The longitudinal relationship between rates of progressive retinal nerve fiber layer (RNFL) loss and driving performance in glaucoma.

Abstract

Purpose : Inability to drive is a major concern for patients with glaucoma. The purpose of this study was to examine the longitudinal relationship between rate of change in RNFL thickness and change in ability to divide attention during a simulated driving task.

Methods : 152 glaucoma patients were followed for an average of 3.7 years. At each visit investigations included visual acuity, contrast sensitivity, perimetry and optical coherence tomography (OCT). Ability to divide attention was assessed using a driving simulator to measure reaction times to stimuli presented simultaneously during two central tasks 1) curve negotiation and 2) car following. A joint longitudinal multivariate mixed model was used to investigate the association between rates of change in driving performance and RNFL thickness over time. Reaction time values were positively skewed therefore natural logarithms were calculated. The effect of potentially confounding variables including integrated binocular visual field (BVF), age, gender, race, and Montreal Cognitive Assessment score was also investigated.

Results : Average age at baseline was 64.8 ± 11.2 years. RNFL thickness in better and worst eyes was 84.8 ± 15.1 μm and 76.8 ± 16.7 μm respectively. The average rate of better eye RNFL loss was 0.4 ± 0.5 μm/year. Progressive RNFL loss was associated with increased reaction time to the curve negotiation divided attention task. Each 1μm/year faster loss was associated with a 0.02 ln unit/year increase in reaction time (R² = 10.9%, P < 0.001) (Figure 1). In a multivariable model, accounting for change in BVF sensitivity over time, visual acuity, contrast sensitivity, age, gender and cognitive ability, each 1μm/year faster RNFL loss was associated with a 0.02 ln unit/year increase in reaction time (R² = 40.1%, P < 0.001). Similar results were found for the car following divided attention task. Each 1μm/year faster loss was associated with a 0.09 ln unit/year increase in reaction time (R² = 29.4%, P < 0.001).

Conclusions : Faster rates of glaucomatous RNFL loss were associated with worse simulated driving performance over time, with RNFL measurements providing additional information to BVF sensitivity. Inclusion of structural measurements may improve the ability to determine which patients with glaucoma are likely to develop impaired ability to perform tasks requiring divided attention.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.