There was an excellent response to this exercise which suggested that not only are most readers familiar with patients with hearing impairment, but recognise its significance upon the lives of sufferers.
You were asked about the following case:
An elderly patient (82 years of age) has been diagnosed as having longstanding atrophic (dry) age-related macular degeneration. They are pseudophakic. They have rheumatoid arthritis but otherwise claim full health. They achieve a distance acuity as follows;
R +0.50/-0.50 x 175 (0.8)
L +0.75/-0.75 x 180 (0.84)
Pinhole reduces acuity
With a +4.00DS addition, they manage N 24 at 25cm
Their main demand is to be able to read the Guardian again – they have this as an electronic subscription and read it on their tablet (a gift from their son). They would also like to be able to read other magazines and books and do not like audio books (they are quite definite about this).
What would be your first choice of magnifying appliance to try? Explain why this might be appropriate and what possible challenges use of the appliance might present. In your answer, please give specific details (lens power, details of the appliance, how it is to be used and so on).
Key points
First, there are a number of key points to remember when deciding on a management plan.
- As a keen reader, an acuity reserve would be advisable. They can achieve N24 with unit magnification (+4.00 addition) and have negligible distance refraction. If we take N8 as appropriate for magazine, N4 as a target acuity would offer a reserve of 2:1.
- The patient is arthritic so might struggle with a hand magnifier for any length of time.
- He has access to a tablet and electronic newspaper.
- He likes magazines, some of which might be glossy and reflective.
Discussions
Most respondents were happy with the concept of an acuity reserve. Here is an example. ‘Allowing for acuity reserve of 2:1 the theoretical magnification for prolonged reading is 6x. However, a lower magnification may be easier to use and may be better tolerated especially if reading is in shorter bursts. Spectacle magnifiers (high additions) would create an unacceptably short working distance for a larger newspaper so a hand or stand magnifier will be more appropriate. Our first choice would be an internally illuminated stand magnifier for good illumination and ease of use (figure 1). This ensures they maintain correct distance between paper and lens. I would try with 4x mag initially (but with an expectation to increase this to 6x if for prolonged use to allow for acuity reserve).’
Another wrote, ‘I would ensure an acuity reserve for prolonged reading so suggest something likely to allow them to see down to N4 (so that N8 is easily achieved). N4 is six times smaller than N24. A reading addition might be possible but, as this would likely be +24.00D, the working distance of just 4cm would prove prohibitive.
A 6x hand magnifier might work but would be cumbersome for the arthritic patient. I suggest a 7x stand magnifier (24D lens) with internal LED illumination for use with any current reading spectacles and at a more reasonable working distance. I would also suggest a reading stand to help support the newspaper upon when using the magnifier.’
Indeed, the short working distance for spectacle magnifiers would be likely to hinder successful use by someone with late acquired sight loss, used to a longer working distance for many years. That said, they should never be totally ruled out as they do offer the best field of view which, for some people, is preferable. It helps, for example, to find the start of the next line when reading block text as in books and newspapers.
A respondent from South Africa wrote, ‘The acuity converted into a reading Rx which requires the px to move the reading print 3x closer (to achieve N8). If the client wishes to read 20/20 (sic) then +16.00 would be required.’
Figure 2: A modern near spectacle-mounted telescopic device
They then suggested a lesser magnification to see how the patient performed. ‘Specs at 20/40 (+8.00D) with 10prism base in both eyes should be assessed with an approximate working distance of 12.5cm.’ I agree that this is worth trying, especially where the patient is very keen on spectacles as an option, but it is likely they will prefer the stand magnifier. Fair point though.
A number of you suggested spectacle mounted near telescopes as an option (figure 2). For example, ‘The most appropriate aid for this patient would be spectacle mounted near telescopes. As the patient suffers from arthritis, a hand-held magnifier would prove difficult to handle, and a stand magnifier would be difficult to use in conjunction with a tablet.
While appreciating that a near telescope can be difficult to use at first, and the patient would need some training, I do not feel this would be too much of an issue here as the patient is obviously reasonably intelligent as she reads the Guardian.
This system would maintain binocular near vision and would be comfortable for the patient to use. The tablet could be placed on a fixed surface, and the patient would be able to set a comfortable working distance. Guidance would be used on satisfactory lighting behind the patient, and this should be done on a home visit to the patient.
The estimated task acuity is N8, therefore the target acuity with magnification is N4, assuming acuity reserve of 2:1. N24 is six times bigger than N4, so six times the magnification, a +24 add. This would produce problems with the weight of the aid, but within the available range.’ Many modern spectacle-mounted near telescopes are quite comfortable to wear, but typically offer two to three times magnification. For use with the tablet, however, enlargement of the screen font might allow adequate reading.
A reassuring number of you moved into the ever-important world of electronic magnification. For example, ‘We worked out that 6X magnification was needed for this gentleman and that a 24D spectacle prescription would not be appropriate.
We were torn between a 6x hand magnifier, 6x stand magnifier or a mouse device which displayed images on the television. The hand magnifier was then ruled out due to the need to keep the required distance from the object. We would probably give him a trial of the mouse at home first and, if he was unable to use it, then let him try a stand magnifier.’
Another suggested, ‘The best optical appliance for this patient is the desktop CCTV. A CCTV device like a computer mouse is put on the reading material, it is moved slowly along the text and it is observed on the desktop screen. Since the patient is in fairly good heath this should be easy to do. You need a large flat surface to use this device.
The advantage of this device is that it gives a wide field of view, therefore it makes it easy to read newspapers, books and magazines for a long period of time. The magnification can be varied, it can go up to 75X. The magnification can be varied to suit the patient. Contrast can be altered to make reading easier. This device uses binocular viewing, therefore making it easier to use.
The patient can use reading spectacles with the CCTV reader with an antireflection on the spectacle lens which will help with the reflections from the screen. The CCTV reader will give the patient a larger field of view compared to a near vision telescope and handheld magnifier.
The working distance with a CCTV reader is much longer, compared to a handheld magnifier of strong magnification. The speed of reading with a CCTV device is much faster compared with a handheld magnifier. The disadvantage of this device is that it is expensive to buy, needs a large surface to use, and is not portable.’