Dry eyes and smartphone use
BEYOND their expressive power, tears keep the human eyes healthy. According to the American Academy of Ophthalmology, every time someone blinks, a film of tears spreads over the eyes, making the surface of the organs smooth and clear.
Three layers form the film: oily layer, watery layer and mucus layer. The oily layer, situated outside the tear film, smoothens the tear’s surface and prevents tears from drying up too quickly. The middle layer is the watery layer, and it makes up most of what humans see as tears. Its function is to remove the particles that are not supposed to be in the eyes. The mucus layer helps spread the watery layer over the eye’s surface to keep it moist. This inner layer ensures that the tears stick to the eyes.
“Normally, our eyes constantly make tears to stay moist. If our eyes are irritated, or we cry, our eyes make a lot of tears. But, sometimes the eyes don’t make enough tears or something affects one or more layers of the tear film,” the association says. “In those cases, we end up with dry eyes.”
Dry eye disease may not be fatal, but it is surely unpleasant. One feels a stinging sensation in the eyes and as if something’s stuck in there. The eyes redden. They become watery and painful. The eyelids get heavy, the vision blurry.
Some of the factors that raise one’s risk of having dry eyes are ageing, being a woman, medications like antihistamines and antidepressants, use of contact lenses, exposure to smoke and a dry environment. A case control study published late last year in the journal BMC Ophthalmology found that smartphone use could be another risk factor. The authors of the study, Jun Hyung Moon, Kyoung Woo Kim and Nam Ju Moon, investigated the risk and protective factors associated with pediatric dry eye disease (DED) in relation to smartphone use rate according to region and age.
They performed ophthalmologic examinations on 630 children from eight primary schools in Seoul, South Korea and 286 children in Paju, Korea, for a total of 916. Those ocular exams were visual acuity tests, autokeratomery, slit- lamp examinations of the cornea and conjunctiva, and evaluation of eyelid problems, allergic conjunctivitis, and exposure keratitis.
The researchers also gave the children and their parents questionnaires to answer. Those questionnaires were designed to obtain information regarding risk factors for dry eye disease, including the mean daily duration of video display terminal ( smartphone, computer, television) use, learning (reading and writing), outdoor activities, and past history of allergic disease and antihistamine drug use.
Participants were divided into several groups: DED vs. control, urban vs. rural, younger grade (1st to 3rd) vs. older grade (4th to 6th). The researchers discovered that the DED rate in all children was 6.6%, that the mean daily duration of smartphone use was longer in the DED group than in the control group, and that the mean daily duration of outdoor activities was shorter in the DED group that in the control group.
An 8.3% of children in the urban group were diagnosed with DED compared to 2.8% in the rural group. Rates of smartphone use in urban and rural groups were 61.3% and 51%, respectively. Meanwhile, 9.1% of the participants in the older- age group were diagnosed with DED compared to 4% in the youngerage group. Both older- age (65.1%) and younger-age groups ( 50.9%) also had high rates of smartphone use.
“Smartphone use in children was strongly associated with pediatric DED; however, outdoor activity appeared to be protective against pediatric DED. Older-grade students in urban environments had DED risk factors ( long duration of smartphone use), and a short duration of outdoor activity time. Therefore, close observation and caution are needed when older children in urban areas use smartphones,” the authors concluded.
“Normally, our eyes constantly make tears to stay moist. If our eyes are irritated, or we cry, our eyes make a lot of tears. But, sometimes the eyes don’t make enough tears or something affects one or more layers of the tear film. In those cases, we end up with dry eyes.”