title: Accommodation in astigmatic children during visual task performance.
abstract: OBJECTIVE
  To determine the accuracy and stability of accommodation in uncorrected children during visual task performance.
  
  
  METHODS
  Subjects were second- to seventh-grade children from a highly astigmatic population. Measurements of noncycloplegic right eye spherical equivalent (Mnc) were obtained while uncorrected subjects performed three visual tasks at near (40 cm) and distance (2 m). Tasks included reading sentences with stimulus letter size near acuity threshold and an age-appropriate letter size (high task demands) and viewing a video (low task demand). Repeated measures ANOVA assessed the influence of astigmatism, task demand, and accommodative demand on accuracy (mean Mnc) and variability (mean SD of Mnc) of accommodation.
  
  
  RESULTS
  For near and distance analyses, respectively, sample size was 321 and 247, mean age was 10.37 (SD 1.77) and 10.30 (SD 1.74) years, mean cycloplegic M was 0.48 (SD 1.10) and 0.79 diopters (D) (SD 1.00), and mean astigmatism was 0.99 (SD 1.15) and 0.75 D (SD 0.96). Poor accommodative accuracy was associated with high astigmatism, low task demand (video viewing), and high accommodative demand. The negative effect of accommodative demand on accuracy increased with increasing astigmatism, with the poorest accommodative accuracy observed in high astigmats (≥3.00 D) with high accommodative demand/high hyperopia (1.53 D and 2.05 D of underaccommodation for near and distant stimuli, respectively). Accommodative variability was greatest in high astigmats and was uniformly high across task condition. No/low and moderate astigmats showed higher variability for the video task than the reading tasks.
  
  
  CONCLUSIONS
  Accuracy of accommodation is reduced in uncorrected children with high astigmatism and high accommodative demand/high hyperopia, but improves with increased visual task demand (reading). High astigmats showed the greatest variability in accommodation.
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States College of Public Health, University of Arizona, Tucson, Arizona, United States.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Harvey
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Miller
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Howard P
authors.initials: HP
authors.lastname: Apple
authors.affiliation: Department of Internal Medicine, University of Arizona, Tucson, Arizona, United States.
authors.forename: Pavan
authors.initials: P
authors.lastname: Parashar
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States College of Public Health, University of Arizona, Tucson, Arizona, United States.
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Twelker
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Mabel
authors.initials: M
authors.lastname: Crescioni
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Davis
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Tina K
authors.initials: TK
authors.lastname: Leonard-Green
authors.affiliation: Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, United States.
authors.forename: Irene
authors.initials: I
authors.lastname: Campus
authors.affiliation: College of Public Health, University of Arizona, Tucson, Arizona, United States.
authors.forename: Duane L
authors.initials: DL
authors.lastname: Sherrill
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000704:Analysis of Variance; D001251:Astigmatism / Q000503:physiopathology*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D011932:Reading; D012684:Sensory Thresholds / Q000502:physiology; D013647:Task Performance and Analysis; D014792:Visual Acuity / Q000502:physiology
keywords: accommodation; astigmatism; children
references.citation: Vision Res. 1975 Apr;15(4):483-92
references.pmid: 1129995
references.citation: Vision Res. 2007 Feb;47(3):315-26
references.pmid: 17184807
references.citation: Optom Vis Sci. 2006 Apr;83(4):206-12
references.pmid: 16614575
references.citation: Am J Ophthalmol. 2006 Jul;142(1):68-74
references.pmid: 16815252
references.citation: J Opt Soc Am A Opt Image Sci Vis. 2003 Dec;20(12):2228-36
references.pmid: 14686501
references.citation: Optom Vis Sci. 1994 May;71(5):323-31
references.pmid: 8065708
references.citation: Vision Res. 2003 Apr;43(9):1081-90
references.pmid: 12676249
references.citation: Invest Ophthalmol Vis Sci. 2010 Jan;51(1):614-22
references.pmid: 19684002
references.citation: Optom Vis Sci. 1999 Dec;76(12):855-60
references.pmid: 10612408
references.citation: Optom Vis Sci. 2000 Mar;77(3):140-9
references.pmid: 10772231
references.citation: Optom Vis Sci. 2009 Jun;86(6):634-9
references.pmid: 19430327
references.citation: Ophthalmic Physiol Opt. 2010 Mar;30(2):143-51
references.pmid: 20444118