Eyecare
Info...







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Refractive Errors...
What is Presbyopia?
Normal healthy young eyes have
a wide range of focus from far distance to a few centimetres. In a young
eye, the lens is very flexible. As we get older, the lens of the eye
thickens and slowly loses its flexibility leading to a gradual decline in
our ability to focus on objects that are close up. This loss of focusing
ability is called PRESBYOPIA. It is not a disease but a normal and
expected change which sooner or later affects everyone, whether they
already wear contact lenses and spectacles or not. It does not occur
suddenly. Around the age of 40-45 we begin to realise that we are holding
the newspaper further away or we need more light to read the telephone
directory.
What should a person do?
Pay a visit to an optometrist. An eye examination, which takes between 20 and 30 minutes,
should be part of a normal health care routine. Not only will the
practitioner measure the focusing defects of people's eyes but will also
check closely for any early signs of eye disease or other medical
condition. As of 1st April 1999 all eye examinations for
patients aged 60 and over are free of charge.
How is Presbyopia
corrected?
The practitioner will advise on
the wide range of options available to restore good vision. It is
important that any hobbies or special tasks at work are mentioned. There
is no advantage in delaying using reading spectacles they will not make
eyes lazy.
Reading glasses
The simplest form of lens - for
correcting near vision - is worn for reading, sewing etc, but will
probably make distance vision blurred. This means that someone may have a
pair of spectacles simply for reading but cannot use them to drive or
watch TV. It will probably be necessary to keep removing them when
speaking to colleagues at work, for example. However, there are several
alternatives that solve this problem.
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Half Eyes: If someone has good
distance vision, they might choose half eyes. These are shallow frames
designed to enable a person to look over the top of the frame when
distance vision is needed. However, this design is a disadvantage if the
near task is above the top of the lens.
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Bifocals: These are special
lenses which are plain (or have prescription for distance vision if
required) in the top half of the lens and a prescription for the near
vision (reading) in the lower half.
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Progressive or Varifocal
Lenses: some people find the dividing line distracting or are concerned
about the appearance of bifocal lenses. Progressive or Varifocal lenses
(some people call them bifocals without lines) solve this. These lenses
progress gradually from distance strength at the top to reading strength
at the bottom, giving a range of focusing strength in between and are
becoming very popular.
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Anti-reflection lenses
Lens reflections can be a
problem for spectacle wearers. There are four different types of
reflection:
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Reflections on the front of the lens, seen by other people |
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Reflections from behind which are superimposed on the wearer's field of
vision |
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Internal reflections caused by the lens thickness, particularly
noticeable in high powered lenses |
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Reflections at the front surface of the eye |
All these reflections can
reduce the amount of light reaching the eye by as much as 15%, which means
both vision quality and contrast are impaired. There is a solution. By
treating the lens with a special coating, reflections can be limited to
less than 1% and the problems almost eliminated. Anti-reflection lenses
give such a dramatic reduction of reflections, the benefits are
significant.
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Clearer and sharper clarity of vision |
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Closer to natural vision |
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Improved driving vision - especially at night |
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Less VDU glare |
In short, everyone who wears
spectacles will enjoy the overall improved visual comfort provided by
anti-reflection coatings.
Contact lenses
For contact lens wearers, there
are various ways a practitioner can help when near focus begins to blur.
There are bifocal or multifocal contact lenses, or it is possible to wear
glasses over contact lenses for reading.
When to visit a
practitioner again
Between the ages of 40 and 65
your prescription is likely to change significantly. It is essential for
this age group to have their eyes examined every two years, not only to
review their prescription, but also to ensure their eyes are healthy.
Remember, the optometrist (or OMP) may also see general health problems
such as high blood pressure or diabetes which, if caught early enough, can
be effectively managed by a doctor.
This
factsheet is designed to give you a very brief introduction
to the subject and has been produced by the Eyecare
Trust. |

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News & What's New
The site was last updated on 1st November 2003.
The latest issue of our newsletter and an overhaul of all areas of
the site
feature in this update.
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Newsletter
Issue 10 (autumn/winter 2003) contains details of the science behind
your glasses, news on the latest optical products and an outline of
some of the causes and treatments for dry eyes.
View current issue >>>
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