Glaucoma and fitness to drive: using binocular visual fields to predict a milestone to blindness.
OBJECTIVE
To use binocular integrated visual field (IVF) measures to predict which patients will lose visual function to a level below the legal standard for driving.


METHODS
Data from patients attending a glaucoma clinic were collected longitudinally. The time from baseline until failure to meet the criteria of the driver's license test was modeled with Cox regression. Visual field status at baseline and visual field deterioration rate at 2 years from baseline for various monocular and binocular VF indices were investigated as predictor variables. The model that provided the best fit to the data was validated using bootstrap resampling.


RESULTS
Of the patients, 20% (60/299; 95% confidence interval, 16%-25%) failed to meet the visual field criteria to prevent driver's license loss during an average follow-up of 7 years. The median age of patients was 64 years. The binocular IVF measurements gave a better fit to the observed data than the monocular measurements. Initial average visual field sensitivity and rate of visual field loss of sensitivity were significant predictors of failure to meet driver's license test criteria.


CONCLUSIONS
The IVF provides a method by which binocular visual fields can be incorporated into patient management and allows, for example, a prediction of future driver's license loss. The rate of binocular IVF sensitivity loss at 2 years of follow-up may help identify patients who could benefit from intensified intervention.
Department of Optometry and Visual Science, City University, London, United Kingdom.
Victoria M F
VM
Owen
David P
DP
Crabb
Edward T
ET
White
Ananth C
AC
Viswanathan
David F
DF
Garway-Heath
Roger A
RA
Hitchings
D001334:Automobile Driving / Q000331:legislation & jurisprudence / Q000592:standards*; D001766:Blindness / Q000175:diagnosis* / Q000503:physiopathology; D003936:Diagnosis, Computer-Assisted / Q000592:standards; D003941:Diagnostic Techniques, Ophthalmological; D004185:Disability Evaluation; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012372:ROC Curve; D011795:Surveys and Questionnaires; D006113:United Kingdom; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*