Instruction in Near Low Vision Aid Use

The patient should be advised:

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  how to position the magnifier and the task material: for example, showing the patient to see that the shorter the eye-to-magnifier distance the greater the field-of-view ( Fig. 20.1 ) and how the lighting should be arranged. Demonstrate how to locate the optimum focal distance with a hand magnifier ( Fig. 20.2 ): with the magnifier touching the page there is no magnification, but it increases as the magnifier moves away, to reach a maximum when the object is at the focal point: move the magnifier further away and the image distorts;

  
  

  
  

  
  

  

  
  

  
  

  Demonstrating that field of view increases as the magnifier is brought closer to the eye.

  
  

  
  

  
  

  

  
  

  
  

  Demonstrating the effect of task distance on magnification: no magnification is given with the magnifier flat on the page; it must be slowly raised to where the object is at the focal point and magnification is optimal.

  
  
  
  
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  which spectacles (if any) should be worn with the magnifier;

  
  
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  the location of the on/off switch and other controls, if present; and

  
  
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  how to change the batteries, if relevant.

Instruction in Distance Low Vision Aid Use

Distance low vision aids can be less intuitive to use than near magnifiers, so more detailed instruction is likely to be needed (and perhaps training, see Section ‘Training for Distance Vision Aids’ later).

The patient should be advised:

• 1.
  

  How the aid is mounted (spectacle-mounted; permanently or clip-on), or how carried (wrist or neck strap).

  
  
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  Which end goes towards the eye. Often the device will have a rubber cup around the eyepiece, so the patient should learn that the ‘squishy end’ goes towards the eye.

  
  
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  Whether to use the aid with the distance spectacles. If it is to be used as an outdoor spotting aid, this must be with the spectacles if worn: for such an intermittent task, the patient cannot keep taking their spectacles off. For longer tasks, such as watching theatre performances or cricket matches, it will depend on whether the patient has significant astigmatism.

  
  
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  In the case of a monocular device, what to do with the nonviewing eye? Can it be ignored and suppressed, or must it be covered? It is often easier to hold the aid with the hand on the same side of the body as the eye being used. If the hand on the opposite side is used, however, this can sometimes be placed up to the eyes in such a way that it acts as an occluder for the unused eye.

  
  
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  How to position the aid to minimise device movement. The supporting arm can be braced against the upper body, or the elbow cupped in the opposite palm. If sitting, the elbow can be supported on a table or chair arm. Explain that any tremor of the aid will lead to magnified image motion, which must be avoided if optimum performance is to be obtained.

  
  
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  How the aid should be positioned as close to the eye (or spectacles) as possible to increase field-of-view. To achieve this, the thumb and first finger can be placed in a ring around the eyepiece, and these are then held against the bones of the orbit to steady it. With practice the patient may be dextrous enough to focus the telescope with the middle, ring or little fingers of the same hand. This should not be practised at too early a stage, because the focusing mechanism of new telescopes is often rather stiff and it may need two hands to carry out fine manipulation until the mechanism becomes smoother. It can be helpful to have the telescope looped around the neck on a cord, just in case it is dropped. Show the focusing range of the telescope, showing how a minimum separation of the component lenses produces optimal focus for long distance, whilst the longest telescope length corresponds with the closest viewing distance.

Training for Near Optical Low Vision Aids

Training is best performed when the patient is comfortable and in a home-like environment. The ideal set up would include an office desk and chair, a table and dining chair, a kitchen surface and an armchair. Various light sources should be available including task lights, desk lights, and a reading lamp. Nonoptical aids such as rulers and typoscopes should be kept in the same area, along with needle-threaders, felt or fibre-tip pens, writing frames and samples of large print.

A variety of reading tests and real-world reading material should be available, including menus, magazines, books, letters, food packets and medicine labels, as well as intermediate tasks such as music, sewing, jigsaws, DIY equipment, playing cards and a computer screen.

The exact format of the training programme will vary for each individual patient and trainer and may be very informal in some cases. A comprehensive device training routine would follow the following stages (adapted from ):

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  Observe the patient to determine any physical difficulties and limitations in the use of the low vision aid.

  
  
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  Review the objectives to be achieved by use of the aid and remind the patient of related tasks which the aid is definitely not suitable for. Point out the advantages and disadvantages of the aid (e.g. ‘it allows you to see your knitting, but you need to hold it closer than you did before’).

  
  
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  Review other strategies which will be used with the device, such as eccentric viewing and steady eye strategy.

  
  
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  Discuss the successes and problems revealed when the patient first used the aid during the initial assessment (e.g. ‘You were able to read very small print but found it difficult to find the beginning of each new line’).

  
  
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  Assess performance with the aid. Measure the patient’s present performance: for reading, a timed test will be useful to act as a baseline standard.

  
  
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  Review the positioning of the aid.

