Dry eye disease is defined by the Report of the Definition and Classification Subcommittee of the International Dry Eye WorkShop as a multifactorial disease of the tears and ocular surface, which results in symptoms of discomfort, visual disturbance, and tear film instability, with potential damage to the ocular surface.1 The prevalence of dry eye disease is estimated to be 7.4% to 33.7%, depending on the diagnostic criteria used and population surveyed.2 Dry eye disease is known to increase with old age, and is not common in children because most of the factors involved in the pathophysiology of dry eye disease are more common in adults.3 Thus, there have been limited studies of the prevalence and characteristics of dry eye disease in children.3–5 Children have less ability to express discomfort than adults, and even if they express discomfort, the diagnosis of dry eye disease requires the cooperation of the patient for examination and assessment of subjective symptoms.3 Additionally, the prevalence of allergic conjunctivitis is high in children, and allergic conjunctivitis commonly coexists with dry eye disease.3,6 Thus, the differential diagnosis of allergic conjunctivitis and dry eye disease is sometimes difficult, especially in children.7 For these reasons, the significance and prevalence of dry eye disease in children may be underestimated and physicians often lack awareness of dry eye disease in children and link it with systemic diseases such as familial dysautonomia, Allgrove syndrome, Sjögren syndrome, and juvenile rheumatoid arthritis.3,8
There has recently been an increase in the amount of work performed using video display terminals. Use of computer, television, and portable information terminals, including smartphones, has increased, and these changes have been accompanied by an increase in symptoms called video display terminal syndrome, including dry eye disease.9,10 Video display terminal syndrome is not limited to adults because the use of video display terminals has also increased in school children. A recent survey concluded that 66% of children aged 8 to 17 years in the United States preferred the Internet if they could have only one medium of entertainment.11 Changes in lifestyle and entertainment may be risk factors for dry eye disease in children.
In this study, we compared school children with and without dry eye disease and evaluated the risk factors of dry eye disease in school children associated with video display terminal use.
Patients and Methods
The study design was cross-sectional. Relative humidity in this region of Korea during the time of the study ranged from 45% to 67%. Exclusion criteria were: (1) children who underwent any type of eye surgery in the past 6 months, (2) children who had nocturnal lagophthalmos, and (3) children who had eyelid problems (trichiasis, districhiasis, or epiblepharon). We performed ocular examinations of all children in the fifth and sixth grades from one elementary school in Dongjak-gu, Seoul, Korea, in May 2012, at the request of the school. In addition to the ocular examination, we sent letters explaining the purpose of the survey and requested the participation and consent of the children. The questionnaires were composed of questions about dry eye disease and video display terminal use. Twenty-eight children with dry eye disease were included in the dry eye disease group and 260 age-matched children with no evidence of dry eye disease were included in the control group. This study was approved by the Institutional Review Board of the Chung-Ang University Hospital of Korea.
All comprehensive ocular examinations included best-corrected visual acuity tests, slit-lamp examinations of the cornea and conjunctiva, and evaluations of eyelid problems. Tear break-up time (TBUT) was measured with a fluorescein strip (Haag-Streit International, Koeniz, Switzerland) coated with one drop of balanced salt solution (BSS; Alcon Laboratories, Inc., Fort Worth, TX). After applying the strip on the inferior conjunctival fornix, the participant resumed normal blinking for several seconds. After the fluorescein solution spread across the corneal surface, the participant was asked to keep his or her eye open until the first defect of tear film occurred. TBUT was defined as the interval between the last complete blink and the first appearance of a dry spot on the pre-corneal surface of the tear film. The procedure was repeated three times for each eye tested, with results reported as the mean value of the three measurements.
Punctate epithelial erosions in the corneal conjunctiva were evaluated by a single examiner using a slit lamp according to the Oxford Scheme Panel.12 The slit-lamp examiner was masked to the results of the survey to reduce bias. In addition, we recorded the presence or absence of papillae or follicles in conjunctiva. Eyelid problems were also evaluated. Rose bengal staining was performed to exclude children who had nocturnal lagophthalmos. We applied a rose bengal strip with one drop of balanced salt solution on the inferior fornix and confirmed conjunctival staining of nocturnal lagophthalmos.13
A self-administered questionnaire was designed for obtaining information about risk factors for dry eye disease in school children, including video display terminal use and subjective ocular signs. The questionnaire consisted of the following items: (1) video display terminal use: computers, smart-phones, television, and use time per day; (2) mean duration of daily night sleep; (3) ocular symptoms for dry eye: Do you feel dry (not wet enough?), Do your eyes feel irritated?, Do you feel visual fatigue?, Do you feel an itching sensation?, Do you have headaches?; and (4) whether ocular symptoms are aggravated with the use of video display terminals such as computers, smartphones, or television.
Diagnosis of Dry Eye Disease
Dry eye disease was defined based on the DEWS Definition and Classification of 2007 by symptoms evaluated with the study questionnaire: discomfort (dryness or irritation) or visual symptoms (fatigue) associated with at least one objective parameter (TBUT less than 10 seconds or positive corneal and conjunctival fluorescein staining quantified according to the Oxford Scale) (Table 1).12 If children showed unilateral dry eye disease, they were included in the dry eye disease group.
