Computer screens, rather than mobile phones or tablets, are a main cause of the myopia epidemic according to a new study from The University of Western Australia.
Senior research fellow Samantha Sze-Yee Lee, from the Lions Eye Institute used data collected from 624 young adults, part of the Raine Study, to discern the types of digital screens that contributed to the development of myopia.
Dr Lee found that short-sightedness worsened faster in those who reported six or more hours per day of computer usage compared with those with low computer use, while time spent on mobile phones did not have any effect.
“The reason for this difference may be due to a phenomenon called ‘peripheral defocus’,” Dr Lee said.
“When you look at your mobile phone, everywhere in our peripheral vision, with the exception of the small phone screen, is further away and relatively blurred.
“The brain registers things are generally far away and there is no need for the eye to become more short-sighted.
“When you focus on a large screen such as a desktop computer, more of our peripheral vision is taken by the screen. The brain sees that more short-distance work is involved, triggering the eyes to become more short-sighted.”
Dr Lee’s research also confirmed that less sun exposure and genetic disposition were the other major risk factors for myopia.
“It is hoped the findings will help scientists develop techniques to mitigate the detrimental impact of computer screens on eyesight.”
Study Method
Based in Perth, Western Australia, the Raine Study is one of the largest and longest-running studies of human health from pregnancy through childhood, adolescence, and adulthood to be carried out anywhere in the world.
To conduct the research, Dr Lee’s team took spherical equivalent refraction (SER) and axial length (AL) measurements for 624 Raine Study participants at 20 years old (baseline) and 28 years old. Participants were genotyped and their polygenic scores (PGS) for refractive error calculated. Self-reported screen time data (computer, television, and mobile devices) from 20 to 28 years old, was collected prospectively with longitudinal trajectories generated. Additionally, the researchers quantified sun exposure using conjunctival ultraviolet autofluorescence (CUVAF) area.
They reported that sex, baseline myopia, parental myopia, screen time, CUVAF, and PGS were significantly associated with myopic shift.
“Collectively, these factors accounted for approximately 20% of the variance in refractive error change, with screen time, CUVAF, and PGS each explaining approximately 1% of the variance.
“Myopic shift was faster in those with ‘consistently high’ or ‘consistently very high’ screen time compared to ‘consistently-low’ (P ≤ 0.031). For each z-score increase in PGS, changes in SER and AL increased by −0.005 D/year and 0.002 mm/year (P ≤ 0.045). Of the three types of screen time, only computer time was associated with myopic shift (P ≤ 0.040). There was no two- or three-way interaction effect between PGS, CUVAF, or screen time (P ≥ 0.26).”
Findings May Help Mitigate Computer Impact
With myopia being associated with increased risk of future eye problems, such as glaucoma and retinal degeneration, Dr Lee said it is important that we understand how our modern world affects our risk.
“In this day and age, it is almost impossible to avoid digital screens,” Dr Lee said.
“Mobile phones can easily be used outdoors, as opposed to laptop and desktop computers, and spending more time outdoors is known to be protective against myopia.
“It is hoped the findings will help scientists develop techniques to mitigate the detrimental impact of computer screens on eyesight.”
