oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
There is a legend of a blind, illiterate minstrel of Asia Minor, who begged his way from door to door singing his immortal verses. This man was Homer (G: homeros; blind man). Over hundreds of years, other blind people have followed who have made their mark in history such as John de Turcznow (known as Zisca), a brilliant military general, the celebrated English poet, John Milton and a number of princes (George V of Hanover, Prince Hitoyasu of Japan) to name but a very few.
But the concerns and worries of our patients are far removed from these epic characters. They vary from one individual to the next depending on their age, circumstance and their personality. For one, there may be the fear of social isolation, for another, not being able to do the cross-word. There may also be concerns regarding:
- Maintaining independence (mobility, driving)
- Activities of daily living (reading, writing, television)
- Issues surrounding financial support
In the case of children and younger people, there is also the important element of education and finding or keeping a job.
There is no legal definition of sight impairment or partial sight. However, convention is that partial sight involves:
- A visual acuity from 3/60 to 6/60 with a full field
- Up to 6/24 with moderate restriction of visual field, opacities in the media or aphakia
- 6/18 or better with a gross field defect (eg, hemianopia) or a marked constriction of the field (eg, glaucoma or retinitis pigmentosa)
Blindness is legally defined as 'so blind that they cannot do any work for which eyesight is essential'. In practice, this translates into:
- A best corrected visual acuity below 3/60 or 1/18
- A best corrected visual acuity better than 3/60 but below 6/60 with a very restricted visual field
Severe visual impairment is the term now used for blindness.
- About 2.5% of the UK population have some degree of visual impairment that is not correctable by refraction and about two-thirds of these are thought to have sufficiently severe problems to qualify for registration.
- The vast majority are older people (over 65 years of age) but there are 80,000 people of working age and 25,000 children affected.
- At the end of March 2006 there were 364,615 people in the UK who were registered as severely sight impaired (blind) or sight impaired (partially sighted).
- Every day, another 100 people begin to lose their sight.
Causes of blindness
There are a great number of causes of blindness ranging from congenital or hereditary conditions through to the more frequently encountered acquired diseases. The most common cause of gradual onset bilateral blindness in the developed world is macular degeneration. Diabetic retinopathy is the second most common cause. Other causes include:
- Diabetic maculopathy
- Hypertensive retinopathy
- Chronic glaucoma
- Chiasmal or bilateral optic nerve compression
- Bilateral optic nerve damage - eg, tobacco amblyopia
- Worldwide, chlamydial infection causing trachoma is a common cause
Sudden bilateral loss of vision is rare and is an ophthalmological emergency which requires immediate referral to the eye emergency department. Possible causes of rapid onset blindness includes:
- Bilateral occipital lobe ischaemia or infarction
- Bilateral occipital lobe trauma
- Severe bilateral papilloedema
- Rapidly progressive chiasmal compression
- Bilateral optic nerve damage - eg, methyl alcohol poisoning
More commonly, a new problem may develop in one eye on the background of sight impairment due to pre-existing disease in the fellow eye.
Managing initial reactions
Patients will come to learn about their visual impairment in a variety of ways. Some will be a part of the significant proportion who never seek help and who bear the weight of their disease alone. You may never meet them. Many others will have had a formal diagnosis by an ophthalmologist. These patients will have had to take on board the reality of what the problem is, what the treatment options are (and are not) and any other associated information in a very short space of time - maybe a matter of minutes.
You may be left with the consequences of managing the subsequent reactions as the news sinks in. It is tough facing a person who has been told that they or their relative will be going blind or is irretrievably sight impaired. There are no perfect solutions to managing this and it will depend on your time, your knowledge of the patient and of the condition. It may be helpful to be aware of the following:
- Patients often go through a series of initial reactions to news of a chronic disease:
- Shock - this is most pronounced if the diagnosis comes without warning. It is characterised by a feeling of bewilderment, behaving in an automatic fashion and having a sense of detachment. It may last from hours to weeks.
- Encounter reaction - the individual is overwhelmed by the reality and seems unable to think clearly or plan effectively.
- Retreat - the health problem or its implications may be denied.
- There are few conditions where the sight completely goes to no perception of light. Most retain some sort of visual perception. For example even in severe macular degeneration, peripheral vision will be maintained.
- The statement 'nothing can be done' is rarely true - see below.
- What visual acuity remains needs to be optimised by good, up to date refraction. Encourage patient to see an optician.
- Remind patient of good lighting: use brighter bulbs, more lights round the house and use a good reading light.
- Enhance contrast where possible such as using large print books (don't forget talking books, the radio).
- Encourage patient or relatives to find local support groups - these may be found through the Royal National Institute of Blind People's generic website (see below) or by looking up specific conditions.
- Consider referral to a low visual aids clinic (contact your Eye Department for local arrangements) where further advice can be given especially with regards to optical devices. These may include magnifiers, telescopes, close circuit TV, computers, talking watches, writing guides, liquid level indicators, talking scales, etc.
Visual impairment registration
Each local authority keeps a register of blind and partially sighted people living in its area. The register is held by the social services department or by the local voluntary society for people with sight problems acting as agents for the local authority. The register is confidential. Registration is voluntary but it is helpful in getting extra support. However, anyone having difficulties because of poor sight, is entitled to ask their local social services department to assess their needs, even if not yet registered.
