Visual Function and Driving Performance Under Different Lighting Conditions in Older Drivers: Preliminary Results From an Observational Study

Assessment of visual function under various lighting conditions in a cohort of active older drivers: dimensionality and principal metrics

Purpose

While traditional driving ability evaluations typically assess visual acuity (VA) under photopic conditions, visual functions other than photopic VA also play a crucial role in driving. For older individuals, age-related vision change can impact driving abilities, particularly under mesopic lighting conditions with glare during nighttime driving. This study aims to investigate how visual functions vary across different lighting conditions, examine their correlations, and identify the principal visual function metrics that enable a more comprehensive assessment of active older drivers.

Methods

Twenty active older drivers (aged 63 to 87 years; mean = 70 years) participated. All possessed valid driver's licenses, drove at least once per week, and did not use any low vision aids for driving. Six participants had undergone cataract surgery. Participants completed a battery of visual tasks with their habitual correction for daily driving. VA, contrast sensitivity function (CSF) and visual field map (VFM) were measured under photopic and mesopic conditions using the qVA, qCSF and qVFM procedures. Additionally, VA and CSF were assessed in the presence of glare under mesopic condition. Correlations and principal component analysis (PCA) were conducted to identify principal visual function metrics.

Results

VA and CSF exhibited variation across lighting conditions (ps < 0.005), with significant correlations observed between multiple pairs of visual functions. A trend of stronger correlations was found in participants who had undergone cataract surgery. PCA suggested that four metrics are necessary to explain most of the nonrandom variation in the data. Mesopic VA was the most informative measure, accounting for 47% of the total variance. Adding a measure of VFM increased the explained variance to 70%. To explain approximate 80% of the total variation, three measures were required, while four measures were needed to achieve 90%.

Conclusion

Using a PCA-based selection approach, the minimal set of visual function metrics for evaluating visual function in active older drivers was identified. These findings provide valuable insights for establishing optimal clinical outcome measures for this population.

Diurnal variation of visual functions for driving with and without orthokeratology: A multicenter study

PURPOSE

To investigate orthokeratology-related diurnal variations in visual acuity, contrast sensitivity, mesopic (twilight) vision, and glare sensitivity, and to verify compliance with requirements for driver licensing.

METHODS

In this prospective, multicenter, controlled study, fifty myopic (range, -1.00 to -4.50 D) and non-presbyopic glasses or soft contact lens wearers (age range, 16-39 years) were fitted with orthokeratology (OK) contact lenses. Before and after completion of OK lens fitting, measurements of visual acuity, contrast sensitivity, mesopic vision and glare sensitivity were performed at three times of the day, morning, afternoon and evening using a standardized binocular vision testing device (Oculus Binoptometer 4P). Monocular and binocular visual acuity were tested according to ISO 8596 and compared to requirements of cars and motorcycles drivers in different countries.

RESULTS

Compared to the prior correction, binocular visual acuity (logMAR) with orthokeratology was statistically significant better in the morning (0.04 ± 0.12; p < 0.05) and afternoon (0.04 ± 0.10; p < 0.05), while the difference was not statistically significant in the evening (p = 0.512). Furthermore, there was no statistically significant difference in contrast sensitivity in the morning (p = 0.813), afternoon (p = 0.742) or evening (p = 0.945). For both mesopic vision and glare sensitivity, there was no statistically significant difference between the contrast levels achieved with orthokeratology compared to the prior correction in the morning (p = 0.083; p = 1.000), afternoon (p = 0.054; p = 0.125) or evening (p = 0.195; p = 0.635). With orthokeratology, no statistically significant diurnal variation was found for binocular visual acuity, contrast sensitivity, mesopic vision or glare sensitivity (p > 0.05).

CONCLUSIONS

These results provide evidence, that visual functions of OK lens wearers are stable throughout the day and comparable to the prior correction. Although the visual standards for driving are not uniform within countries, the requirements for visual acuity are met in all of the countries. Mesopic vision and glare sensitivity, which are suggested as other aspects to influence driving performance, also appear to be constant over the course of the day.