The Organisation of Low Vision Services in the UK
There is now an awareness worldwide that low vision services should aspire to adopt a holistic rehabilitative approach, rather than relying solely on providing low vision aids (LVAs). This has led to an acknowledgement that one single professional group is not best placed to deliver all aspects of such a service, and that a multidisciplinary team is required. However, there is no evidence to support the most effective model for this delivery. In the United States and Australia, there are multidisciplinary services where all the required professionals are available in a single location, but in the UK, this is extremely rare. provided profiles of the different types of low vision service (integrated and multiagency) in the UK, highlighting features of their different ways of working.
Regardless of location, those providing low vision services are always attempting to make them as inclusive as possible, with no barriers to individuals who have a need for the services ( ). It is desirable that referral into the service can come from any source, including self-referral; that there are no fixed acuity or field standards which need to be met for eligibility; and that patients can refer themselves back into the service whenever required. Recommended standards for low vision clinics encompassing the built environment, staffing requirements, communication strategies and the need for audit have been published ( ).
In the UK, the provision of optical aids for visually impaired patients by optometrists and dispensing opticians was relatively well-established prior to the increase in scope of low vision care. Therefore, a multidisciplinary approach was developed by those involved trying to improve the links between clinical services (often based in hospitals), community-based social low vision services and the voluntary sector ( ). Concurrently, there was a growing need to increase the availability of services to meet demand, and in England, ‘Adult Low Vision’ became one of a number of enhanced clinical pathways which could be commissioned in primary care at a local level. Commissioning arrangements are negotiated via the Local Optical Committee (LOC), and sometimes practitioners require additional training and accreditation to be eligible to participate. Typically, these schemes allow for practitioners to be paid a fee for assessment and follow-up, with optical aids (from an agreed inventory) provided to the patient free of charge. Guides are available for commissioners which detail the features they should expect to find in a local scheme ( ; ).
The Low Vision Service Wales (LVSW) is a similar government-funded primary care-based service which operates from optometric practices throughout Wales, with the advantage over the English system that it is a national rather than local scheme. The LVSW has been shown to achieve the aims intended for all such community-based provision of increasing availability of appointments and reducing travel time ( ). At the time of writing, a similar scheme is being developed in Scotland.
It should be emphasised that ‘low vision care’ is not an exclusive specialist area, but rather a key part of the role of any primary care optometrist ( ). Being able to offer practical advice on lighting, glare avoidance and contrast; offering a reading addition over +3.00; encouraging self-referral to social services; and signposting to charities should be a minimum requirement in any setting (although there is much more that could be done!). A brief explanation of the accessibility features of devices such as smartphones and computers and the availability of free apps is equally within the expertise of the community practitioner as it is for staff in a specialist clinic. Some of this practical advice would also be appropriate for patients who are temporarily visually impaired, such as those being referred for cataract surgery.
Equipment Required for Low-Vision Work
In fact, there is very little specialist equipment required to carry out low vision assessments, much of that required being found in any practice:
- 1.
Mobile distance visual acuity charts, preferably ETDRS (Early Treatment of Diabetic Retinopathy Study) format ( Fig. 3.4 A ). Projection charts are not usually appropriate because the contrast is often lower, and it is important that the viewing distance and illumination level on the chart can be altered.
- 2.
Trial frame and trial case lenses, preferably full aperture. A phoropter is not effective as it does not easily allow the adoption of unusual head postures, and the patient’s use of eccentric viewing cannot be seen.
- 3.
A ±1.00 DC cross-cylinder for subjective confirmation of cylindrical correction.
- 4.
Amsler charts, preferably in the form of copies of the recording chart, showing black lines on a white background, to which diagonal lines have been added to produce a larger fixation target. These can be used for the assessment of central scotomata, and to aid in training eccentric viewing.
- 5.
