What is low vision?
Low vision describes a loss of vision that cannot be corrected with regular glasses, contact lenses, medicine, or surgery.  A person with low vision can find it hard to see things clearly making it difficult to carry out everyday tasks.

What causes low vision?
Low vision most commonly happens as a result of the eye changing with age.  People can also develop low vision because of eye diseases and health conditions such as Age-Related Macular Degeneration, Cataracts, Glaucoma and Diabetic Retinopathy.

How can I tell if I have low vision?
Low vision is usually first noticed as a reduction in the sharpness of definition, with difficulty coping when lighting is poor.

How many people have low vision?
There is a total estimated population for people aged over 65 of 2,000,000 or 1 in 5 with a sight loss that significantly affects their daily life. (Source statistics from RNIB website using figures from the Analysis of Medical Research Council data, the Office for National Statistics and the Analysis of National Diet and Nutrition Study data.
References:
ONS – Office for National Statistics.
MRC – Analysis of Medical Research Council data as reported by Evans J, Fletcher AE, Wormald R, Ng ESW, Stirling S, Smeeth L, Nunes M, Breeze E, Bulpitt CJ, Jones D, Tulloch A. (2002).
NDNS – Analysis of National Diet and Nutrition Study data as reported by van der Pols JC, Bates C, McGraw PV, Thompson JR, Reacher M, Prentice A, Finch S (2000).

What are low vision aids?
Devices, either optical (magnifiers) or non-optical (lighting and electronic systems) that can be used to improve the quality of vision.

There are low vision aids which can help you to do lots of useful things close-up, like reading or seeing control buttons on a cooker.  There are also other low vision aids which can also be useful for seeing things which are far away, like road signs or looking at a view.

Where do I get low vision aids?
An optometrist or low vision specialist can evaluate the degree and type of vision loss you have, and advise on the appropriate low vision aids such as magnifiers, telescopes and video magnifiers, which will help your vision.  Some vision aids will be available from your local low vision service so that you can try them at home.  The types of aid available will depend on the product range held by the particular clinic.  Vision Enhancers Ltd is able to provide a full collection of optical vision aid products together with guidance to help you in choosing and using devices to meet your specific vision aid needs.

What is Age-related Macular Degeneration?
Age-related Macular Degeneration is an eye disease that results in a loss of central vision leaving only side or peripheral vision intact.  Age-related Macular Degeneration (AMD) is the leading cause of vision loss in older people.  Macular degeneration affecting younger people is called “macular dystrophy” and can run in families.

There are two types of AMD, dry and wet and both can lead to severe vision loss.  AMD affects the macula, the small central part of the retina responsible for central and detailed vision.  It is not painful but cells in the macula break down causing this loss of central vision.

What is Glaucoma?
An eye disease, related to high pressure inside the eye that damages the optic nerve and leads to vision loss. Glaucoma affects peripheral, or side, vision.  The optic nerve carries information from the retina, the light sensitive layer in the eye, to the brain which it sees as a picture.  Progressive damage to the optic nerve from a build-up of pressure inside the eye due to ineffective or blocked drainage channels can be detected through eye examinations and special tests.

What is Diabetic Retinopathy?
Diabetes is a chronic disease related to high blood sugar that may lead to vision loss as well as other systemic effects. Diabetic Retinopathy can be one of the complications of advanced or long-term diabetes.  It affects the network of blood vessels lying within the retina which can leak and damage the entire retina including the macula. The vessels may leak blood and fluid in the early stages and can result in blocked vessels in later stages which means new weaker blood vessels will grow in the eye.  These new vessels can grow in the wrong place and can leak and cause scarring which can pull and distort the retina and can lead to retinal detachment.  Most sight loss due to diabetes can be prevented but early diagnosis is vital which is why Diabetes patients should have an annual eye examination.

What are Cataracts?
A Cataract is a clouding of the lens that reduces the clarity of the vision so that people see through a haze and there may be an increase in sensitivity to glare so that halo’s appear around bright lights. There may also be a loss of contrast and trouble distinguishing colours as the lens becomes more yellow with age e.g. it may be difficult to tell the difference between similar colours such as navy, blue and black.  In advanced stages it can be harder to read as the printed letters can appear faded and not as distinct. In a usually safe and successful short operation, the cloudy lens can be replaced with a plastic lens to remove the symptoms. Cataract surgery has a high success rate in normal eyes.

What is absorption for colour filters?
Filters absorb the short wave, high-energy ultraviolet and blue elements of the light so enhancing contrast and reducing photosensitivity. Filter colours differ depending on the absorption range, which is how much ultra violet light is filtered out. The higher the number the more UV light is absorbed by the filter and the less light is transmitted through to the eye.  

What does polarising mean for colour filters?
A polarising filter allows light to enter the lens of the eye in a specific direction whilst absorbing other light.  Its effect is to remove reflections from a shiny surface. 

What does the notation on telescopes and binoculars mean?
The first number in the notation refers to the optical magnification and the second to the size of the aperture or opening of the telescope or binoculars.  As an example a 4x 12 telescope such as the Eschenbach Kenmax Near Focus Telescope 4x 12 would provide a 4x magnification with an aperture or opening of 12mm.