Impact of Oncoming Headlight Glare With Cataracts: A Pilot Study

Abstract

Purpose: Oncoming headlight glare (HLG) reduces the visibility of objects on the road and may affect the safety of nighttime driving. With cataracts, the impact of oncoming HLG is expected to be more severe. We used our custom HLG simulator in a driving simulator to measure the impact of HLG on pedestrian detection by normal vision subjects with simulated mild cataracts and by patients with real cataracts.Methods: Five normal vision subjects drove nighttime scenarios under two HLG conditions (with and without HLG: HLGY and HLGN, respectively), and three vision conditions (with plano lens, simulated mild cataract, and optically blurred clip-on). Mild cataract was simulated by applying a 0.8 Bangerter diffusion foil to clip-on plano lenses. The visual acuity with the optically blurred lenses was individually chosen to match the visual acuity with the simulated cataract clip-ons under HLGN. Each nighttime driving scenario contains 24 pedestrian encounters, encompassing four pedestrian types; walking along the left side of the road, walking along the right side of the road, crossing the road from left to right, and crossing the road from right to left. Pedestrian detection performances of five patients with mild real cataracts were measured using the same setup. The cataract patients were tested only in HLGY and HLGN conditions. Participants’ visual acuity and contrast sensitivity were also measured in the simulator with and without stationary HLG.Results: For normal vision subjects, both the presence of oncoming HLG and wearing the simulated cataract clip-on reduced pedestrian detection performance. The subjects performed worst in events where the pedestrian crossed from the left, followed by events where the pedestrian crossed from the right. Significant interactions between HLG condition and other factors were also found: (1) the impact of oncoming HLG with the simulated cataract clip-on was larger than with the plano lens clip-on, (2) the impact of oncoming HLG was larger with the optically blurred clip-on than with the plano lens clip-on, but smaller than with the simulated cataract clip-on, and (3) the impact was larger for the pedestrians that crossed from the left than those that crossed from the right, and for the pedestrians walking along the left side of the road than walking along the right side of the road, suggesting that the pedestrian proximity to the glare source contributed to the performance reduction. Under HLGN, almost no pedestrians were missed with the plano lens or the simulated cataract clip-on (0 and 0.5%, respectively), but under HLGY, the rate of pedestrian misses increased to 0.5 and 6%, respectively. With the optically blurred clip-on, the percent of missed pedestrians under HLGN and HLGY did not change much (5% and 6%, respectively). Untimely response rate increased under HLGY with the plano lens and simulated cataract clip-ons, but the increase with the simulated cataract clip-on was significantly larger than with the plano lens clip-on. The contrast sensitivity with the simulated cata...

Nighttime driving: visual, lighting and visibility challenges

“…The negative impacts of simulated cataracts were shown to be greater than for optical blur, even when visual acuity was reduced by the same amount, which is likely to have resulted from the reductions in contrast sensitivity and increased light scatter associated with the simulated cataracts . These findings were supported by a nighttime driving simulator study which used a similar experimental paradigm and incorporated bright LED lights to simulate the effects of oncoming glare, demonstrating that the detrimental effects of simulated cataracts on nighttime pedestrian detection were exacerbated by glare …”

Comparison of Pedestrian Detection With and Without Yellow-Lens Glasses During Simulated Night Driving With and Without Headlight Glare

“…Further details of the scenario design can be found in a previous report. 14 With yellow filters, the dark navy blue shirt and blue jeans may be less visible to drivers, forcing them to rely on other parts of the pedestrian (eg, face, hands). To control for this possibility, 6 additional younger individuals completed the same 8 drives; however, the pedestrian wore an orange shirt.…”

“…Four older participants' detection of pedestrians wearing the orange shirt was also measured. Older individuals are more likely to be users of night-driving glasses because they report night-driving difficulties with oncoming car's HLG owing to incipient cataracts 14 or other age-related eye diseases and may be searching for a method to improve their night-driving comfort and safety.…”

Impact of Headlight Glare on Pedestrian Detection with Unilateral Cataract

“…The scenarios use a custom HLG simulator that presents light (using light emitting diodes and a beam splitter) that is similar to those from the headlamps of an oncoming car at night. These scenarios were used in a pilot study on the impact of HLG with real and simulated bilateral cataracts and are described in detail in Hwang et al (2018).…”

“…In a previous study, we used a custom headlight glare (HLG) simulator integrated with a driving simulator to measure pedestrian detection performance with and without dynamic HLG in nighttime driving scenarios (Hwang et al, 2018). Participants with mild cataract simulation (0.8 Bangerter foils were used bilaterally to reduce visual acuity to ~20/35 and contrast sensitivity to ~1.4 LogCS) missed 6% of the pedestrians that walked along either side or crossed the road in either direction in the presence of oncoming HLG, compared to 0.5% without the simulated cataract.…”