What is Low Vision?
Low vision is reduced central and/or peripheral vision that cannot be improved by normal spectacles, surgery or medication. It can affect a patient’s ability and/or mobility to perform everyday tasks.
What causes Low Vision?
Low vision is caused by a variety of reasons. The commonest are Age-Related Macular Degeneration (wear and tear at the back of the Eye); Diabetic Eye Disease (bleeding/oedema within the eye); Glaucoma (pressure inside the eye) and Cataract (clouding of the middle of the eye).
What can be done to help?
Each person is given a low-vision assessment, as outlined below;
1. An eye examination using specialised equipment.
2. A questionnaire to identify the person’s history, symptoms, needs and objectives.
3. A demonstration of hand held, stand, spectacle mounted, electronic and non-optical low vision aids is performed as appropriate.
4. Any Low Vision Aids required are provided on loan for a trial period followed by a review appointment.
5. Low Vision Aids which are deemed satisfactory are supplied following adaptation.
What is magnification?
Low Vision Aids come in a variety of designs and magnification as discussed later. In general the lower the magnification the greater the depth of field and field of view.
The depth of field is the amount a magnifier can be moved from the print and still produce a range of clear vision. The field of view is the area of side vision that is apparent looking through the magnifier.
Distortion and spherical aberration are the main defects that can occur in magnifiers and aspheric lens designs/anti-reflection coatings are used to reduce these unwanted effects.
Hand Held magnifiers
These are relatively easy to use and are portable allowing tasks such as reading prices in shops, viewing clocks, bus numbers, etc. However they require steady hands and manual dexterity to adjust the focus.
These generally have a fixed focus and can be less tiresome. These are popular for general reading and can be adapted for writing cheques, etc. However, they are less portable and some require illumination.
Spectacle mounted magnifiers
These come in a variety of forms such as telescopes, bifocals, Aspheric Lenses; etc. They are hands free and can be used for many tasks such as watching T.V., playing musical instruments, hobies such as knitting, bridge, etc. They can however take some time to get used to.
There are many variations of electronic magnifiers, from computers with speech recognition and magnified text to portable
CCTVs which can be either stand alone or plug into your existing TV. Other spectacle mounted devices can be used to view outside objects using auto-focus cameras.
Correct illumination is very important for the majority of low vision patients. This is usually achieved through angle poise PLS lamps or self-illuminated magnifiers. Glare can also be a problem and can be reduced through tints, wrap around filters or specially coloured lenses which change due to the amount of available light.
A vast array of other non-optical aids for around the house are available such as speaking clocks, reading books etc.
There are now a variety of over 20 Apps to help patients use technology to read, navigate communicate with sighted helpers and to chat on social media.
Where necessary the following services can also be discussed mobility training, eccentric viewing trains (to use your side vision), technology to read using artificial intelligence such as Orcam, support groups for specific eye diseases, specialist tints to reduce glare, bioptic telescopes to allow hands free distance and near viewing.
What costs are involved?
An initial consultation lasts one hour with subsequent reviews 1/2 hourly. Consultation Fees are invoiced separately and can be redeemed from BUPA and Norwich Union. Only Low Vision Aids that are deemed satisfactory are invoiced and any loan models are returned at no charge.
What are the advantages of this clinic?
1. We keep over 350 types of Low Vision Aids in stock and are constantly assessing new models.
2. In general, the majority of complicated Low Vision Aids are not available in the NHS.
3. There can be a considerable waiting time and little or no ability to review low vision aids given on the NHS.
4. Dr Mackie holds a post-graduate qualification and is a Visiting Lecturer in Low Vision at Glasgow Caledonian University.