A person is considered legally blind if they cannot see at six metres what someone with normal vision can see at 60 metres or if their field of vision is less than 20 degrees in diameter.
While there's no "bad" eye prescription, you can be "legally blind" when your prescription is 20/200 or worse. Different diseases can cause bad eyesight, some treatments can help improve your vision.
Legal blindness is defined as: 20/200 or worse vision in the better seeing eye, or less than 20° of a field of vision.
If you're legally blind, your vision is 20/200 or less in your better eye or your field of vision is less than 20 degrees.
A lens Rx for -14 Diopters tells us you have a very, very high degree of nearsightedness (myopia). This would be considered in the "severe" range. Of all the people who are myopic, less than 2% are worse than -10 Diopters.
If your number is between -0.25 and -2.00, you have mild nearsightedness. If your number is between -2.25 and -5.00, you have moderate nearsightedness. If your number is lower than -5.00, you have high nearsightedness.
In North America and most of Europe, legal blindness is defined as visual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible.
The maximum negative eye power is typically around -20 diopters.
-3.00 diopters or less is mild. -3.00 to -6.00 diopters is moderate. -6.00 to -9.00 diopters is severe.
First: What does it mean to be "legally blind?" In most states, if you have distance visual acuity less than 20/200 that is not correctable with glasses/contact lenses, you are legally considered to be "severely visually handicapped" (which used to be called "legally blind").
At values +0,25 to +3,0 diopters we speak about slight defect, values +3,25 to +6,0 diopters represent medium farsightedness, from +6,25 to +9,0 diopters we talk about high defect. Serious defect (from +9,25 up) comes with impaired vision, but not only in the near but also for further objects.
You are legally blind when your visual acuity drops below 20/200 even with best possible correction or if you have a visual field less than 20 degrees. You are not legally blind as long as you can see 20/200 with your glasses.
20/30 to 20/60, this is considered mild vision loss, or near-normal vision. 20/70 to 20/160, this is considered moderate visual impairment, or moderate low vision. 20/200 or worse, this is considered severe visual impairment, or severe low vision.
Optometrists and government agencies usually define legal blindness as someone having 20/200 vision in the best eye, even with glasses or contacts, indicating a substantial deficit in vision. Low vision, on the other hand, is defined as having 20/70 vision in the best eye with glasses or contacts.
A refractive error greater than -6 is when an optometrist might diagnose high myopia in a patient. Low myopia can have a refractive error as low as -0.25, while moderate myopia caps out at -5.75. If left untreated and with age, high myopia can progressively worsen to a greater degree of refractive error.
Typically, eye doctors will set their limits to +6 for farsightedness, -12 for nearsightedness, and 6 diopters for astigmatism.
Before we jump into what each section means, as a general rule, the higher the numbers on your prescription, the worse your eyesight is and the stronger your prescription will be to provide the necessary correction. Mild: -0.50 to -3. Moderate: -3.25 to -5.00. High: -5.25 to -10.
Visual acuity less than 20/200 is considered legally blind, but to actually fit the definition, the person must not be able to attain 20/200 vision even with prescription eyewear. Many people who would be legally blind without eyewear can function well in everyday life with appropriate glasses or contact lenses.
Severe blindness – visual impairment category 4 in one eye and no visual impairment in the other eye.
Legally blind means a person has a corrected vision of 20/200 in their best-seeing eye. If visual aids such as glasses can correct a person's vision to 20/20, they are not considered legally blind. Totally blind refers to a complete loss of sight.
The highest level of corrective power for monthly soft contact lenses is about -12 Dioptres (bear in mind that the average prescription for short sighted people is -2.00 Dioptres), and is available from both Purevision 2HD and Biofinity.
Basically, if it is at least 20/70, is uncorrectable—even with contacts, glasses or surgery—and interferes with your daily activities, it can be legally considered “low vision.” In order to be legally blind, you must have a visual acuity of 20/200.
Your eyesight could be getting worse because you have an uncorrected refractive error. If you begin to struggle to see far away or close up, then you should visit your optician for an eye examination. Your optician is able to diagnose a multitude of vision problems and offer advice on how to manage them.
A person who cannot see at six metres what a normally-sighted person can see at 60 metres or has a field of vision restricted to 20 degrees diameter or less (normal field of vision is 180 degrees) or a combination of both (reduced visual acuity and field of vision) is considered legally blind.