contact lenses were thought of as early as 1508 when leonardo da vinci sketched and described...
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Contact lenses were thought of as early as 1508 when Leonardo da Vinci sketched and described several forms of them.
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Contact lenses are a changing area of optometry with new lenses being constantly developed
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Refractive errors are corrected by contact lenses, which are placed directly on the cornea
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Lid margin
iriscornea
conjunctiva
sclera
pupil
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Normal focus
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Short sightedness(Myopia)
• Distance vision blurry, near usually OK.
Short-sightedfocus
Short-sightedcorrection
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Long-sightedness(Hyperopia)
• Difficulty seeing clearly and comfortably up close.
Long-sightedfocus
Long-sightedcorrection
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Astigmatism• Irregular curvature of the eye (shaped more like a football than a basketball)• Light in different planes focuses at different points
A
B90
180
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There are many types of contact lenses
RGP lenses
Soft lenses
Disposable or non-disposable
Coloured or clear
Spherical or toric
Extended wear
Multifocal
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RGP lenses (rigid gas permeable)
Smaller than size of cornea
May be less comfortable than soft lenses initially
Very effective in correcting
astigmatism
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RGP contact lens
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Soft lenses
Most commonly used (90%)
Made from hydrogel plastic material containing water
Are 1-2mm larger than cornea
Easy to adapt to
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Soft contact lens
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Spherical lenses
Correct short or long-sightedness
Cheapest, most comfortable lenses
Easy to get in disposable form
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Toric lenses
Correct astigmatism
Lens is specially weighted to
conform to irregular cornea
More expensive than spherical
Some are available in disposable
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Disposable lenses
Daily, two-weekly or monthly replacement
Very simple cleaning (no cleaning for daily)
Latest designs and materials
Very popular
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Coloured lenses
Handling tint Useful when inserting or removing
Enhancing tint Makes light coloured eyes more vivid
Opaque tint Can change brown eyes to blue
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Extended wear lenses
New technology
Made from silicone material which transmits oxygen well
Can wear for up to thirty days without removing
Will not suit all people – your optometrist will advise
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Multifocal contact lenses
Can wear one reading lens, one distance
Can have dual focus lenses
New technology – slightly more
expensive
Available as a disposable lens
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Advantages of contact lenses over glasses
Better field of view
No fogging up
No one has to know you have refractive error
No frames – eg, useful for sport
Sometimes the vision is better
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Hygiene is extremely important with contact lenses
Always wash your hands before touching lenses
If lenses are not clean, bacteria can stick to them
A tiny scratch on the eye can get infected
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If you have a sore, red eye take your lenses out and go to see your optometrist ASAP
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If properly looked after, the chance of having an infection with contact lenses is extremely low
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Consultations for contact lenses Contact lenses need to be fitted to
each individual eye
Several tests are required for: measuring and trying the lenses
teaching insertion and removal
after care
Your optometrist can advise you about the tests are required
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Optometrists
Detect and diagnose problems with eye health
Prescribe glasses or contact lenses, if required
Diagnose and treat problems with focusing
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Optometrists
Are university educated and regularly undertake continuing professional education
No referral is required
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To find an optometrist
Yellow pages
NZ Association of Optometristswww.nzao.co.nz0800 439 322