Q&A for General Knowledge about Eyes
Does 20/20 mean perfect
is vision requirement for driving in California?
is the doctor looking for during an eye exam?
Does 20/20 mean perfect vision?
20/20 vision is a term used to express normal visual acuity (the
clarity or sharpness of vision) measured at a distance of 20
feet. If you have 20/20 vision, you can see clearly at 20 feet
what should normally be seen at that distance. If you have
20/100 vision, it means that you must be as close as 20 feet to
see what a person with normal vision can see at 100 feet.
20/20 does not necessarily mean perfect vision. 20/20 vision
only indicates the sharpness or clarity of vision at a distance.
There are other important vision skills, including peripheral
awareness or side vision, eye coordination, depth perception,
focusing ability and color vision that contribute to your
overall visual ability.
Some people can see well at a distance, but are unable to bring
nearer objects into focus. This condition can be caused by
hyperopia (farsightedness) or presbyopia (loss of focusing
ability). Others can see items that are close, but cannot see
those far away. This condition may be caused by myopia
comprehensive eye examination by a doctor of optometry can
diagnose those causes, if any, that are affecting your ability
to see well. In most cases, your optometrist can prescribe
glasses, contact lenses or a vision therapy program that will
help improve your vision. If the reduced vision is due to an eye
disease, the use of ocular medication or other treatment may be
What is vision requirement for driving in
The minimum licensing vision requirement for driving in
California is best corrected visual acuity(VA) to be 20/200 or
better in at least one eye, which is verified by an
optometrist(eye doctor). The DMV will not issue a driver license
and/or the driving privilege will be revoked if the minimum
requirement is not met. Presently, there is no minimum
requirement in peripheral vision. Driving restrictions may be
implemented for those drivers with best corrected visual
acuity(VA) 20/40 – 20/200 and/or loss of peripheral vision
and/or progressive eye disease affecting vision.
commercial drivers, the federal standard requires best corrected
visual acuity to be 20/40 or better.
California Vehicle Code(CVC) 12804.9 (a) (1) (E) is the
departmental authority for administering the vision exam. CVC
12805 is the authority to refuse issuance or renewal of a driver
license for not meeting minimum visual acuity licensing
standard. The DMV uses 2 methods of vision testing: Snellen
chart and Optec 1000 Vision Tester.
Snellen chart contains 5 lines of letter with decreasing letter
size at standardized 20 feet. The Optec 1000 Vision Tester uses
an instrument to simulate the Snellen chart at 26 feet.
Applicants who do not pass either exam and/or suspected vision
problems will often be referred for a vision evaluation. The
form DL62 will often need to be completed by the doctor
establishing the driver’s baseline vision and changes that can
be made to improve the driver’s vision.
3. What is the doctor looking for
during an eye exam?
Have you ever wondered what your eye doctor is actually looking
for when (s)he examines your eyes? The answer is that an eye
exam is not just a new pair of glasses or contact lenses;
because your eyes are the windows to your general health and are
valuable for disease detection and management, the doctor is
looking for any indication of significant changes in the
different parts of the eye, so that (s)he can diagnose
conditions or diseases that might require treatment.
Here’s a breakdown of the eye and how an eye doctor examines it
for conditions or diseases that might affect vision.
Eyeball: Your doctor may use one of many different tests to
measure pressure inside the eyeball. The air ‘puff test’ – an
instrument that uses a puff of air in each eye – can accurately
measure your eye pressure. Excessive pressure is often a sign of
glaucoma, which can lead to blindness. If detected early, the
condition can be managed with medications or surgery.
Cornea: Made up of clear tissue that covers the colored part of
the eye, or iris, the cornea is the eye’s outer lens. It helps
the eye to focus on distant objects. But if the cornea contains
anatomical irregularities, the result can be nearsightedness or
farsightedness. These errors can be corrected with glasses or
contact lenses. Another potential condition is corneal arcus (a
yellowish or whitish ring around the cornea), which often is an
indication of high cholesterol. If this happens your eye doctor
may suggest you to visit your primary care doctor for diagnosis
Natural Lens: As we age, the lens within each eye can become
yellow and cloudy, producing a cataract that affects vision.
Cataracts can cause your prescription to change and must be
managed until it is time to remove them through surgery.
Optic Nerve: Discoloration, depression or swelling of the optic
nerve – which connects the eye to the brain – can indicate the
presence of glaucoma, hypertension or even a brain tumor. In
many cases, therapy that includes medications and even surgery
can stabilize or improve all three conditions if diagnosis
occurs early enough.
Retina: This is the light-sensitive layer of cells inside your
eye that is crucial to vision. Your eye doctor will check the
retina carefully to see if aging has damaged the macula, a key
area of tissue. If aging has damaged has occurred, it may be the
result of age-related macular degeneration, which can cause
blindness. The condition can’t be cured, but often it can be
slowed down if diagnosed early. The key is early detection and
management by your eye doctor.
doctors also study the retina carefully for signs of prediabetes
and diabetes, looking for blood vessel leakage or hermorrhages
that could signal the presence of diabetic retinopathy. This
condition is caused by high blood-sugar levels that damage the
delicate blood vessels in the retina and, of not treated early,
can lead to severe vision loss. Diabetic retinopathy can be
managed by keeping blood sugar levels under control.