate the consequences of chronic DED.