title: Peripheral prism glasses: effects of moving and stationary backgrounds.
abstract: OBJECTIVE
  Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance and partial suppression of the prism image, thereby limiting device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared with monocular viewing.
  
  
  METHODS
  Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos.
  
  
  RESULTS
  With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than in monocular (prism eye) viewing on the motion background (medians, 13 and 58%, respectively, p = 0.008) but not the still frame background (medians, 63 and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in one HH and one normally sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing.
  
  
  CONCLUSIONS
  Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations.
authors.affiliation: *OD †MSc, OD, FAAO ‡PhD, MCOptom, FAAO Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts; and New England College of Optometry, Boston, Massachusetts (all authors).
authors.forename: Jieming
authors.initials: J
authors.lastname: Shen
authors.forename: Eli
authors.initials: E
authors.lastname: Peli
authors.forename: Alex R
authors.initials: AR
authors.lastname: Bowers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001334:Automobile Driving; D005139:Eyeglasses; D005260:Female; D006301:Health Services Needs and Demand; D006423:Hemianopsia / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology