title: Google Glass Glare: disability glare produced by a head-mounted visual display.
abstract: OBJECTIVE
  Head mounted displays are a type of wearable technology - a market that is projected to expand rapidly over the coming years. Probably the most well known example is the device Google Glass (or 'Glass'). Here we investigate the extent to which the device display can interfere with normal visual function by producing monocular disability glare.
  
  
  METHODS
  Contrast sensitivity was measured in two normally sighted participants, 32 and 52 years of age. Data were recorded for the right eye, the left eye and then again in a binocular condition. Measurements were taken both with and without the Glass in place, across a range of stimulus luminance levels using a two-alternative forced-choice methodology.
  
  
  RESULTS
  The device produced a significant reduction in contrast sensitivity in the right eye (>0.5 log units). The level of disability glare increased as stimulus luminance was reduced in a manner consistent with intraocular light scatter, resulting in a veiling retinal illuminance. Sensitivity in the left eye was unaffected. A significant reduction in binocular contrast sensitivity occurred at lower luminance levels due to a loss of binocular summation, although binocular sensitivity was not found to fall below the sensitivity of the better monocular level (binocular inhibition).
  
  
  CONCLUSIONS
  Head mounted displays such as Google Glass have the potential to cause significant disability glare in the eye exposed to the visual display, particularly under conditions of low luminance. They can also cause a more modest binocular reduction in sensitivity by eliminating the benefits of binocular summation.
authors.affiliation: Bradford School of Optometry and Vision Science, University of Bradford, Bradford, UK.
authors.forename: Chris
authors.identifier: http://orcid.org/0000-0003-2232-4893
authors.initials: C
authors.lastname: Longley
authors.affiliation: Cardiff School of Optometry and Vision Sciences, Cardiff, UK.
authors.forename: David
authors.initials: D
authors.lastname: Whitaker
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D019466:Glare / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000068997:Smartphone; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology; D015348:Vision, Binocular / Q000502:physiology; D015349:Vision, Monocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology
keywords: Google Glass; binocular inhibition; binocular summation; contrast sensitivity; disability glare