Referral forms for people who are visually impaired
There are several possible forms, the last of which (CVI) is the only one conferring a status of registration as visually impaired:
- Form LVI: self-referral letter which a person with problems of sight loss can send to social services if they wish to be contacted for help and advised on what services are available locally and nationally. The form is available to be given by optometrists/opticians to appropriate patients.
- Form RVI: may be issued by staff in the hospital eye service to refer the patient (with consent) for a social care assessment. It should be used as soon as social needs become apparent but where certification is not appropriate at this time or cannot be carried out (for instance, they are not being seen by a consultant). Hospital eye services are able to download it from the NHSweb at or from Department of Health website.
- Form CVI performs has replaced the previously used form BD8. It formally certifies someone as sight impaired (partially sighted) or as severely sight impaired (blind) so that the local council can register him or her. The signature of a consultant ophthalmologist certifying eligibility to be registered is required on a CVI before registration can be offered. Registration is voluntary but entitles people to various benefits and concessions.
Benefits of registering as blind or partially sighted
The purpose of the register is to help local authorities provide the best service they can for people who have sight problems. To do this, they need a record of all the blind and partially sighted people in their area and what kind of services they need. The statutory requirements are that:
- An assessment of needs is carried out.
- Information about services for visually impaired people is provided in a format accessible to the individual.
On receipt of the appropriate form, social services contact the person who is sight impaired about being added to the register. Social services assess the person's needs and any support that would help.
The social services department should arrange a community care assessment, with input from a worker for blind and partially sighted people.
Registration will confer a number of benefits, the extent and exact nature of which depend on whether the person is registered as severely visually impaired (ie blind) or partially sighted. These include:
- Tax relief and allowances eg disability living allowances, additional income support/pension credit, council tax reduction, etc.
- Community care services eg trained staff who can provide support for a range of activities, including safe mobility indoors and out, skills for daily living such as cooking and leisure activities
- Referral to other local services for collateral help.
- Financial support eg free prescriptions and low visual aids, railcard and other travel concessions, free postage on 'articles for the blind', car park blue badge, reduction in TV licence fee (50%), free loan of radio, etc.
There is surprisingly little evidence to suggest that visual impairment alone causes accidents. However, there is an onus on the patient to contact the DVLA should there be any significant change in the patient's vision and document your instruction to the patient to do so. Failure for a driver to reach the standards set out below results is a criminal offence with a penalty of up to £1000.
- Visual acuity - the requirement to drive a car or ride a motorcycle is that the person must be able to read in good light (with the aid of glasses or contact lenses if worn) a registration mark fixed to a motor vehicle and containing letters and figures 79 millimetres high and 50 millimetres wide at a distance of 20 metres (plates dating post September 2001) or at a distance of 20.5 metres where the characters are 79 millimetres high and 57 millimetres wide (pre September 2001 font). This corresponds roughly to 6/10 on the Snellen visual acuity chart.
- Visual field - the minimum field of vision for safe driving is defined as field of at least 120° on the horizontal, and there should be no significant defect in the binocular field which encroaches within 20° of fixation above or below the horizontal meridian. Occasionally, if there is a static defect to which they have fully adapted, the DVLA may consider them as an 'exceptional case' following a practical driving assessment.
- Group 2 licences (includes large lorries and buses) - new applicants are barred in law if the visual acuity, using corrective lenses if necessary, is worse than 6/9 in the better eye and 6/12 in the worse eye. The uncorrected acuity in each eye must be at least 3/60. There must be a full binocular field of vision.
- Racing drivers - there are more stringent rules for this group of people who generally have to have a minimum of 6/6 best corrected visual acuity and a visual field of 120° without any significant defect within 20° above or below the horizontal meridian.
- Pilots - there are strict rules set out that involve visual acuity, degree of refractive error and correction, colour vision, visual fields and a number of other factors. Standards are marginally different for commercial and private pilots but they are all beyond the visual means of the partially sighted or visually impaired individuals considered in this record.
- UK armed forces - this depends on the area of work as each military section has specific requirements. Standards should be checked at the local forces career advice centre. Pilots and navigators or observers have higher visual standards imposed on them.
The difficulties experienced by anyone with significant sight loss can have a devastating effect if they are not properly advised and supported. In the provision of support, the needs, views and independence of the person with sight loss are of paramount importance. The list of possible complications is very long but includes:
Further reading & references
- Macular Disease Society; Home page; Excellent source of information on all aspects of condition.
- Royal National Institute of Blind People (RNIB)
- National Blind Children's Society; Support and advice specifically for issues relating to children and young people.
- Guide Dogs for the Blind Association.
- Denniston AKO, Murray PI; Oxford Handbook of Ophthalmology (OUP), 2009
- RNIB; Statistics on sight problems (November 2008).
- Sarafino EP. Health Psychology - Biosocial interactions (2nd ed.) J Wiley (1994).
- RNIB; Registering as blind or partially sighted.
- Department of Health; The identification, referral and registration of sight loss: Action for social services departments and optometrists, and explanatory notes. December 2003.
- At a glance guide to the current medical standards of fitness to drive; Driver and Vehicle Licensing Agency
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
|Original Author: Dr Olivia Scott||Current Version: Dr Olivia Scott|
|Last Checked: 23/05/2011||Document ID: 1874 Version: 25||© EMIS|