title: Fixation stability using radial gratings in patients with age-related macular degeneration.
abstract: BACKGROUND
  The fixation stability of patients with macular atrophy is generally worse than that of people without pathology.
  
  
  METHODS
  The effects of 2 types of high-contrast fixation stimuli on fixation stability were compared between patients with longstanding age-related macular degeneration (AMD) and control subjects with normal vision. One stimulus was a 9-cycle square-wave radial grating measuring 5 degrees in diameter and the other a white 0.5 degrees disc. A video-based infrared eye tracker with remote optics was used to record eye position while participants fixated the stimuli in primary position of gaze for 6 to 7 s. Fixation stability was measured with a bivariate contour ellipse area (BCEA).
  
  
  RESULTS
  For patients with AMD, fixation stability for the radial grating was largely independent of visual acuity, whereas fixation stability for the disc diminished with acuity. For the control observers, there were no differences in fixation stability for the 2 kinds of stimuli.
  
  
  CONCLUSIONS
  In clinical and research settings, radial gratings can be useful targets for fixation for patients with macular disease since they provide enough visual information to help maintain fixation stability. These findings have important implications for the design of clinical tests and procedures such as perimetry, multifocal electroretinography, and optical coherence tomography for patients with macular atrophies.
authors.affiliation: Centre for Vision Research, York University, Toronto, ON, Canada. gonzalez@yorku.ca
authors.forename: Esther G
authors.initials: EG
authors.lastname: González
authors.forename: Joshua
authors.initials: J
authors.lastname: Teichman
authors.forename: Linda
authors.initials: L
authors.lastname: Lillakas
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Markowitz
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Steinbach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015350:Contrast Sensitivity / Q000502:physiology; D003941:Diagnostic Techniques, Ophthalmological; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008875:Middle Aged; D010781:Photography; D014792:Visual Acuity / Q000502:physiology