Why is it more difficult for me to see at night?
When it gets dark, our pupils dilate and this makes everyone more short-sighted. This is usually why night-time vision is worse than during the day even if you are wearing your up-to-date prescription. Should you be driving at night, more care should be taken on the roads, as oncoming headlamp glare can be quite distracting. Any prescription found for general use should obviously be worn in these conditions. Some inherited conditions of the eye like retinitis pigmentosa also cause problems with night vision.
 
Can my contact lenses get 'lost' behind my eyeball?
No, this can NEVER happen as the eyeball has a 'safety net' situated underneath both eyelids. This 'safety net' is a membrane called the conjunctiva. The conjunctiva is a continuous membrane enveloping the outer portion of the eyeball as well.
 
Will my sight worsen if I start wearing specs or contact lenses?
Wearing a prescription does not make your vision worse. Often when someone gets spectacles for the first time the visual improvement is so amazing that vision without them seems much worse, especially as time goes by. However, this is simply because the brain can now compare two images directly: one with specs and one without.
 
What are the advantages of glass lenses over plastic lenses?
Plastic lenses are lighter and have 3 x the impact resistance of glass while glass lenses are thinner.
 
Something is definitely not right about my new specs - what do I do?

Perhaps you are aware that your specs are not right even after trying them for 3 weeks. Before booking a retest with the Optometrist, you should do the following:

  • Step One: Visit our Spectacle Collections team bringing in your new specs as well as any old specs if you feel that they seem better.
  • Step Two: Our team will check your new spectacles to ensure that all the measurements required are correct and as per the optometrist's specification. Any errors found will be rectified instantly, if this is possible.
  • Step Three: Assuming the measurements are correct, our team will then recheck your frame adjustment to ensure that they fit your face in a visually optimal way.
  • Step Four: At this stage you may already feel better and simply need to readapt to the new fitting. If you still feel uncertain and suspect the prescription to be at fault, then you would be advised to see your optometrist for a reassessment. It is generally better to see the same optometrist that consulted you initially, so an appointment may be required should that optometrist not be present on that day.
 
 
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There are 16 entries in the glossary.
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Term Definition
20/20 VisionThis is also known as perfect sight where no prescription is required in order to see things clearly and comfortably. The fraction 20/20 is understood as follows: the bottom half represents the distance in meters at which a perfect sighted person is able to see clearly a target seen by another at 20 feet. So if you are perfect sighted you will see at 20 feet exactly what another perfect sighted person will see at 20 feet. However, if you have trouble seeing things in the distance, you might see at 20 feet what a perfect sighted person sees at 40 feet. So this means your vision is measured as 20/40.

Assuming you have perfect sight then when you are looking at something in the distance, light from the object will focus on your retinas very precisely. When seeing something close-up the focusing is blurred very momentarily, but this is unnoticeable because your eye has an automatic refocusing ability that makes the target clear. This refocusing ability is called 'Accommodation' and it works by making the natural lens of the eye fatter, or more convex in shape. As we get older we lose more and more of this ability, which is why things close-up start to blur after about 45 years of plodding on the planet. 

Short-sightedness means that the light focuses in front of your retinas or 'too short' and long-sightedness means it focuses 'behind' or 'too long'
 


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