What are the minimum vision requirements for driving?
So often we are asked “How well do you need to see to drive?” The vision rules may vary from state to state, so it is important to check the specific requirements for the state where your license was issued. The information below is an overview for Pennsylvania drivers. For complete, up-to-date information, please visit Pennsylvania Department of Transportation.
A visual acuity test is an eye exam that checks how well you see the details of a letter or symbol from a specific distance. The standard for normal vision is 20/20. If your vision is measured at 20/40 or 20/60, it means that your vision is worse than 20/20. With 20/40 vision, you need to be at a distance of 20 feet in order to see what someone with normal vision can see at 40 feet.
- In order to drive without corrective lenses, like glasses or contacts, you must have 20/70 or better vision during the day. Nighttime driving requires 20/40 or better vision.
- If you need corrective lenses to reach the vision requirements, you must wear them at all times while driving.
- If your vision can only be corrected to 20/60 you may be able to get a license that restricts you to drive during the day only.
- If your best vision is between 20/70 and 20/100, you may be eligible for a restricted license that would prohibit driving on freeways and highways.
- Restricted licensees may need to pass a vision test yearly.
Vision in One Eye Only
People who have only one eye, or have vision in only one eye have additional requirements. These requirements include 20/40 vision in the good eye. The vehicle must be equipped with mirrors or cameras that allow the driver to see 200 feet to the rear.
In order to drive, you must also meet field of vision requirements. Your horizontal visual field must be 120 degrees wide in order to qualify for a drivers license. Your visual field is measured by how well you see in your peripheral vision, while your eyes are focused forward.
If you drive professionally – like a school bus driver – the requirements are more stringent. The field of vision must be 160 degrees, and you must be able to identify colors used in traffic signals and signs: red, green and amber; and you must see 20/40 or better.
Do you have an astigmatism?
The word might sound scary, but an astigmatism is nothing to be afraid of! It is a common vision condition which most commonly occurs when the cornea (the clear front cover of the eye) is irregularly shaped.
If you have an astigmatism, the curve of your cornea is shaped more like a football, instead of round like a basketball. This irregular curvature causes vision to be blurry, because your eye cannot focus light to a single sharp point on the retina. Instead, light hits the retina in multiple places, so images are blurred.
You may have been born with astigmatism. You could have inherited it from your parents. It can decrease or increase over time. Astigmatism often occurs along with with nearsightedness, or farsightedness.
How is astigmatism measured?
Testing for astigmatism may may include:
- Visual acuity-When you read letters on a distance chart, you are measuring your visual acuity. The result is given in two numbers, like 20/40. The first number is the number of feet from the eye chart. The bottom number shows the smallest size line you can read. If you have 20/40 vision, you would have to be within 20 feet of the chart to see what someone with normal vision could see at 40 feet.
- Topography– This device measures the topography of the surface of the cornea. As you might guess, this measurement is important for a good fit for contact lenses.
- Refraction– You might know this as the “Better 1 or Better 2 test”. While you look through an instrument called a phoropter, we rotate through a series of lenses. Based on your answers, the power is then refined to determine the lenses for the clearest vision. This power can be determined with machines but patient input remains integral in determining vision needs.
How is Astigmatism Corrected?
A comprehensive eye exam will measure the correction or power needed for your vision, which may include a prescription to correct your astigmatism. Eyeglasses or contact lenses will help you to focus and to see more clearly.
- Eyeglasses. Astigmatism can be treated with a pair of prescription eyeglasses. The lens will have a prescription that compensates for the astigmatism. This prescription provides additional power in specific parts of the lens. The correction power lies along a specific axis.
- Contact lenses. Contact lenses may provide clearer vision and a wider field of view. A special toric soft contact lens offers astigmatism correction for many patients. This contact lens is weighted so that it maintains the correct axis when worn. Another contact lens option is a rigid gas-permeable (RGP or “hard”) contact lenses to help reshape the cornea decreasing the astigmatism.
- Laser and other refractive surgery procedures. LASIK or PRK surgery can correct astigmatism by reshaping the cornea. With LASIK using Custom-Vue Wavescan, your treatment is tailored to your eyes. Dr. Moran has great success treating patients with astigmatism.
Let us help you achieve your best vision. Schedule an appointment to correct your vision. Click here for more information on LASIK
Why do I see better when I look through the pinhole?
When we check your vision, we test each eye individually using an occluder.
The occluder is a simple device that covers one eye at a time. If your vision isn’t clear, we move the pinholes into place and have you look at the eye chart again. If your vision improves with the pinholes, it means that your vision may be corrected with glasses or contacts.
Occluder for eye test with no pinhole
Occluder with pinhole in place.