A test of (peak) contrast sensitivity such as the Mars ( Fig. 3.8B ) or Pelli-Robson chart. This is essential in providing full information about the patient’s functional performance. It informs the prescribing of aids for reading, and when acuity in the two eyes is equal, allows the ‘better’ eye to be selected.
- 6.
Reading tests for both adults and children. These must be word (rather than single letter) reading charts: one with unrelated words, such as the Bailey-Lovie ( Fig. 3.12A ), is best in order to avoid guessing by the patient.
- 7.
Tape measure or metre rule to assess and compare working distance, focusing range or depth-of-field.
Additional helpful household and everyday items can be easily and inexpensively sourced:
- 8.
A collection of materials representative of the tasks the patient may wish to perform. These might include: samples of print (magazine, map, book (standard and large print), crosswords and puzzles, newspaper, timetable, food labels and packaging, music, medication); needles and wool/cotton for knitting and sewing; and equipment for DIY (screwdriver, plug, fuse). Different types of pen (fibre-tip vs biro) and paper (dark line vs unlined), and a selection of typoscopes, would allow the patient to experience their effectiveness. All these materials could be collected together in a large tidy box ( Fig. 22.1 ) for use when required.
Fig. 22.1
Appropriate items can be collected in the clinic to assess the task performance of patients during low vision assessments.
- 9.
An adjustable-position LED lamp to demonstrate the effectiveness of increased illuminance.
- 10.
A simple demonstration of the effective use of luminance contrast, such as rice in a dark bowl, rather than a light one ( Fig. 22.2 ).
Fig. 22.2
The use of rice and sunflower seeds to demonstrate how containers can be chosen to increase luminance contrast and improve visibility: the rice is much more visible in the black bowl than in the cream bowl.
Other more specialised items demonstrating sensory substitution could be added if the opportunity arose, and these might include: signature guides and writing frames; ‘Bump-ons’ to show how domestic appliances might be marked; a liquid level indicator; and a talking watch or scales. It is also helpful for the practitioner to have various apps and accessibility settings installed on their smartphone or tablet computer for demonstration.
Selecting a Stock of Magnifiers
Whilst a comprehensive selection of all the LVAs available in the UK would certainly cost several thousand pounds, the majority of patients can be helped with a much more modest collection. The results of surveys in several clinics have suggested that custom-made spectacle-mounted devices are rarely used, even in specialist low vision centres, and the majority of aids recommended and dispensed are simple hand and stand magnifiers, including illuminated devices ( ).
There are, of course, major differences between practitioners and clinics in their individual prescribing preferences, but this is quite acceptable, providing that the strategy adopted fulfils the patient’s requirements. The type of aid is less important than the patient being confident with the way it is to be used: nonetheless, it seems logical to prescribe simple aids where possible because they are easier to use and less expensive. The range of aids prescribed will also vary with the patient group being seen: distance telescopes were the second most common aid prescribed by in a clinic with a significant number of young adult patients.
Even if the majority of patients could be helped by simple hand and stand magnifiers and spectacle prescriptions, this could still involve a large number of magnifiers being stocked if every possible power is to be covered. Most patients, however, can be helped using a relatively limited range of magnifications. reported that the most common magnification prescribed is 2×, with around 70% of patients requiring 4× or less. prescribed aids with a magnification range of 1.5× to 20×, but the median was 3×.
Bearing this in mind, an appropriate range of magnifiers in practice would be:
- 1.
A selection of nonilluminated hand magnifiers (such as the Coil 2.3×, and 3×), along with a compact folding lens which is very useful for carrying around in a pocket or handbag (such as the Eschenbach 3.5×) or can be worn on a neck-cord (Eschenbach 4×) ( Fig. 22.3 ). Illuminated pocket magnifiers are useful because lighting is often unpredictable outside the home: for example, the Schweizer range (e.g. +8.00 DS, +12.00 DS, +16.00 DS) ( Fig. 22.4 ), the Eschenbach 3× and 4× Easypocket folding illuminated magnifier.
