title: Effect of reduced visual acuity on precision of two-dimensional tracing movements.
abstract: OBJECTIVE
  We intended to assess consequences of reduced visual acuity for performance in a natural simple motor task (tracing) using objective kinematic performance measures. Specifically, we intended to elucidate the kind of relationship between the task performance and best corrected binocular visual acuity and to determine the threshold of visual acuity when task performance starts to deteriorate.
  
  
  METHODS
  Ninety-five individuals with different best corrected visual acuity participated in the study (age 49±12 years, mean±SD, 27 men and 68 women). The participants manually traced maze-like visual patterns of different spatial complexity presented on the screen of a portable notebook computer using Clinical Kinematic Assessment Tool software. Tracing error was computed as performance measure in each trial with a spatial pattern matching technique - rigid point set registration method.
  
  
  RESULTS
  The segmented linear regression analysis showed that the relation between visual acuity and tracing errors was best described with a regression function having a break point between two data segments. Tracing performance was unaffected by values of visual acuity below 0.2 on logMAR scale, but when logMAR values increased above this critical limit (i.e. when visual acuity is further reduced), tracing errors linearly increased. The rate of the increase of the tracing error correlated with the complexity of visual stimulus shape.
  
  
  CONCLUSIONS
  Testing of fine motor functions with objective kinematic measures during visuomotor tasks may help differentiating between actual effects of reduced visual acuity on eye-hand coordination in individuals with similar levels of impairment of visual acuity.
authors.affiliation: Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies, University of Gävle, Gävle, Sweden.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Domkin
authors.affiliation: Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies, University of Gävle, Gävle, Sweden. Electronic address: hrr@hig.se.
authors.forename: Hans O
authors.initials: HO
authors.lastname: Richter
authors.affiliation: Low Vision Centre, Örebro County Council, Örebro, Sweden; Centre for Rehabilitation Research, Örebro County Council, Örebro, Sweden; School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: Christina
authors.initials: C
authors.lastname: Zetterlund
authors.affiliation: Centre for Rehabilitation Research, Örebro County Council, Örebro, Sweden; School of Health and Medical Sciences, Örebro University, Örebro, Sweden; School of Law, Psychology and Social Work, Örebro University, Örebro, Sweden.
authors.forename: Lars-Olov
authors.initials: LO
authors.lastname: Lundqvist
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D012044:Regression Analysis; D012684:Sensory Thresholds / Q000502:physiology; D013647:Task Performance and Analysis; D014786:Vision Disorders / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
keywords: Agudeza visual; Baja visión; Coordinación ojo-mano; Eye–hand coordination; Low vision; Tracing; Trazado; Visual acuity