The Definitions and Demographics of low visionPresentation Transcript
The Definitions and Demographics of Low Vision
• Low Vision • Partial Sight • Visual Impairment Reduced VA which even with the best optical correction provided by regular lenses still results in a visual performance on a standardised clinical test which is less than that expected for a patient of that age.
• impairment • disability • handicap The reduction in performance to below normal levels on some standard test of visual function. The lack, loss or reduction in the ability of a person to perform some task The fact or the feeling that a patient is placed at some disadvantage in society and cannot live their life as they might expect.
Loss of earning potential Reading problem VA loss central scotoma ARMD Loss of independence Mobility problem Peripheral field loss Glaucoma Loss of independence Night driving problem Disability glare cataract Social consequences Visual skills & abilities Functional changes Ocular disease Visual Handicap Visual Disability Visual Impairment Visual Disorder
Defining Low Vision a) Visual impairment b) Visual disability
Based on performance in a standard test
Where should the pass/fail boundary be set?
Based on some measure of performance in a functional task
- Very difficult to quantify such problems
Legal Blindness Most developed countries have social care systems which Provide benefits and care to certain groups. Registration is usually necessary in order to be eligible. Registration is undertaken in order to: • assess what health and social work resources will be needed for the number of visually impaired people in a particular area. • act as the patient’s passport to appropriate welfare benefits.
Therefore some legal definition of blindness is required. There are problems in achieving a consistent definition of Blindness. - WHO (1966) identified some 65 different definitions of blindness. - some countries (e.g. UK) have dual categories of partial sight and blindness.
The Registration System in the UK Blind Persons Act 1920
Legislated to provide welfare facilities for the blind.
Provides a definition of blindness which establishes eligibility.
(the partial sight category was added via the National Assistance Act 1948) Blind - ‘ so blind as to be unable to perform work for which eyesight is essential .’ Partial Sight - ‘ substantially and permanently handicapped by defective vision caused by congenital defect, illness or injury .’
There is obviously much scope for interpretation with this kind of definition therefore attempts have been made to quantify the degree of impairment: Blind - 3/60 or worse or, 6/60 or worse with markedly restricted fields Partial Sight - 3/60 – 6/60 with full visual field or, 6/24 or worse with moderate field constriction or, 6/18or better with gross field defect.
The BD8 form Patients can only be registered by an ophthalmologist who completes a BD8 form (BP1- Scotland, A655 – N.Ireland). Record of Examination to Certify a Person As Blind or Partially Sighted Advantages: • increases in tax allowances • reduction in TV licence • free General Ophthalmic Services • VAT exemptions on products designed for the disabled.
Legislation Relating to Low Vision The National Assistance Act 1948 Section 26 lays down the responsibilities of the local authority for those registered as blind and partially sighted. Additional to the Blind Persons Act 1920 • keeping registers of blind and partially sighted • providing a social work service, advice and support for those living at home or elsewhere • making available facilities for rehabilitation and for adjustment to the disability (e.g. teaching Braille). • providing facilities for social, recreational, occupational and cultural activities
The Chronically Sick and Disabled Act 1970 Dictates that an even wider range of services to be offered by the local Authority: • practical help and home adaptations • supply of radio/television • installation and rental charges for telephone • meals in the home or elsewhere.
The National Health Service and Community Care Act 1990 Legislates to provide those people with visual impairments with care services tailored to their own individual needs. A ‘care plan’ is devised which describes the unique requirements of the particular individual. If a need is identified which the local authority does not have the staff to provide then it is required to buy in the services
Demographics of Low Vision
The World-Wide demographics of Low Vision
The Global distribution of Blindness % blind from 37.9 28.3 0.9 13.5 15.5 41.8 Total (% of total blind) 2.4 1.1 2.3 6.7 3.6 5.8 8.9 7.1 89.0 85.0 27.4 27.6 23.4 19.8 20.0 19.8 0 0 0.1 0 0 0 5.1 0.9 7.5 6.7 7.9 22.6 5.7 16.8 12.8 12.0 0 0 6.9 17.5 25.7 23.5 9.7 19.4 3.5 8.3 57.7 32.3 45.2 39.9 57.5 43.7 Europe, USA, Japan, NZ Former Communist European states Latin America & Caribbean China Middle East Other Asia & Islands India Sub-Saharan Africa TOTAL (millions) Others Oncho- Cerciasis Glaucoma Trachoma Cataract Region
Major causes of Blindness World-wide Cataract 42% Trachoma 15.5% Glaucoma 13.5% Onchocerciasis 0.9% Others 28.1%
The UK Perspective
Demographic information on low vision can be taken from 3 sources: 1. Low Vision Clinics 2. Blindness Registration Data 3. Disability Questionnaires There are difficulties with each of these sources.
The total number of those registered as blind and partially sighted In the UK. 79,050 93,780 115,710 1988 1991 1994 126, 830 136,200 149,670 Partially Sighted Year Blind
Registration (via BD8) - Avoidance of social stigma - Poor appreciation of low vision - Voluntary Result Under registration According to an RNIB study (Bruce et al., 1991) x 4 more People are eligible for registration
Elliot et al., (1997) Invest Ophthalmol & Vis Sci Age profile of Px’s who visit low vision clinics 0-14 15-34 35-54 55-64 65-74 75-84 85+ 0 5 10 15 20 25 30 Female Male Age group (years) Percentage
Of the 4,744 Pxs seen in this study - 71% > 65 - 55% >76 - the majority of these elderly people were females
57% of the elderly also had other functional impairments
e.g. hearing, mobility etc.
in addition to the primary cause of visual impairment the Pxs frequently had
secondary ocular problems the most common of which was cataract.
20 50 80 0-17 18-49 50-64 65-74 >75 Registration Figures for England in 1994 0 10 30 40 60 70 Age Group Blind Partially sighted 65-74 Percentage of Total
ARMD 75.49% Other 10.39% Glaucoma 6.01% Diabetic ret. 4.57% Cataract 3.53% Major causes of Blindness in the UK in > 65yrs
Actual & Projected increase in population > 85 yrs
The role of the Optometrist Early detection of pathology If impairment is not avoided then will be involved in the assessment and prescription of an appropriate Low Vision Aid (LVA). magnifiers (hand, stand, flat field etc.) telescopes spectacle microscopes and so on.
What do Pxs want from a low vision examination? Personal reading 75.17% Daily living activities 14.45% Other 7.32% Watching TV 3.06%
5.2 9.1 1.2 15.7 9.9 18.2 27.7 5.7 7.3 Absolute blindness (NPL) Perception of light Perception of light with detection of direction 6/240 6/240 – 6/120 6/120 – 6/60 6/60 Restricted visual fields with acuity > 6/60 Unknown % of blind population Visual Impairment
Functionally Blind These form a relatively small proportion of the blind population.
unable to read of write visually
unable to move or orientate visually
unable to recognise objects visually
SENSORY SUBSTITUTION e.g. Braille Many legally blind people have some residual visual function VISUAL ENHANCEMENT e.g. LVAs
Service delivery model
The Multi-disciplinary Approach to Low-vision Care. The consequences of visual impairment may affect many aspects of a Px’s life. Any low vision treatment must include a comprehensive look at all the individual’s needs (vocational, educational, social, psychological,financial, optometric, medical …..). Ophthalmologist Optometrist Social workers Occupational Therapist Rehabilitation worker