The number to the left of the forward slash (/) is the test distance. Most people are tested at 20 feet, resulting in a reading of 20/X. The number to the right of the forward slash (/) indicates how far a person with normal vision can see the object being tested. For example, if a person`s vision were determined at 20/40, it would mean that the patient could read at a test distance of 20 feet what people with normal vision could read at 40 feet. There are other methods to test the visual field. If your field of vision is 20 degrees or less, you are considered legally blind. This represents a narrow view because you will have a hard time seeing things that are not right in front of you. Sudden visual disturbances may indicate a serious eye disease that should be examined immediately. Visual acuity between 20/200 and 20/400 is classified as severe vision loss, and anything below 20/400 is considered deep vision loss. Vision tests usually involve counting fingers or special exams to determine visual acuity below 20/400 because you can`t read a standard eye chart.
You measure your eyesight by wearing glasses or contact lenses. Their vision could fall below 20/200 without them. If it improves when you put on your glasses or contact lenses, you are not considered blind under the law. It varies from person to person. You may be able to see objects from a distance, but not from the sides of your eyes (peripheral vision). Or you may have good peripheral vision but difficulty seeing objects in the distance. The vision of a person who is legally blind is at least 10 times worse than that of a person with normal vision. Being legally blind affects your eyesight, but that doesn`t have to stop you from living a fulfilling life.
In most states, drivers must have 20/40 vision or better for an unrestricted driver`s license. If you wear glasses or contact lenses, your corrected vision should be at least 20/40. A special eye chart is needed to determine your exact visual acuity if it is less than 20/200. A special eyetable can also give you more accurate results between 20/100 and 20/200. Total blindness is the complete absence of light perception and shape perception and is recorded as “NLP”, an abbreviation for “no light perception”. Cataracts are the exception because vision can be restored by surgery to remove the clouded lens and, in most cases, replace it with an implant. According to the American Foundation for the Blind, legally blind is not the same as completely blind, which is used to describe the inability to see anything with both eyes. Most people who are legally blind have some eyesight.
These terms describe the ability to perceive the difference between light and dark or daylight and night. A person may have severely impaired vision and still be able to determine the difference between light and dark, or the general source and direction of a light. “Legally blind” is the definition of blindness used by the United States Social Security Administration (SSA) to determine whether a person is eligible for disability benefits, tax exemptions, and training for the visually impaired. An ophthalmologist will measure visual acuity and visual field to determine if a person is legally blind. It is often mistakenly assumed that a blind person cannot see anything at all; However, this is not the case. Visual impairment or visual acuity of 20/100 or worse can affect your functional vision and cause difficulty seeing things from a distance. This often requires you to use alternative methods to perform daily tasks. In the United States, the definition of blindness under the law is twofold. The first part concerns visual acuity. This is based on a standard eye test with an eye chart such as the Snellen Eye Chart.
People often ask about the difference between being blind and being “legally blind.” Because “blindness” can mean many different things, blindness under the law is the threshold at which a person is considered visually impaired for legal purposes, such as insurance purposes, to receive certain benefits, or to be accepted into various programs. The second part of the term blindness is based on your field of vision, which is how you can see to the side without moving your eyes. Visual acuity eye maps test your central vision. Treatments for legal blindness vary depending on the cause and stage of the disease. Age-related eye conditions are usually prescription medications or eye procedures aimed at delaying or preventing vision from getting worse. The government uses the term “statutory blindness” to decide who can receive certain benefits, such as disability or vocational training. This is not the same as being completely blind. The severity of visual impairment may be categorized differently for certain purposes. For example, in the United States, we use the term “legal blindness” to indicate that a person is eligible for certain educational or federal programs. Blindness is defined as visual acuity of 20/200 or worse, with the best possible correction, or a field of view of 20 degrees or less.
Eye trauma or injury and genetic diseases, such as Usher syndrome, can also lead to legal blindness. Normal visual acuity is considered 20/20 vision, which corresponds to line 8 on the Snellen Eye chart. This means that you can clearly read this line from 20 feet away without correction. If you can read line 8 (D E F P O T E C) at a distance of 20 feet while wearing your usual glasses or contact lenses, the doctor will record your vision (or visual acuity) as 20/20 with the best correction. No eye prescription should be considered “bad”. Different prescriptions refer to different levels of correction needed to restore normal vision. Here is a definition of low vision that refers to visual acuity: Steinkuller P. Legal Vision Requirements for Drivers in the United States.
WADA Journal of Ethics. 2010;12(12):938-940. doi:10.1001/virtualmentor.2010.12.12.hlaw1-1012. Like visual impairment, there are many different definitions of visual impairment. “Visual impairment” is a broad term that describes a wide range of visual functions, from visual impairment to complete blindness. Visual acuity is a number that indicates the sharpness or clarity of vision. A visual acuity measurement of 20/70 means that a person with 20/70 vision who is 20 feet away from an eye map sees what a person with intact vision (or 20/20) can see from 70 feet away. You may be surprised to learn that it is Uncle Sam, not the doctor, who determines whether you are legally blind.
If you are completely blind, you cannot see any light or shape. Among people with eye diseases, only about 15% can see nothing at all. If you are legally blind, you can still see, but not so clearly. In the United States, a person is legally blind if: Your doctor will check your vision during a standard eye exam. Striem-Amit E, Gen M, Amedi A. “Visual acuity of congenital blind persons by visual sensory substitution for auditory. PLoS One. 2012;7(3):e33136. doi:10.1371/journal.pone.0033136 Visual impairment is a visual acuity of 20/40 or worse when wearing corrective lenses. The first row of Snellen`s eyetable is for 20/200 vision, while line 2 is for 20/100 visual acuity.
This means that you have to be 20 feet away to see something as clearly as a person with normal vision can see with the same clarity from 100 feet away. AMD is a condition that affects the macular region of the retina. It is one of the leading causes of blindness in adults over the age of 65. On an eye prescription, 0.00 represents vision that does not require correction. The numbers indicate the severity of your myopia or farsightedness. The further away from zero (+ or -), the worse the vision. The reason some people use this term is because there are many different types of “blindness.” People mistakenly believe that all blind people see only darkness or literally nothing at all. In fact, blindness may involve seeing colors or light, or having greater visual acuity in some parts of their field of vision, while others are blurred or absent. Visual acuity of 20/20 is considered “perfect vision” because no help is needed to see better, and the average person with good vision can clearly see what doctors have determined to be 20/20 vision.
Some people (especially young people with good eyes) may see letters smaller than the overall size “20/20”. Valenzuela T, Mosier J, Sakles J. Tunnelblick. YWAM 2013;38(1):32-4, 36-7.