The pinhole is a simple way to focus light. When you look through this tiny hole, light enters through the center of the lens of the eye only. If you can read the 20/20 line when looking through the pinholes, you should be able to see 20/20 with the correct prescription. Click to learn more about 20/20 vision
Ever wonder why squinting helps you to see better? It’s the same principle as looking through the pinholes. By squinting, you reduce the focusing area, which makes things appear sharper.
If your vision does not improve when you look through the pinhole, there may be other factors that affect your vision. The other issues that could be affecting your vision may include cataracts or problems with your retina. Lack of vision improvement with this simple test can be the first step in diagnosing, and correcting your vision problems.
Corneal Topography Test
As you look into through the bright red colored rings, the topography machine creates a map of the clear front portion of your eye, the cornea. Corneal topography allows us to detect irregular conditions of the surface that can’t be measured in other ways.
How does a map of the cornea help us evaluate your vision?
A healthy cornea is very important to your vision, because 77% of the eye’s focusing ability is done by the cornea. Light enters the eye through the clear cornea. The shape and curve of the cornea plays an important role in the quality of vision. An eye with normal vision has an evenly rounded cornea, like a basketball. An eye with an astigmatism has an unevenly curved cornea, more like a football.
Corneal topography is performed by projecting lighted rings onto the surface of the eye. These rings are reflected back and measured by the instrument, and a map of the cornea is created.
Topography is an important tool in measurements for LASIK Surgery. LASIK surgical correction changes the shape of the cornea to help patients see more clearly. During LASIK, the shape of the cornea is changed to help images focus properly on the retina. Below you can see how the shape of the eye is changed with the laser after LASIK surgery. The photos show the same eye before and after LASIK.
Topography Before LASIK
Topography After LASIK
Corneal Topography is just one of the testing resources that we use when treating our patients. You can trust Moran Eye Associates to use the tools that we need to keep your eyes healthy, and your vision the best it can be. If you have questions about your vision, contact Moran Eye Associates. We focus on making vision clearer.
It’s that time of year again.
Decorative Contact Lens
Halloween is a great time to get into costume to display your alter ego or just to have some plain old scary fun. Over the last few years, decorative contact lenses have become part of these costumes. And, with familiarity comes complacency. The fact that decorative contact lenses are safe when dispensed and used properly, leads to cutting corners on their care.
Contact lenses, both the decorative type and the type that help you see, are medical devices, licensed and regulated by the FDA. They are regulated just like heart pacemakers, hip implants and other manufactured equipment used on and in the body. Selling contacts without a prescription is illegal.
Even though costume contact lenses for Halloween have no corrective vision power for nearsightedness or farsightedness, they still require a prescription from a doctor.
Dr. Moran likes to use the expression that some things are a “victim of their own success”. Since contact lenses are for the most part safe and effective, slacking in their care may allow you to “get away with it” without consequence. The problem isn’t with the lenses themselves but how they’re used. The stakes are high and cutting corners is not a risk you should take. Poor fitting lenses and improperly used lenses could lead to corneal ulcers, which could actually lead to permanent blindness.
To be safe in wearing decorative lenses you should do several things:
1. Get an eye exam.
2. Never buy contacts without a prescription.
3. Never share contact lenses.
4. Don’t sleep in your lenses.
For more information you can visit the FDA’s website regarding decorative lenses.
What is the first test we do when you come into the office for a complete vision exam?
The Autorefractor measures your prescription
We take a measurement of your vision with the AutoRefractor.
Focus on the balloon!
When you take a seat at the autorefractor, we ask you to look into the device. You will see a blurry hot air balloon at the end of a long straight road. As the balloon comes into focus, we measure your prescription.
We ask you to focus on the image (balloon) to keep your eye centered while we take measurements. It only takes just a few seconds to measure using an autorefractor. The balloon is at the center of the image, which aligns your eye perfectly for the test.
When we use this machine, nothing touches your eye, and there is no puff of air!
The autorefractor provides an objective measurement of a person’s refractive error and prescription for glasses or contact lenses. The device measures how light is changed as it enters your eye.
Better 1 or Better 2?
We don’t use the numbers from the device to order your prescription glasses or contacts. The autorefractor is just part of the process. The information from the autorefractor is used as a starting point to determine your best prescription. We take these numbers and dial them into the phoropter.
Here is where your opinion comes in. As we cycle through lenses, we ask, “Is it Better 1 or Better 2?” Your responses help us to pinpoint your best vision. When we show you different choices, we aren’t trying to trick you! We are showing you different options to find your best correction.
Why do we use a balloon photo?
The image isn’t important, but the need to focus on something at a distance is key to a good measurement. The balloon is just one of many visual targets used in the autorefractor. Besides the hot air balloon, other popular images include: a pinwheel/peppermint candy, a house (or barn) at the end of a road, a house in the middle of a field.
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