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 Investigate the two types of sight defect- long-sightedness and short sightedness.

Find the following information:

1. What causes the defect
   Short-sightedness
   -tends to run in families
   -certain diseases or drugs (type 2 diabetes)

   Long-sightedness
   The exact causes of long-sightedness are not well understood. It is known that the eyeballs of long-sighted people tend to be smaller than average, with less curved corneas – the main optical component of the eye. There may also be a hereditary component, as the children of long-sighted parents can be long-sighted.
   

2. Yhe symptoms displayed
   Short-Sightedness
   Short-Sightedness causes distant objects to appear blurry and unfocused, while nearby objects remain in focus.
   
   Long-sightedness
   Children

   • red, or tearful, eyes,

   • they squint when looking at close objects,

   • they complain that their eyes feel tired,

   • they blink more than normal, and

   • they seem reluctant to, or have problems with, reading.

   Adults
    

   • objects that are close appear out of focus,

   • you find you have to squint to see clearly,

   • your eyes feel uncomfortable after an activity that involves close focusing, such as reading, writing, or working on a computer, and

   • you experience pain or burning in or around your eye.

3. Propose what sort of lens may be used to correct each vision.
   Short-Sightedness
   Short-sightedness can usually be corrected by wearing glasses or contact lenses. Some people wear contact lenses, but others feel more comfortable in glasses. Your optometrist will discuss with you what options are available.
   Contact lenses tend to be more expensive than glasses, and you have to be comfortable touching your eyes to use them. They need to be kept clean and some types require a lot of care. A popular type of modern contact lens is the daily disposable contact lenses, which are worn for one day and then thrown away. When you wake up the next morning you put in a brand new pair. There is no cleaning or storing with these lenses.
   Glasses are usually recommended for children. They are also easier than contact lenses for older people. Glasses are also a better option for those people who find contact lenses fiddly and don’t like touching their eyes.

   Long-sightedness
   Glasses and contact lenses are the most common method used to correct most refractive errors, including long-sightedness. The lenses in glasses converge the light rays, moving the focus back onto the retina.

   Young people who are slightly long-sighted generally do not have problems. If they do, they may need glasses for close work such as reading and using computers.

   Older people, or young people with significant long-sightedness, often have problems because focusing requires a lot of effort. Their vision is more likely to be blurred, especially for close objects, and they usually need glasses for reading and sometimes for distance vision.

   For people with significant long-sightedness, contact lenses can be the best form of correction as they provide better vision and are preferable to wearing thick glasses. Contact lenses can be made from different materials and can be disposable or non-disposable.

    

    

   -http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Eye_problems_long-sightedness?open

   -http://hcd2.bupa.co.uk/fact_sheets/html/myopia.html

   -http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=532&sectionId=10  

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