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Eye Conditions

How bad does your visual impairment need to be to be registered as a blind or partially sighted person?

The definition of blindness used in registration is still taken from the National Assistance Act 1948, which states that a person can be certified as blind if they are ‘so blind that they cannot do any work for which eyesight is essential’.

Your eye specialist (a consultant ophthalmologist) will decide if you can be certified as severely sight impaired (blind) or sight impaired (partially sighted) according to whether you meet the criteria for certification by measuring your:

  • Visual acuity – your central vision, the vision you use to see detail.
  • Visual field – how much you can see around the edge of your vision, while looking straight ahead.
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Eye Conditions Glossary

We have put together a glossary for various eye conditions, including their symptoms and treatments.

Please click on the links below to find out more.

Cataracts

Clouding of the lens of the eye causing light to scatter and vision to blur

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Charles Bonnet Syndrome

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Detached Retina

Where the inside layer (retina) of the eye detaches and, although symptoms can vary, commonly a dark shadow affects vision

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Diabetic Retinopathy

A complication of diabetes where the blood vessels at the back of the eye leak and rupture with loss of vision

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Glaucoma

Where the pressure within the eye ball increases and there is a loss of side vision leading to tunnel vision

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Macular Degeneration – Wet and Dry

Sometimes known as Age Related Macular Degeneration (ARMD) where the rear central (and most sensitive) part of the eye begins to degenerate leaving a ‘dark or blank hole’ in your vision

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Nystagmus

This is characterised by uncontrollable movements of the eyes either from side to side or up and down. The constantly moving image causes blurring

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Retinitis Pigmentosa

A hereditary condition affecting the retina resulting in poor vision in poor light and restriction of visual field and tunnel vision

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Terms often used when talking about different levels of sight loss:

Blindness

does not necessarily mean a person is totally without sight, although of course it can do. Some people may have no vision at all, others may have some perception of light only and others will have varying levels of residual vision.

Long-sightedness (Hypermetropia)

is where someone has difficulty seeing things which are close by e.g. reading or sewing.

Low vision

refers to a severe visual impairment where people are unable to read print at a normal viewing distance even with the aid of spectacles or contact lenses.

Partially sighted

Refers to having a significant degree of sight loss that cannot be fully corrected with glasses or contact lenses, but where vision is still present, allowing for some level of visual function.

Registered blind

The term ‘registered blind‘ is used when the vision of a person is reduced so much it meets a laid down criterion and the person wishes for this to be officially recognised as a disability.

Short-sightedness (Myopia)

is where someone has difficulty getting a clear image of objects which are in the distance e.g. difficulty in reading notice boards, problems seeing traffic approaching etc.

Visual acuity

is a term used to describe the sharpness of the images seen. It is generally measured by a Snellen Chart which has nine rows of letters in decreasing sizes. Perfect vision can be expressed as a group of numbers i.e. 20/20, which means an individual can see the same detail at 20 feet as a standard observer can.

Visual field

refers to what can be seen centrally (straight-ahead) and peripherally (off to each side and up and down).

Visual processing disorders

refers to problems regarding making sense of what is seen through the eyes, i.e. a difficulty in the brain interpreting what it is seeing.

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