title: Glaucoma and Driving Risk under Simulated Fog Conditions.
abstract: OBJECTIVE
  We evaluate driving risk under simulated fog conditions in glaucoma and healthy subjects.
  
  
  METHODS
  This cross-sectional study included 41 glaucoma patients and 25 age-matched healthy subjects who underwent driving simulation. Tests consisted of curve negotiation without and with fog preview at 30 m of distance and two controlled speeds (slow and fast). Inverse time-to-line crossing (invTLC) was used as metric to quantify risk; higher invTLC values indicating higher risk, as less time is available to avoid drifting out of the road. Piecewise regression models were used to investigate the relationship between differences in invTLC in fog and nonfog conditions and visual field loss.
  
  
  RESULTS
  Glaucoma patients had greater increase in driving risk under fog compared to controls, as indicated by invTLC differences (0.490 ± 0.578 s-1and 0.208 ± 0.106 s-1, respectively;P= 0.002). Mean deviation (MD) of the better eye was significantly associated with driving risk under fog, with a breakpoint of -9 dB identified by piecewise regression. For values below the breakpoint, each 1 dB lower MD of better eye was associated with 0.117 s-1higher invTLC under fast speed (adjustedR2= 57.9%;P< 0.001).
  
  
  CONCLUSIONS
  Glaucoma patients have a steeper increase in driving risk under fog conditions when compared to healthy subjects, especially when the severity of visual field damage falls below -9 dB of MD in the better eye.
  
  
  CONCLUSIONS
  By investigating the relationship between driving risk and disease severity breakpoint, this study may provide guidance to clinicians in recognizing glaucoma patients who may be unfit to drive in complex situations such as fog.
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA ; Department of Ophthalmology and Otorhinolaryngology, Federal University of Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Alberto
authors.initials: A
authors.lastname: Diniz-Filho
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Erwin R
authors.initials: ER
authors.lastname: Boer
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Elhosseiny
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Masaki
authors.initials: M
authors.lastname: Nakanishi
authors.affiliation: Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
keywords: driving; glaucoma; perimetry; visual field; visual function