Dry Eye Disease Diagnostic Criteria
Statistical analyses were performed using SPSS for Windows (version 18.0; SPSS, Inc., Chicago, IL). Continuous variables were compared between groups using the Student’s t test. The chi-square test was used to compare noncontinuous variables between the two groups. To assess the effects of risk factors, including video display terminal use, on dry eye disease, Pearson rank correlation coefficients were calculated by linear regression analysis. P values of less than .05 were considered statistically significant.
Dry eye disease has shown a marked increase due to video display terminal use and has become a significant health issue affecting the quality of life in industrialized countries.14 Dry eye disease associated with the use of video display terminals can be multifactorial and is still not well understood.15 Decreased blinking and increased interpalpebral ocular surface area during use of video display terminals may increase tear evaporation due to destabilization of the tear film.16
A smartphone is a portable information terminal that is used not only for telephone calls but also as a small handheld computer. In Korea, 50.41% of the adult population uses smartphones and the mean duration of smartphone use is reported to be 1.9 hours per day. There are no data regarding smartphone use in children, but it is known to be increasing. In the current study, 52.1% of children among 288 elementary school children aged 9 to 11 years reported using smartphones.
We evaluated the characteristics and risk factors of dry eye disease in children. Dry eye disease is more commonly found in females with adult dry eye disease,17 but there were no significant differences in gender distribution between the dry eye disease group and control group in our study. Mean daily duration of sleep, also known as a risk factor for dry eye disease in adults,4,18 did not show significant differences between the two groups in our study, but this may be due to lack of variation in sleeping duration in children. The characteristics of dry eye disease in children may be similar to or may have different features than dry eye disease in adults.
Among our participants, all of the children used computers and televisions and 52.1% used smartphones. The results revealed that the use of smartphones, the mean duration of smartphone use, and the mean duration of total video display terminal use were risk factors for dry eye disease in children. Interestingly, the daily duration of computer and television use alone was not associated with increases in dry eye disease, but children who used both smartphones and computers reported more ocular symptoms, including visual fatigue, dryness, and headache.
The significance of smartphone use as a risk factor for dry eye disease in children has not previously been recognized. Our results indicate that dry eye disease in children is a clinically significant problem. All of the children in the dry eye disease group complained of visual fatigue, and more than half complained of dryness, headache, and burning sensations. Such subjective symptoms may affect quality of life. Punctate epithelial erosions were found in 100% of the dry eye disease group; such ocular surface complications require treatment and decrease visual acuity. In addition, surface irregularities on the cornea can aggravate tear film instability.19
Limitations of our study include the following. Children and their parents who answered the questions regarding duration of sleep and video display terminal, television, and computer use assumed a correlation between video display terminal use and ocular problems. A research bias was that parents may have guessed the reason for our study before answering the questionnaire. Additionally, the age range was limited to 9 to 11 years, and therefore our study results may not represent the full extent of dry eye disease in children. We also did not evaluate all types of video display terminals, only the video display terminals most commonly used by children.
In our study, allergic conjunctivitis was significantly more common in the dry eye disease group, confirming previous findings in the literature.20 However, this finding may reflect a limitation of our study in that children with allergic conjunctivitis were included. Allergic conjunctivitis aggravates ocular dryness by exacerbating the inflammatory reaction on the ocular surface. Spring and fall are peak allergic season in Korea, and would include confounding anterior segment problems for these eyes. Ocular allergy was noted to be a risk factor for dry eye disease in the Beaver Dam Study, although the concomitant use of systemic medications such as antihistamines was recognized as a potential contributor.4,9 However, there was no statistically significant clinical aggravation in our study between participants with dry eye disease and allergic conjunctivitis and participants with dry eye disease only. There was no statistically significant difference between the two groups regarding time of video display terminal use. There were no children with severe allergic conjunctivitis in our study, but allergic conjunctivitis may have biased evaluations of the relationship between video display terminal use and dry eye disease.
The prevalence of dry eye disease in children is known to be lower than in adults, but should not be dismissed as a minor problem.2,17 Many children express ocular discomfort such as dryness, irritation, and fatigue, but it can be challenging to obtain samples of tears from children and is difficult to distinguish these symptoms from those caused by allergic conjunctivitis.
In our study, 9.7% of children were diagnosed as having dry eye disease and video display terminal use was more common in the dry eye disease group. Although the children in our study felt that computer use resulted in greater experiences of subjective symptoms than the use of smartphones, our results showed that smartphone use is a greater risk factor than computer use in children.
Close observation and caution when using video display terminals, especially smartphones, is needed for children. Smartphones are used not only for telephone calls, but also for gaming, Internet searches, and entertainment, and use time per day may increase as children become older. Increased use of smartphones could result in other ocular problems due to near visual tasking. Long-term use of near visual tasking may affect accommodation and lead to progression of myopia.21,22 Transient myopia induced by near work may contribute to the development and progression of permanent myopia.21,23,24 Thus, children with high levels of video display terminal use should undergo routine examinations and treatment to preserve ocular health. Dry eye disease in children must be detected early, and should be treated with appropriate medical and environmental manipulations and education.