Ms. Carrie Huisingh, doctoral student in the department of epidemiology and statistician in the department of ophthalmology, and Dr. Gerald McGwin, Jr., professor and vice chair in the department of epidemiology, at the University of Alabama at Birmingham, recently conducted a study to evaluate the association between the binocular visual field defects in drivers with glaucoma and the risk of motor vehicle collision (MVC) involvement. UAB co-investigators include Dr. Cynthia Owsley, professor, and Dr. Christopher A. Girkin, professor and chair, in the department of ophthalmology.
A retrospective cohort study was conducted on 438 drivers with glaucoma, ages 55 years or older, using data from 1994 through 2000. Demographic, clinical, and driving characteristics were obtained from chart abstractions and patient survey. Binocular field measures were generated by combining data from the monocular (central 24-degree radius) fields whereby the binocular field measure was defined as the more sensitive point at each monocular field location. Measures included threshold (TH), total deviation (TD), and pattern deviation (PD); severe impairment in these measures was defined as falling into the worst quartile. MVC data were obtained from police records. Rate ratios (RR) and 95 percent confidence intervals (CI) were calculated.
Results of the study indicate that drivers with severely impaired PD measures were twice as likely to have an at-fault MVC compared with those not severely impaired (RR, 2.13; 95 percent CI, 1.21-3.75); those with severely impaired TH (RR, 1.49; 95 percent CI, 0.81-2.74) and TD (RR, 1.50; 95 percent CI, 0.82-2.74) also had an increased rate of at-fault MVCs, although these were not significant. When the binocular central visual field was stratified into nine regions, drivers with impaired TH, TD, or PD had similarly elevated MVC rates in all regions compared with those not severely impaired, although not all reached statistical significance.
On the basis of clinical measures of visual field routinely used in the management of glaucoma, the researchers concluded that drivers with glaucoma with severe PD field defects in the binocular field have a higher rate of at-fault MVC compared with those with less impaired or unimpaired binocular visual fields.
“Binocular Visual Field Impairment in Glaucoma and At-fault Motor Vehicle Collisions” was published in February 2015 in the Journal of Glaucoma.