  
  
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  Determine the best physical setting. Discuss lighting, posture and appropriate seating (with or without a table or work surface on which to lean), and the best way to hold and support the magnifier and the task (perhaps considering a reading stand, clipboard, or double-ended clamp for the magnifier). Decide if nonoptical aids might help, such as fibre-tip pens and a writing frame, or a typoscope for reading.

  
  
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  Assess the individual skill elements which go to make up the task. Ask the patient to perform the task, breaking it down into its component sections and assessing whether each of these individually is optimally performed. For example, for reading individual skill elements would be to spot and localise the area of interest (the beginning of the first line on the page, the headline of an article) within the task area, to track along the full line of text right to the end (but to realise where the blank spaces are between columns), to return to the start of the next line without repeating or missing a line, and to appreciate when the end of the article/page has been reached.

  
  
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  Practise based on revealed weaknesses. Particular practice tasks can be devised which can be performed repetitively to allow the patient to improve that skill. For example, if the patient struggles to find the start of each line, they can be asked to follow a zig-zag pattern by tracing each line back and then going to the next line down. The patient should also be given the opportunity to demonstrate and reinforce their strengths so as not to become anxious by concentrating only on what they cannot do.

  
  
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  Repeat assessment of performance. This would be a repeat of the assessment which was carried out in step 5 above, to measure any improvement. This can be very motivating to the patient and demonstrates the importance of practice.

  
  
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  Review the patient’s understanding of how the aid(s) are to be used.

  
  
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  Evaluate the patient’s feelings about how successful the aid is in relation to the required aims. Demonstrate how much their performance has improved during the training session. Remind them how difficult these tasks were previously and reassure them they can expect further improvement with continued practice. Daily practice with aids is known to be associated with optimal performance but the patient may decide that this effort is not worth the potential gain: they may, for example, have set the goal of reading novels, but decide that it is always going to be challenging to read with a magnifier no matter how much practice they do, and choose to use talking books instead.

  
  
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  Encourage the patient to practice at home, give them written instructions if appropriate. Reassure them that it is normal to become tired or frustrated when first using a magnifier, and that it may feel like they are ‘learning to read again’. Frequent short practice sessions are generally preferred.

  
  
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  Plan the next training session, perhaps in one or two weeks. Give an indication of how many more visits are likely to be needed, how long each visit will last, and what the final goal is at the end of this series of visits.

Training for Distance Vision Aids

Training is more likely to be required for distance vision aids such as monocular telescopes. The devices themselves are more complex, and the concept of focusing can be challenging for people with longstanding visual impairment. Devices are likely to be used in settings which are more crowded: for example, finding a platform indicator board in a large railway station is a visually demanding task. They are more likely to be used outside, with variations in lighting and contrast, and whilst the user is standing. They are also more dangerous to use: if someone tries to walk when using spectacle-mounted distance telescopes they are likely to fall; if they look at the sun with a telescope they may develop severe retinal disease.

It is useful to demonstrate the device indoors (first sitting, and then standing) before moving to an outside training session.

Equipment which can help the patient use a telescopic device includes a brightly coloured ball (for tracking moving targets), hollow cardboard tubes (for practising lining up the telescope with the object of interest) and even a slide projector to demonstrate the concept of ‘focusing’ an image.

A complete training package will mirror that offered for near low vision aids earlier. Specific additional skills for telescope use are localisation, focusing, spotting, tracing, tracking and scanning. Unlike the skills involved in reading, none of these are familiar skills to the patient, as they are skills related to the aid rather than to the task to be performed. It is likely that all patients will need at least some instruction to make the best use of the device.

Localisation involves lifting the telescope into position as quickly and accurately as possible, so that the object can be seen. This can be most readily achieved with a single bright object against an uncluttered background, such as a torch light in a darkened room. This can then progress to aligning the telescope to view the instructor, where auditory cues can also be used to assist. Patients often find the task difficult because as they move the telescope to their eye they drop their gaze to it. On the contrary, the patient should keep fixating all the time on the distant object of interest, and interpose the telescope along their line of sight. A lower-powered telescope with wider field-of-view could be substituted temporarily for training purposes, or the patient could practice whilst viewing through hollow cardboard tubes.

Initially the patient may find it easier with the nonviewing eye covered, but should progress to having both eyes open, and ignoring the unmagnified view from the nonviewing eye. It can sometimes be arranged that the view of this eye is obscured by placing the hand holding the telescope across in front of it.

As the patient becomes more skilful, several objects can be placed together, and the patient is instructed to align the telescope to view just one of them: to accomplish this they must lift the telescope to their eye, and then move in precise fashion between the various objects to find the one required.

Focusing involves the subject exploring the whole range of image distances for which a clear image can be arranged. The instructor positions the target at a variety of distances and encourages the patient to refocus the telescope each time. A guide to whether this is being done correctly can be obtained from the visual acuity (because letters of half the size could be read at half the distance) and from the clinician viewing through the telescope to check the clarity of vision. If in doubt, the concept of focus may need to be explained by blurring and clearing a target on a slide projector.

