Visually Impaired: Meaning, Levels and Types of Blindness

By Carlos Acosta · October 30, 2026 · 10 min read

"Visually impaired" means having reduced sight, anywhere from a mild loss to total blindness. The World Health Organization (WHO) says a vision impairment occurs when an eye condition "affects the visual system and one or more of its vision functions" (WHO World report on vision). It's an umbrella term, not one level: WHO sorts it into mild, moderate and severe vision impairment, blindness, and near vision impairment.

Below: the WHO levels with their exact numbers, the words used in the US, the UK and Canada, the types of blindness, how many people are affected, and what organizations of blind people say about the term itself. Official pages were checked on October 30, 2026. This explains what they say; it isn't medical advice.

Key points

It's an umbrella word. It covers everyone from people with mild sight loss to people who see nothing at all, so many people it describes still have some sight.
WHO measures the better eye. Mild impairment starts when acuity is worse than 6/12; blindness is worse than 3/60, or a central visual field narrower than 10 degrees (WHO).
The words change by country. WHO says "vision impairment"; the UK certifies people as "sight impaired" or "severely sight impaired"; US law uses "blindness" and the 20/200 line known as legally blind.
Blindness has types too. Total blindness means no light perception. Partial blindness, congenital blindness and cerebral visual impairment are different things.
At least 2.2 billion people have a near or distance vision impairment, according to WHO's fact sheet updated February 10, 2026.
Not everyone likes the term. CNIB in Canada advises avoiding "visually impaired" unless a person chooses it, and RNIB in the UK prefers "sight loss".

Visually impaired at a glance

Term	What it means	Where it's used
Vision impairment	Any reduced vision, from mild to blindness	WHO, worldwide
Visually impaired	The everyday adjective for the same range	Common, especially among professionals (RNIB)
Low vision	Sight loss that glasses or surgery can't fix and that makes daily tasks hard	NEI, US
Sight impaired (partially sighted)	The less severe of two registration levels	UK
Severely sight impaired (blind)	The more severe registration level	UK
Legally blind	20/200 or less in the better eye with correction, or a field of 20 degrees or less	US law
Totally blind	No light perception	WHO, AFB

Sources: WHO World report on vision, NEI, GOV.UK, 42 U.S.C. 416, WHO ICD-10, AFB.

What "visually impaired" means

"Visually impaired" is the adjective; "vision impairment" or "visual impairment" is the noun. Both describe the same thing: an eye condition that reduces how well someone sees. Doctors and surveys measure it mainly by visual acuity (how small a detail you can see) and by the visual field (how wide an area you can see without moving your eyes).

WHO measures vision as the person comes to the exam. If someone wears glasses or contacts, they're tested with them on, and if those correct their sight, WHO says they "will be categorized as not having a vision impairment" (WHO World report on vision, Box 1.4). So needing glasses doesn't by itself make someone visually impaired.

Visually impaired isn't the same as blind. Blindness is one level inside the range. In everyday speech, though, "blind" is often used more broadly too. CNIB, Canada's national blindness organization, says "people who are blind" covers the "full spectrum of visual disability, from mild to significant," and that many people with some remaining vision call themselves blind (CNIB Inclusive Language Guidelines).

RNIB, the UK's Royal National Institute of Blind People, notes that "visually impaired" is more "commonly used by professionals in the health, social care and education sectors" (RNIB workbook). That's why it shows up on school forms, medical letters and job applications.

The WHO levels of vision impairment

Distance vision is measured with a chart at 6 meters (20 feet). The result is written as a fraction: 6/18 means a person reads at 6 meters what someone with normal vision can read at 18 meters, and WHO takes normal vision to be 6/6 (WHO, Box 1.2). In the US the same chart is written over 20, so 6/18 becomes 20/70.

