title: Comparison of the visual function index to the Snellen Visual Acuity Test in predicting older adult self-restricted driving.
abstract: OBJECTIVE
  In this observational study, a modified version of the Visual Function Index (VF-14) and the Snellen Visual Acuity Test were compared in how well they correlated with self-restricted driving habits in older adults. The VF-14 was originally designed to assess vision in cataract patients; however, in this study, a modified version (mVF-14) was evaluated as a tool for predicting self-restricted driving in older drivers.
  
  
  METHODS
  During a 3-month period, 151 drivers over the age of 65 were screened at the local senior center. In addition to the Snellen Visual Acuity Test and mVF-14, each participant was given a questionnaire about their driving habits, previously used in self-restriction studies.
  
  
  RESULTS
  Out of 151 total participants, 134 were included and 7 nondrivers and 10 subjects who did not complete all questionnaires were excluded. One hundred one participants exhibited normal visual acuity of 20/40 or better (75%), and 110 scored over 90 on the mVF-14 (82%). Spearman's rank sum correlation coefficient was used to analyze the data and showed significant negative correlation of the mVF-14 and Snellen with self-restricted driving. Individuals with normal vision (20/40 or better on the Snellen eye test) had both high and low mVF-14 scores.
  
  
  CONCLUSIONS
  The study shows that poor vision, as indicated by the Snellen scale and low mVF-14 scores, correlates to self-imposed driving limitations. The mVF-14 showed further distinctions of self-restriction between individuals in the same Snellen Visual Acuity category. Therefore, using the mVF-14 in addition to the Snellen Visual Acuity Test can be helpful to further differentiate visual ability within older drivers who appear to have normal vision.
authors.affiliation: Department of Emergency Medicine, University of California, Irvine School of Medicine, Orange, California, USA.
authors.forename: Shahram
authors.initials: S
authors.lastname: Lotfipour
authors.forename: Bhakti Harishchandra
authors.initials: BH
authors.lastname: Patel
authors.forename: Thomas Aaron
authors.initials: TA
authors.lastname: Grotsky
authors.forename: Craig L
authors.initials: CL
authors.lastname: Anderson
authors.forename: Erin M
authors.initials: EM
authors.lastname: Carr
authors.forename: Suleman Syed
authors.initials: SS
authors.lastname: Ahmed
authors.forename: Bharath
authors.initials: B
authors.lastname: Chakravarthy
authors.forename: John Christian
authors.initials: JC
authors.lastname: Fox
authors.forename: Federico E
authors.initials: FE
authors.lastname: Vaca
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001334:Automobile Driving / Q000523:psychology*; D006801:Humans; D012647:Self-Assessment; D011795:Surveys and Questionnaires; D014787:Vision Tests / Q000379:methods*; D014792:Visual Acuity