Spotting combines localisation and focusing skills: the distant object is seen without the telescope, then the telescope is raised so it is aligned between the eye and the object and focuses the telescope to view the target. Brightly coloured shapes stuck onto a plain white wall can be used, and if numbers are written on the shapes, these will monitor the accuracy of focusing. As the patient’s skill increases, the shapes and numbers can be made smaller. Photographs from magazines, cut out and placed against the plain background, can be used to test the patient’s ability to interpret the magnified image.

Tracing involves following a stationary line in the environment, such as the edge of a shelf or a line drawn on a wall. A similar task which also involves refocusing of the telescope can be set by laying coloured tape or rope across the floor or table-top in a random way. Along its length (at progressively increasing distances from the patient) cards containing written words are placed: the subject must trace along the rope, constantly altering the focus of the aid in order to read the cards.

Tracking is the same principle using a moving object. For example, the instructor walks around the room carrying a picture which can be moved side-to-side or vertically or rolls a coloured ball across the floor. The patient will need to learn to move their head smoothly at the same speed as the object they are watching (and may need to practice this without a telescope first of all). If the object moves towards the patient, they will need to constantly refocus as well as track the object.

Scanning is the most difficult skill to learn. This involves searching the environment for an object which cannot be seen without the telescope: in previous spotting tasks, the object could be seen without the telescope, although its fine detail was indistinguishable. An orderly sequence of overlapping horizontal sweeps of the telescope must be used to systematically search the designated area. In early training the area should be defined by a clearly seen border (black lines on a wall), with a small picture placed within the boundary. The time taken to locate and identify the picture can be recorded. Alternatively, an object could be placed on a large table-top, and the patient scans to locate and identify it.

Application to everyday tasks is the ultimate aim and will involve elements of all the skills practised. They are usually outdoor rather than indoor requirements, and it can be useful to train outdoors because it gives the realism of the ‘uncontrolled’ environment of different colours and luminance with randomly moving targets. Each task should be discussed with the patient to decide how it might best be performed. For example, in looking for the number of an approaching bus, it is difficult to both align and focus the telescope within the limited time available. A more effective technique is to focus the telescope in advance, using a lamp-post, street sign or shop frontage which the bus will pass. When the bus is seen approaching, a sweep of the telescope across the visual field should allow the destination board to be seen. The motion of the telescope must then be matched to the movement of the bus for long enough to allow reading of the sign. Alternatively, if the patient wished, for example, to locate a street sign at the junction of two roads, a knowledge of its likely location could guide the scanning routine. It may well be near to ground level, below the ground floor window, or higher on the wall below the first-floor window. Beginning at ground level, focusing on the building wall, and then using systematic overlapping side-to-side sweeps will allow the clear image of the sign to be found. Mobility instructors will be familiar with the layout of street signs in the relevant borough.

Training for Aids for Increasing Peripheral Field Awareness

A reversed telescope or handheld minifier is used as a spotting aid. To become familiar with this, the patient is first asked to look around the clinic room with the minifier without moving their eyes and to report on what they can see. The instructor can move around the room and ask the patient where they are standing and what they are doing (e.g. waving or standing on one leg). The patient can then move to the end of a corridor and be asked to use their device to find obstacles such as fire extinguishers and litter bins, and to plan their route along the corridor. Training can progress to route planning in complex environments such as railway station concourses, initially when they are quiet, then finally at busy times.

To use sector or peripheral prisms, patients should practise making head movements so they can see the target through the unobstructed (prism-free) portion of the spectacle lens (see Chapter 12 ). Patients adapt quickly to the prism, after only a few minutes ( ). Although hand-eye coordination can be improved further with additional computer-based training ( ), many patients benefit from peripheral prisms with minimal extra training.

Training for Electronic Vision Enhancement Systems

It was previously thought that extensive training was needed to use electronic magnifiers, but a recent randomised controlled trial has shown that there is no benefit from additional training, beyond that provided by the device supplier ( ). This is probably due to improvements in the design of these devices and patients’ increasing familiarity with technology.

Training for Accessibility Settings on Consumer Electronic Devices

Training and support for consumer devices, such as smartphones and tablets, may be offered by rehabilitation workers for visual impairment and by many local sight loss charities: such individuals may be called ‘Digital Inclusion’ specialists. Patients might have tech-savvy relatives who are happy to work through the accessibility settings with them, perhaps using online videos for the specific operating system used. Some device manufacturers have staff trained in supporting people with vision impairment in their shops, and larger shops (such as Apple Stores) run sessions for people with low vision to explore their device settings. However, do not forget that patients may not have even basic technology skills, they may be anxious about using these devices, and they might find environments like an Apple Store quite alien.