WHO level	Visual acuity in the better eye
Mild vision impairment	Worse than 6/12, but 6/18 or better
Moderate vision impairment	Worse than 6/18 (20/70), but 6/60 (20/200) or better
Severe vision impairment	Worse than 6/60 (20/200), but 3/60 (20/400) or better
Blindness	Worse than 3/60 (20/400)
Near vision impairment	Near acuity worse than N6 or M 0.8 at 40 cm

Sources: metric values from the WHO World report on vision (2019), Box 1.2; values in feet are WHO's own equivalents in ICD-10, H54. WHO's tables give no feet value for 6/12.

Three details from the same pages:

The visual field counts too. Severe impairment and blindness can also be set by the central visual field of the better eye, when it narrows to less than 20 degrees (severe) or 10 degrees (blindness).
Near vision is about print. N6 is a print size; WHO describes it as "a font size equivalent to newspaper print," read at 40 centimeters.
WHO's report is aligned with ICD-11. It says its definition of vision impairment is compatible with the International Classification of Diseases 11th Edition (ICD-11).

The three levels of blindness

WHO's ICD-10 splits blindness into three categories (ICD-10, H54):

Category 3: worse than 3/60 (20/400), down to 1/60 (20/1200), or counting fingers at 1 meter.
Category 4: worse than 1/60, down to light perception.
Category 5: no light perception.

The World report on vision says this split was added in 2010 to tell apart people with "no perception of light" from those who still perceive light (Box 1.3).

What happened to "low vision" in the WHO tables

Older WHO tables had a "low vision" category. ICD-10 replaced it with the moderate and severe levels "to avoid confusion with those requiring low vision care" (ICD-10, H54). The phrase is still common outside those tables, as the next section shows.

The words people use, and where

Low vision (US)

The US National Eye Institute (NEI) says: "Low vision is a vision problem that makes it hard to do everyday activities." It "can't be fixed with glasses, contact lenses, or other standard treatments" (NEI). WHO lists optical magnifiers and improved lighting among vision rehabilitation options (WHO World report on vision); our guide to low vision aids covers these and large print.

Partially sighted, sight impaired and severely sight impaired (UK)

In England, a consultant ophthalmologist can sign a Certificate of Vision Impairment (CVI). It certifies a person as sight impaired, "previously referred to as partially sighted," or as severely sight impaired, "previously referred to as blind" (GOV.UK explanatory notes). The NHS uses the same pairs and says a person can then register with their local authority (NHS). Our guide to being registered blind in the UK explains the criteria and what registration gives access to.

US law defines blindness as central visual acuity of 20/200 or less in the better eye with a correcting lens, or a visual field no wider than 20 degrees (42 U.S.C. 416). It's a legal line used by programs, not a WHO level; What is legally blind? explains it in detail.

"Totally blind" means no light perception, WHO's category 5. The American Foundation for the Blind (AFB) describes total blindness as "the complete lack of light perception and form perception," recorded as NLP (AFB).

Canada

CNIB suggests "people who are blind, Deafblind, or have low vision" to cover the whole range. It treats "partially sighted" as an alternative to low vision, "best used when describing people who have some usable vision" (CNIB).

Types of blindness

Total blindness and light perception

Total blindness is no light perception at all. Light perception is the level just above it: AFB gives the example of knowing "when a room light is on or off" (AFB). Both count as blindness in WHO's categories. How much each person sees varies; what blind people see describes the range.

Partial blindness: central loss, peripheral loss and blurred vision

"Partial blindness" and "partial sight" are older names for low vision. AFB says: "Those descriptions are no longer in general use." NEI lists the main kinds of low vision (NEI):

Central vision loss: "not being able to see things in the center of your vision."
Peripheral vision loss: not seeing things out of the corners of the eyes.
Night blindness: not seeing in low light.
Blurry or hazy vision.

Congenital and acquired blindness

Congenital blindness is blindness present from birth; acquired blindness comes later in life. WHO's report says the main conditions in children and young adults include "congenital, genetic, and acquired eye conditions" (WHO World report on vision). CNIB's language guide makes the same split when it suggests "people with sight loss" for people "born with sight and lost some or all of their vision later in life." What blind people see compares people born blind with people who lost their sight later.

