TOKYO -- Doctors have conducted investigations following concerns that widespread use of tablets and smartphones may be fuelling an increase in cases of acute esotropia among children. Symptoms of esotropia include when one or both eyes turn inward and do not return to their neutral position.
Hamamatsu University Hospital in Hamamatsu, Shizuoka Prefecture, southwest of Tokyo, has recorded a noticeable rise in the number of parents bringing children with the condition for examination. The hospital says it used to see two to three patients a year with esotropia, but since three years ago that number has shifted to around 10 annually.
The main symptoms include diplopia, also known as double vision, as a result of the position of the eyes not matching one another and diplopia, which creates difficulties in depth perception and perspective, Factors such as brain irregularities, stress or strong myopia can cause sudden development of symptoms, but suspicions that digital devices are triggering cases have become more common recently.
In January 2018, a research group at the National Center for Child Health and Development in Tokyo announced a paper detailing the results of its analysis of seven patients with acute onset or worsening esotropia aged between 6 and 17 years who were examined by ophthalmologists at the center in the period 2014 to 2016.
In all cases, the patients spent over three to four hours a day on devices including smartphones, tablets and portable games consoles. The report reads, "There is a possibility that the overuse of ICT (Information and Communications Technology) devices causes and exacerbates esotropia symptoms." The Japanese Association for Strabismus and Amblyopia (JASA) has joined hands with the Japanese Association of Pediatric Ophthalmology in conducting a survey that begun at the end of December 2018 on 1,000 doctors across the country.
According to Miho Sato, president of JASA and hospital professor in strabismus and pediatric ophthalmology at Hamamatsu University Hospital, many people bring the devices right up to their face to look at them, causing the eyes to draw in close together to focus on the screen. She said it is thought that if allowed to continue for a long period, the non-dominant eye struggles to return to its normal position.
She added that the brain fully develops its ability to perceive depth through both eyes at around the age of 5. If symptoms show before then, there is a possibility that the brain's motor skills and other functions have been damaged during development.
"Children have a lot of free time. Moreover, it's hard for their eyes to get tired and their focal powers are very strong. I guess that's why (a growing number of children show symptoms of esotropia)," Sato posited. Placing the emphasis back on digital devices, she said "We must immediately shed light on the causal relationship with screen electronics."
(Japanese original by Hiroyuki Wada, Integrated Digital News Center)