title: Small effect of interline spacing on maximal reading speed in low-vision patients with central field loss irrespective of scotoma size.
abstract: OBJECTIVE
  It has been suggested that crowding, the adverse low-level effect due to the proximity of adjacent stimuli, explains slow reading in low-vision patients with absolute macular scotomas. According to this hypothesis, crowding in the vertical dimension should be released by increasing the vertical spacing between lines of text. However, studies with different experimental paradigms and only a few observers have given discrepant results on this question. The purpose of this study was to investigate this issue with a large number of patients whose macular function was carefully assessed.
  
  
  METHODS
  MP1 microperimetry examination was performed for each low-vision patient. Only eyes with an absolute macular scotoma and no foveal sparing (61 patients with AMD, 90 eyes; four patients with Stargardt disease, eight eyes) were included. Maximal reading speed was assessed for each eye with French sentences designed on the MNREAD test principles.
  
  
  RESULTS
  The effect of interline spacing on maximal reading speed (MRS) was significant although small; average MRS increased by 7.1 words/min from standard to double interline spacing. The effect was weak irrespective of PRL distance from the fovea and scotoma area and regardless of whether an eccentric island of functional vision was present within the scotoma.
  
  
  CONCLUSIONS
  Increasing interline spacing is advisable only for very slow readers (<20 words/min) who want to read a few words (spot reading). Vertical crowding does not seem to be a major determinant of maximal reading speed for patients with central scotomas.
authors.affiliation: Université Aix-Marseille II, Institut de Neurosciences Cognitives de la Méditerranée, CNRS, Marseille, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Calabrèse
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Bernard
authors.forename: Louis
authors.initials: L
authors.lastname: Hoffart
authors.forename: Géraldine
authors.initials: G
authors.lastname: Faure
authors.forename: Fatiha
authors.initials: F
authors.lastname: Barouch
authors.forename: John
authors.initials: J
authors.lastname: Conrath
authors.forename: Eric
authors.initials: E
authors.lastname: Castet
mesh_terms: D000328:Adult; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008875:Middle Aged; D011594:Psychometrics; D011932:Reading; D012607:Scotoma / Q000503:physiopathology*; D014787:Vision Tests; D015354:Vision, Low / Q000503:physiopathology*; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult