Abstract
Purpose: :
Human immunodeficiency virus infection is associated with visual dysfunction that we have shown is at least in part due to retinal damage even in the absence of infectious retinitis. Based on our previous research and that of others, low CD4 nadir (below 100 at some point) HIV patients have decreased visual function when compared to high CD4 nadir HIV positive patients and HIV negative patients. This study wished to determine whether the reported decrease in visual function of low CD4 HIV positive patients is severe enough to impair their driving ability.
Methods: :
Twenty two HIV positive patients without retinitis, 10 with low CD4 nadir (<100) and 12 with high CD4 (>200) performed a simulation driving test on the STISIM driving simulator (Systems Technology Inc., Hawthorne, CA). 16 normal HIV negative subjects performed the same driving simulation to serve as controls. During the driving simulation, occurrence of driving mistakes such as collisions, off road accidents, and speed exceedences were recorded. ANOVA was then utilized to examine the number of mistakes made across the low CD4, high CD4, and control groups.
Results: :
After performing adjustments for age and gender, low CD4 patients had significantly more collisions (average of 3.2 for low CD4 patients vs. average of 1.8 for controls, p=0.021) than control drivers without HIV. Both high CD4 and low CD4 patients also hit more pedestrians than control patients (average of 1.36 (low CD4) and average of 1.57(high CD4) compared to average of 0.84 pedestrians hit in the control group, p=0.046). Low CD4 and high CD4 patients also engaged in more off road excursions than controls (averaging 11.2 excursions for Low CD4 vs. 6.4 for High CD4 and 4.6 for controls, p=0.00325). Speeding tickets received and speed excesses made both showed a trend of being higher in low CD4 patients than in high CD4 and control patients(p=0.1 and p=0.15).
Conclusions: :
HIV patients with a prior low CD4 nadir may have impaired driving ability, which may impair their personal safety as well that of other drivers. This is due in part to retinal function and structural defects. In addition to the potential public health problems associated with this dysfunction, this suggests that the visual dysfunciton in HIV patients shown by tests of color vision, perimetry and contrast sensitivity as well as electroretinography have correlates in real world tests of vision function such as driving.
Keywords: AIDS/HIV • visual impairment: neuro-ophthalmological disease • retina