The criteria for certification

On this page we tell you how an eye specialist decides if you can be certified as severely sight impaired (blind) or sight impaired (partially sighted) by an eye specialist (a consultant ophthalmologist).

What happens when you see the eye specialist

The eye specialist, called a consultant ophthalmologist, will decide 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.

Your visual acuity is measured by reading down an eye chart while wearing any glasses or contact lenses that you may need, so remember to bring them to your appointment. The test for visual acuity is known as a Snellen test. Your field of vision is measured by a “visual field test”.  There are guidelines about the level of sight needed to be registered severely sight impaired (blind) or sight impaired (partially sighted).

The consultant may do other tests to check your eye health. This could mean they use drops to dilate (open) your pupils, which can blur your vision for a few hours afterwards. You may want to have someone with you to help you home after the appointment.

After the ophthalmologist has assessed your vision and your eyes, they will decide if you are eligible for your sight loss to be certified. The consultant can certify you as either severely sight impaired (blind) or sight impaired (partially sighted) by completing the Certificate of Vision Impairment (CVI) in England and Wales. In Scotland it’s called BP1, in Northern Ireland it’s called A655.

If your sight is affecting your ability to drive safely, you need to inform the DVLA on 0300 790 6806.

The Snellen test for visual acuity

Visual acuity is measured using the Snellen scale. A Snellen test usually consists of a number of rows of letters which get smaller as you read down the chart.

On the Snellen scale, normal visual acuity is called 6 / 6, which corresponds to the bottom or second bottom line of the chart. If you can only read the top line of the chart then this would be written as 6 / 60. This means you can see at 6 metres what someone with standard vision could see from 60 metres away.

The figures 6 / 60 or 3 / 60 are how the result of a Snellen test are written. The first number given is the distance in metres from the chart you sit when you read it. Usually this is a 6 (for 6 metres) but would be 3 if you were to sit closer to the chart (3 metres away).

The second number corresponds to the number of lines that you are able to read on the chart. The biggest letters, on the top line, correspond to 60. As you read down the chart, this number gets smaller as it correspond to the lines with smaller letters. Someone with standard vision can read towards the bottom of the chart. Standard vision can be referred to 6 / 6 vision.

For example, if the second line of the chart was marked as the 36 line, a person with standard vision (6 / 6) would be able to read this line on the chart when it was 36 metres away. However, if you had a Snellen score of 6 / 36, you would only be able to read the same line at 6 metres away. In other words you need to be much closer to the chart to be able to read it. Generally the larger the second number is, the worse your sight is.

What the results of your vision test mean for your certification

The ophthalmologist uses a combination of both your visual acuity and your field of vision to judge whether you are eligible to be certified, and at which level. If you have a good visual acuity, you will usually have had to have lost a large part of your visual field to be certified as severely sight impaired (blind) or sight impaired (partially sighted).

Alternatively, if you have all your visual field, you will usually have to have a very poor visual acuity to be certified as severely sight impaired (blind) or sight impaired (partially sighted).

Generally, to be certified as severely sight impaired (blind), your sight has to fall into one of the following categories, while wearing any glasses or contact lenses that you may need:

  • visual acuity of less than 3 / 60 with a full visual field
  • visual acuity between 3 / 60 and 6 / 60 with a severe reduction of field of vision, such as tunnel vision
  • visual acuity of 6 / 60 or above but with a very reduced field of vision, especially if a lot of sight is missing in the lower part of the field.

To be certified as sight impaired (partially sighted) your sight has to fall into one of the following categories, while wearing any glasses or contact lenses that you may need:

  • visual acuity of 3 / 60 to 6 / 60 with a full field of vision
  • visual acuity of up to 6 / 24 with a moderate reduction of field of vision or with a central part of vision that is cloudy or blurry
  • visual acuity of 6 / 18 or even better if a large part of your field of vision, for example a whole half of your vision, is missing or a lot of your peripheral vision is missing.

If your eye specialist does certify you

The eye specialist sends copies of the certificate to you, your GP and your local social services department. You can then choose to be registered with your local social services if you wish to.

If your eye specialist tells you that you cannot be certified

Your eye specialist might tell you that you cannot be certified at present. This could be for one of three reasons:

  • you haven’t met the criteria for visual acuity and field of vision
  • or that they feel your sight loss isn’t permanent
  • or that, if you are already receiving treatment that could improve your sight, they may wish to wait for the outcome of that treatment.

Whatever the reason, if you feel strongly that you should be certified then talk to your GP about referring you to a second specialist. Bear in mind though that this second specialist will have to follow the same rules for the certification process.

Remember that you can still get help from social services even if your sight loss cannot be certified.

Questions about the criteria for certification

Call our Helpline on 0303 123 9999 if you have questions or concerns about certification or registration. Our trained advisers can talk you through what’s involved.

You can also email your questions to

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