Driving with homonymous visual field loss: a review of the literature

Abstract

Driving is an important rehabilitation goal for patients with homonymous field defects (HFDs); however, whether or not people with HFDs should be permitted to drive is not clear. Over the last 15 years there has been a marked increase in the number of studies evaluating the effects of HFDs on driving performance. This review of the literature provides a much-needed summary for practitioners and researchers, addressing the following topics: regulations pertaining to driving with HFDs, self-reported driving difficulties, pass rates in on-road tests, the effects of HFDs on lane position and steering stability, the effects of HFDs on scanning and detection of potential hazards, screening for potential fitness to drive, evaluating practical fitness to drive, and the efficacy of interventions to improve driving of persons with HFDs. Although there is clear evidence from on-road studies that some people with HFDs may be rated as safe to drive, others are reported to have significant deficits in skills important for safe driving including taking a lane position too close to one side of the travel lane, unstable steering and inadequate viewing (scanning) behaviors. Driving simulator studies have provided strong evidence of a wide range in compensatory scanning abilities and detection performance, despite similar amounts of visual field loss. Conventional measurements of visual field extent (in which eye movements are not permitted) do not measure such compensatory abilities and are not predictive of on-road driving performance; thus, there is a need to develop better tests to screen for visual fitness to drive of people with HFDs. We are not yet at a point where we can predict which HFD patient is likely to be a safe driver. Therefore, it seems only fair to provide an opportunity for individualized assessments of practical fitness to drive either on the road and/or in a driving simulator.

The importance of reaction time, cognition, and meta-cognition abilities for drivers with visual deficits

“…The results obtained in this study reveal that the validity of these tests is at least questionable. The conclusion Bowers (2016) expresses in her review on homonymous VFL still holds, according to the results obtained in this study: "Therefore, it seems only fair to provide an opportunity for individualized assessments of practical fitness to drive either on the road and/or in a driving simulator." The implication of these findings is that individuals with VFL need to be assessed and their driving skills tested.…”

Fahreignung aus (neuro)ophthalmologischer Sicht

“…In den USA haben sich mehrere Arbeitsgruppen über viele Jahre sehr intensiv mit der Frage der Fahrtauglichkeit bei Sehbehinderung befasst [21,23]. In einer umfassenden Übersicht stellt Bowers deutlich dar, dass die augenärztliche Untersuchung der Gesichtsfelder kein geeignetes Instrument zur Bestimmung der Fahrtauglichkeit sei, da Kompensationsmechanismen nicht erfasst werden und es eindeutig Personen gäbe, die trotz ausgedehnter Gesichtsfeldausfälle ausreichend sicher ein Kfz führen könnten [23]. Die Beurteilung allein an einem Fahrsimulator erscheint hierbei dennoch nicht ausreichend, weswegen grundsätzlich eine Prüfung im realen Straßenverkehr zu bevorzugen ist [21,23].…”

“…In einer umfassenden Übersicht stellt Bowers deutlich dar, dass die augenärztliche Untersuchung der Gesichtsfelder kein geeignetes Instrument zur Bestimmung der Fahrtauglichkeit sei, da Kompensationsmechanismen nicht erfasst werden und es eindeutig Personen gäbe, die trotz ausgedehnter Gesichtsfeldausfälle ausreichend sicher ein Kfz führen könnten [23]. Die Beurteilung allein an einem Fahrsimulator erscheint hierbei dennoch nicht ausreichend, weswegen grundsätzlich eine Prüfung im realen Straßenverkehr zu bevorzugen ist [21,23]. Dennoch ist zunächst wesentlich, die vorliegenden Einschränkungen des Sehvermögens genau zu kennen, aufgrund der gesetzlichen Vorgaben ist daher eine Gesichtsfelduntersuchung unerlässlich.…”

Vision and driving: a look at the research road ahead

“…Several papers focus on the question of the role of visual field defects on driving, a topic that has challenged researchers over many decades. Papers include literature reviews on the link between various ocular diseases and driving, including those resulting in visual field loss, while another review focuses specifically on the effects of homonymous visual field loss on various driving outcome measures . These reviews highlight the range of research undertaken in this area but underscore the urgent need for high quality research to support evidence‐based decisions about driving safety in those with visual impairment, particularly those with visual field loss.…”

“…Papers include literature reviews on the link between various ocular diseases and driving, including those resulting in visual field loss, 2 while another review focuses specifically on the effects of homonymous visual field loss on various driving outcome measures. 3 These reviews highlight the range of research undertaken in this area but underscore the urgent need for high quality research to support evidence-based decisions about driving safety in those with visual impairment, particularly those with visual field loss. Research papers on the effects of simulated field loss on hazard perception 4 and true visual field loss on vehicle control in a driving simulator 5 demonstrate the complexity of the effects of field loss on driving-related outcomes and highlight the problems in making licensing decisions for drivers with field loss as reported in another study.…”