Legal blindness is a term used to define a specific level of vision impairment that qualifies an individual for benefits and assistance. In the UK, legal blindness is assessed based on visual acuity and visual field rather than a specific eye prescription. This article explores the criteria for legal blindness in the UK, how it relates to eye General prescriptions, and what support is available for those affected.

Legal Blindness Criteria in the UK

In the UK, an individual is considered legally blind (also known as “severely sight impaired”) if they meet one of the following criteria:

1. Visual Acuity of 3/60 or Worse – This means that an individual can only see at 3 meters what a person with normal vision can see at 60 meters.
2. A Visual Acuity Between 3/60 and 6/60 with a Severely Restricted Visual Field – If a person has slightly better acuity but a severely reduced field of vision, they may also qualify.
3. A Visual Acuity of 6/60 or Better with a Severely Reduced Visual Field – This applies to those who have better central vision but extreme tunnel vision (e.g., a visual field of less than 20 degrees).

How Eye Prescription Relates to Legal Blindness

An eye prescription, usually written in terms of diopters (D), measures refractive errors like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. However, a prescription alone does not determine legal blindness.

To provide a general reference:

• A prescription of -6.00 D to -10.00 D (high myopia) can result in significantly blurred vision but does not necessarily indicate legal blindness.
• A prescription beyond -10.00 D is considered extreme, but some individuals with strong corrective lenses may still function well.
• If someone has a prescription of -20.00 D or worse, their uncorrected vision may be close to the legal blindness threshold, but visual acuity after correction is what matters most.

Assessment for Legal Blindness

An optometrist or ophthalmologist assesses vision using:

• Snellen Eye Chart Test – Measures visual acuity and determines if it falls within the legal blindness range.
• Visual Field Test – Evaluates peripheral vision, crucial for determining if someone qualifies as legally blind.

If an individual meets the legal blindness criteria, they may be certified by an eye specialist through a Certificate of Vision Impairment (CVI), which allows access to various support services.

Support Available for Legally Blind Individuals

Once certified as legally blind, individuals in the UK can access:

• Disability Benefits – Including Personal Independence Payment (PIP) and Attendance Allowance.
• Access to Low Vision Aids – Magnifiers, screen readers, and adaptive technologies.
• Guide Dogs and Mobility Training – Assistance with daily navigation and independence.
• Tax and Travel Concessions – Discounts on public transport and tax exemptions.

In the UK, legal blindness is not determined solely by an eye prescription but by visual acuity and visual field loss. While high myopia or other refractive errors can cause severe vision impairment, an individual must meet specific medical criteria to be classified as legally blind. Those who qualify can receive essential support to improve their quality of life and independence.