Intraocular scattering as a predictor of driving performance in older adults with cataracts

Abstract

Cataracts can limit a person's ability to perform vision-dependent tasks safely, affecting the quality of life of older people. This study examines the relationship between visual function and driving, by studying which visual parameters might be important for predicting driving performance in older drivers with and without cataracts, ascertaining whether the objective measurement of intraocular scattering should be considered in assessment procedures for older drivers. This cross-sectional study involved a total of 20 older drivers (10 patients with bilateral cataracts and 10 control subjects). All participants were examined for visual acuity, contrast sensitivity, visual discrimination capacity, and intraocular scattering. Driving performance was also tested using a driving simulator. To study the relationship between visual parameters and driving performance, a correlation analysis and regression model were used. Drivers with cataracts showed a significantly impaired (p<0.05) visual function, with an Objective Scattering Index (OSI) 3.5 times greater than the control group. Driving performance was also significantly worse (p<0.05) in drivers with cataracts, reflected by a notable deterioration in lane keeping. The correlation analysis showed significant associations between driving performance and all the visual parameters studied. Finally, the regression model revealed that the OSI was the best predictor of driving performance, accounting for 51.3% of its variance. Visual function and driving performance are markedly deteriorated when cataracts are present. Our results demonstrate that the objective scattering index (OSI) has a high predictive power when it comes to simulated driving performance in older drivers, both with and without cataracts, suggesting that scatter measurements could be important in helping better understand visual limitations in older drivers.

Impact of Age-Related Vision Changes on Driving

“…Moreover, it is worth noting that the effects of straylight during nighttime driving could complicate driving for older drivers with no eye disease, even in low-beam glare conditions [ 20 ]. Our results are consistent with those of previous studies [ 17 , 20 , 28 ] and suggest that intraocular straylight could be a particularly useful visual parameter to measure when assessing the fitness to drive of older drivers, although this conjecture requires further research.…”

“…Older drivers usually reduce their speed to mitigate the perceived risk due to either the environment or their visual, cognitive, or motor decline [ 35 ]. Nevertheless, according to our results, it has been suggested that reducing driving speed is not enough to eliminate any errors in road sign recognition and hazard avoidance [ 14 ], nor does it improve performance in terms of driving measures (e.g., driving outside the lane) in older drivers with eye disease [ 28 ] or when distracted [ 27 ].…”

“…With respect to sign legibility, Dewar et al [ 39 ] noted that only older drivers presented a reduced legibility distance in the presence of glare. In one of our recent studies concerning older drivers with and without cataracts, we found significant correlations between greater halo perception and increased difficulty maintaining the car within the lane and a worse general driving performance [ 28 ]. Similarly, in this study, we found that drivers with poorer visual discrimination perform worse in the driving simulator, particularly in terms of lane stability.…”

“…All participants drove in a scenario with identical traffic flow and the same number of peripheral events as above. More information on this simulated environment can be found elsewhere [ 27 , 28 ]. Participants received at least two training sessions separated by a seven-day washout period.…”

“…We considered the following individual variables when calculating the ODPS: distance travelled while encroaching the hard shoulder, SD of the steering wheel angular velocity, SDLP, total distance driven outside the driver’s lane, and total time. We did not include the mean speed because we considered that it is not indicative of driving performance quality, in line with other studies [ 28 , 30 , 31 ]. For the mountain road section, we ignored the distances travelled while encroaching the opposite lane and the hard shoulder because these distances are accounted for in the total distance driven outside the driver’s lane.…”