Cortical or cerebral visual impairment (CVI)

Cerebral visual impairment, also called cortical visual impairment, is "caused by damage to the parts of the brain that process vision." The eyes may work, but the brain has trouble processing what they send. NEI calls it "a leading cause of vision loss among kids in the United States" (NEI). Don't confuse it with the UK's CVI, the Certificate of Vision Impairment. More in our guide to cortical visual impairment.

Color blindness is not blindness

Despite its name, color blindness means you "see colors differently than most people" (NEI). WHO's ICD-10 files it under colour vision deficiencies (H53.5), apart from H54, "Visual impairment including blindness" (ICD-10).

How many people are visually impaired?

WHO's fact sheet, updated February 10, 2026, says: "Globally, at least 2.2 billion people have a near or distance vision impairment." For at least 1 billion of them, it "could have been prevented or is yet to be addressed," and most people with vision impairment and blindness are over 50 (WHO fact sheet). WHO's World report on vision (2019) gave the same figure of at least 2.2 billion. In Canada, CNIB says "1.5 million Canadians live with sight loss."

Organizations of and for blind people don't use the same words, but their advice is close:

National Federation of the Blind (US). Its 1993 Resolution 93-01 rejects euphemisms for blindness. It calls terms like "visually impaired" "undesirable when used to avoid the word blind," and acceptable only when used to tell apart people with some sight from people with none (NFB Resolution 93-01, Internet Archive copy).
CNIB (Canada). Its guide says it's best to "avoid this term unless an individual specifically chooses" it, because many people find it focuses on the negative. It adds that the word "blind" is "perfectly fine to say," while "the blind" is outdated (CNIB).
RNIB (UK). Its preferred term is "sight loss", followed by alternatives such as "blind and partially sighted people" (RNIB).

The common rule: use the word the person uses for themselves. CNIB asks people to "respect the way people choose to refer to their own blindness or sight loss."

Reading with a vision impairment

People with a vision impairment read in several ways, depending on how much they see. WHO lists "reading using Braille, screen readers" among vision rehabilitation options (WHO World report on vision). The NHS says support can include help using low vision aids and assistive technology for reading (NHS); low vision aids covers magnifiers and large print. People who see little or nothing use braille (what is braille), audio and screen readers (how blind people read). To start with braille, see how to learn braille.

Where Braillito fits

Braillito, our app, teaches braille. It teaches the braille cells in lessons with exercises you play, with lives, levels and a daily streak: 59 lessons in 8 worlds in English. It also has a translator, a dictionary and a cell builder. The English lessons are uncontracted braille (grade 1); they don't teach contracted braille or transcription, and Braillito isn't a braille transcriber.

Braillito teaches braille, one of the reading options above; it doesn't test vision or replace an eye exam. Without paying, the braille translator works in any browser.

Braillito is a subscription with no free version; depending on the plan, it starts with a free trial or a discounted first period, if it's your first subscription (is Braillito free?). Get Braillito.

Frequently asked questions

What does visually impaired mean?

It means having reduced sight, from a mild loss to total blindness, even with the glasses or contacts a person uses. WHO splits it into mild, moderate and severe vision impairment, blindness, and near vision impairment, measured in the better eye (WHO).

No. Blindness is the most severe level of vision impairment: in WHO's table, acuity worse than 3/60 (20/400) in the better eye, or a central field under 10 degrees. Many visually impaired people have useful sight. In the US, "legally blind" is a separate legal line at 20/200; see what is legally blind.

What are the types of blindness?

The sources describe total blindness (no light perception), blindness with light perception, partial blindness or low vision (central loss, peripheral loss, blurred vision), congenital and acquired blindness, and cerebral visual impairment, which comes from the brain rather than the eyes (NEI). Color blindness isn't one of them.

Can a visually impaired person read?

Yes. People with low vision often read large print or use magnifiers; people who see little or nothing read braille by touch or listen with audio and screen readers. To start with braille, see how to learn braille.