Vision and Driving
Good vision is vital for safe driving so you can read road signs and markings, identify signals and observe hazards. A driver with impaired vision is potentially hazardous on the road. Drivers with vision loss may not be aware of the loss or how it can affect driving.
Why is vision screening part of an OT Driving Assessment?
Vision is a critical component of driving for all drivers. A comprehensive medico-legal assessment must always address vision in driving. Not everyone will require a vision assessment by a specialist. (This is not practical). The occupational therapist conducts a screen of your vision in the driving assessment to identify if further testing by a specialist in vision is required. If you have a vision deficit the occupational therapist is likely to ask for a vision report from a vision specialist.
What is assessed in an OT vision screen?
The following three areas are important to consider for safe driving;
- Visual Acuity (The ability to discriminate details of an image)
- Fields of Vision (The area over which an individual can see)
- Eye movement / coordination (The ability of the eye to look at / track objects in a coordinated way)
Visual acuity is assessed by asking you to read the smallest line on an eye chart at a distance of 6 meters. Legal acuity for driving is 6/12. If you need to wear glasses or contact lenses to achieve this, an 'S' endorsement will be added to your license and you must drive with glasses or contacts at all times.
Visual Field Loss
People often adapt quickly to visual field loss and may not be aware of the loss or may report only noticing it in one eye. People with visual field loss often report no concerns about their driving but they can be unsafe.
The RTA Medical guidelines 'Assessing Fitness to Drive, Commercial and Private Vehicle Drivers' (2012) are used to determine if a driver's visual fields are within RMS standards. These guidelines stated that field measurements must be; 120 degrees across the horizontal meridian and 10 degrees above and below the horizontal meridian for legal driving. If you have been diagnoses with a visual field loss a medical report from a vision specialist will be required prior to your driving assessment. 'Confrontation Testing' is the method of visual field testing conducted by the OT for all other drivers.
Conditions for retaining a license are not met for someone with a hemianopia (loss of half of the field of vision in one or both eyes). Once the RMS is notified of this condition the driver's license will be cancelled. It is possible to continue driving with some visual field loss; eg. small scotomas (blind spots) and quadrantanopia (loss of a quarter of the field), however, an Occupational Therapy Driving Assessment will be required to determine fitness.
Deficits in eye movements may result in double vision, blurred vision, over shooting or difficulty tracking objects. These difficulties may all affect driving safety. Fast and slow eye movements will therefore be tested in the screen.
How do I know if I meet the vision standards?
Rehab on Road aims to support the standards listed in 'Assessing Fitness to Drive'. You can view these standards via the following link; https://www.onlinepublications.austroads.com.au/items/AP-G56-12
If you have been diagnosed with a vision deficit we will usually require a report from a vision specialist to determine if your vision meets RMS guidelines for safe driving. If you are outside the standards it is sometimes still possible to continue driving once you have demonstrated fitness via an occupational therapy driving assessment. The RMS may require medical information (eg. as in the case of visual field loss) before an on road assessment is approved.
Is there help available to enable me to drive with a vision deficit?
It is possible to correct or compensate for some vision conditions to allow safe and legal driving for some people. Rehab on Road works with Orthoptists and Behavioural Optometrists for vision conditions such as double vision and monocular vision. Eye patches and prisms can be prescribed by vision specialists to correct some conditions. Mirror modifications can be added to the vehicle to compensate for vision loss and driving techniques can be taught as compensation strategies.
An occupational therapy driving assessment will help your doctors and the RMS confirm you are safe to continue driving (where possible).