title: Driving with central field loss I: effect of central scotomas on responses to hazards.
abstract: OBJECTIVE
  To determine how central field loss (CFL) affects reaction time to pedestrians and to test the hypothesis that scotomas lateral to the preferred retinal locus will delay detection of hazards approaching from that side.
  
  
  METHODS
  Participants with binocular CFL (scotoma diameter, 7°-25°; visual acuity, 0.3-1.0 logMAR) using lateral preferred retinal fixation loci and matched controls with normal vision drove in a simulator for approximately 1½ hours per session for 2 sessions a week apart. Participants responded to frequent virtual pedestrians who appeared on either the left or right sides and approached the participant's lane on a collision trajectory that, therefore, caused them to remain in approximately the same area of the visual field.
  
  
  RESULTS
  The study included 11 individuals with CFL and 11 controls with normal vision. The CFL participants had more detection failures for pedestrians who appeared in areas of visual field loss than did controls in corresponding areas (6.4% vs 0.2%). Furthermore, the CFL participants reacted more slowly to pedestrians in blind than nonscotomatous areas (4.28 vs 2.43 seconds, P < .001) and overall had more late and missed responses than controls (29% vs 3%, P < .001). Scotoma size and contrast sensitivity predicted outcomes in blind and seeing areas, respectively. Visual acuity was not correlated with response measures.
  
  
  CONCLUSIONS
  In addition to causing visual acuity and contrast sensitivity loss, the central scotoma per se delayed hazard detection even though small eye movements could potentially compensate for the loss. Responses in nonscotomatous areas were also delayed, although to a lesser extent, possibly because of the eccentricity of fixation. Our findings will help practitioners advise patients with CFL about specific difficulties they may face when driving.
authors: The Schepens Eye Research Institute, Boston, MA 02114, USA. matthew.bronstad@schepens.harvard.edu
authors: P Matthew
authors: PM
authors: Bronstad
authors: Alex R
authors: AR
authors: Bowers
authors: Amanda
authors: A
authors: Albu
authors: Robert
authors: R
authors: Goldstein
authors: Eli
authors: E
authors: Peli
mesh_terms: D000063:Accidents, Traffic; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001334:Automobile Driving; D003198:Computer Simulation; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology*; D012607:Scotoma / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology; D015354:Vision, Low / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception