Real-world driving behaviors in individuals with homonymous visual field loss: insights from a naturalistic driving...

Drivers with homonymous visual field loss (HVFL) have complete loss of vision in one-quarter or one-half of the visual field on the same side of both eyes. Prior research investigating the effects of HVFL on driving has used self-reports, simulated driving or on-road tests in an unfamiliar vehicle. Here, for the first time, we use naturalistic driving to examine driving patterns and safety of HVFL compared to normal vision (NV) drivers in their daily driving.

Using recording devices mounted in participants' own vehicles, we monitored 16 HVFL and 16 age-matched NV drivers continuously over 1-6 months in three U.S. regions. GPS data quantified weekly driving exposure (mileage, time, and driving days), avoidance behaviors (highway, long-distance, nighttime driving), safety-related events (hard braking, acceleration, speeding), route familiarity, and time-of-day driving patterns. Self-reported exposure and avoidance were collected at baseline.

HVFL drivers showed qualitatively reduced driving exposure but similar frequencies of safety-related events and similarly high proportions of familiar road use compared to NV drivers. HVFL drivers showed a temporal shift toward earlier driving hours, reducing late afternoon and evening driving under low-light conditions. Notably, the HVFL group showed significant discrepancies between self-reported and objectively measured mileage and avoidance behaviors such as nighttime or highway driving.

Despite their visual impairment, HVFL drivers exhibited real-world driving behavior comparable to NV drivers for hard braking, acceleration and speeding, extending previous road-test findings. The observed mismatch between self-reports and objective driving metrics underscores the value of naturalistic observation and the necessity for multi-method assessment frameworks in driving evaluations.