Central vision
– the five-degree cone that makes up only three percent of a driver's total visual field. It provides detail of objects and conditions and is the primary visual function employed in targeting. Direct your central vision to your target area and front zones.
What is the person's outermost vision?
Vision –
The cornea
acts as the eye's outermost lens. It functions like a window that controls and focuses the entry of light into the eye.
What is focal vision driving?
The vision that identifies specific objects. What is focal vision?
Assesses depth, position, and movement in an area and point in time
. What does central vision do? The area or edge around focal and central vision areas.
What is a IPDE?
We use the IPDE (
Identify, Predict, Decide, Execute
) approach to driving to deal with potential and real hazards.
What are the three 3 fields of vision?
Our central vision covers about three degrees of our visual field
and peripheral vision
, or side vision, covers the rest. The three degrees of central vision is a very small area in your total field of vision.
When driving you should keep your eyes in a fixed stare?
You
should shift your eyes every two or three seconds
to avoid the fixed stare—a steady gaze along one line of sight. Moving your eyes keeps you alert and gives you a constant update of what is in or about to enter the traffic pattern.
Which vision is first affected by drugs?
Peripheral vision
is strongly affected by fatigue, drugs, and speed of travel. It often gives the driver an initial warning of a changing or closed space area. A novice driver will need to develop a visual lead in order to keep steering reversals to a minimum.
What are the three types of vision loss?
- Blurred vision (called refractive errors)
- Age-related macular degeneration.
- Glaucoma.
- Cataract.
- Diabetic retinopathy.
What is the vision limit for driving?
Car drivers must have visual acuity measured at
6/12 or above
. That means that in an eye test, you must be able to read the fifth line from the bottom of the chart.
What causes central vision loss?
Central vision loss can occur when a person suffers from
age-related macular degeneration and/or diabetic retinopathy
. It starts with a small dark spot in the centre of the vision that gets larger over time. Central vision loss can progress very quickly.
What must a driver do to identify?
- I—Identify—Locate potential hazards within the driving scene. …
- P—Predict—Judge where the possible points of conflict may occur. …
- D—Decide—Determine what action to take, when, and where to take it. …
- E—Execute—Act by maneuvering the car to avoid conflicts.
What are the four steps in the IPDE process?
- I—Identify—Locate potential hazards within the driving scene.
- P—Predict—Judge where the possible points of conflict may occur.
- D—Decide—Determine what action to take, when, and where to take it.
- E—Execute—Act by maneuvering the car to avoid conflicts.
How many blocks is 15 seconds?
In the city, 10 to 15 seconds is about
one block
. When you drive in city traffic, you should look at least one block ahead. On the highway, 10 to 15 seconds is about a quarter of a mile.
What is a good field of vision?
A normal visual field is an
island of vision measuring 90 degrees temporally to central Fixation, 50 degrees superiorly and nasally, and 60 degrees inferiorly
. Visual acuity increases from movement discrimination in the extreme peripheral vision to better than 20/20 in the center of vision.
What does an abnormal visual field test mean?
A test that shows
visual field loss
means that vision in some areas is not as sensitive as normal. It could be just a little vision lost in a small area, or all vision lost in large areas. The amount of vision lost and the areas affected are measured by the visual field test.
Can you drive with visual field loss?
Clearly
if there is significant visual field loss, then it is unsafe to drive
but if the loss is borderline by the DVLA standards, then it is important to be aware that you do not simply give up.
