The effect of sustained VDU and Non-VDU nearwork on visual acuity and refractive error in emmetropic primary schoolchildren

  • Teoh Swee Chai School of Optometry, National Institute of Ophthalmic Sciences (academic arm of the Tun Hussein Onn National Eye Hospital), NIO Office, 1st Floor NIO Building, Lot2, Lorong Utara B, 46200 Petaling Jaya, Selangor, Malaysia.
  • Chen Ai-Hong Department of Optometry, Faculty of Health Sciences, Universiti Teknologi MARA
  • Norhani Mohidin Department of Optometry, Faculty of Allied Health Sciences, National University of Malaysia
Keywords: visual acuity, refractive error, visual display unit, myopia


Myopic shift in refraction following a sustained period of near-work is well documented among adult visual display unit (VDU) users. This crossover study investigates the effect of VDU near-work on visual acuity and refractive status among 7-year-old children. Thirty emmetropic and low-hyperopic schoolchildren (refractive error: -0.25DS to +1.25DS, astigmatism ≤ 1.00DC and anisometropia ≤ 1.00D) participated in this study. All subjects (15 males and 15 females) were involved in two 2-hour near-work sessions (at 40 cm), one with and one without a VDU, which were carried out in random sequence on two separate days. Distance visual acuity (monocular/binocular) and subjective refractive error were measured before and immediately after both near-work sessions. MANCOVA analysis showed that VDU work produced a significant myopic shift, -0.10 ± 0.18 D (F1,54 = 5.17, p = 0.03) in distance refractive status. This myopic shift was not found after non-VDU work. There was no significant change in monocular (F1,54 = 0.03, p = 0.86) and binocular visual acuity (F1,54 = 0.22, p = 0.64) after near-work with or without VDU. Emmetropic and low-hyperopic schoolchildren are susceptible to VDU near-work after-effect. Sustained VDU near-work causes significant myopic shift in emmetropic and low-hyperopic 7-year-old children. However, the myopic shift is not accompanied by a reduction in visual acuity.


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