Common Eye Disorders

Myopia (nearsighted or short sighted)

This is one of the most common vision disorders. It is the inability to focus on objects at a distance. The light rays are focused at a point in front of the retina, causing a blurring of the image. Myopia is typically caused by continued up close activity which causes the muscles to be in a state of constant contraction causing a lengthening of the eyeball. A person with myopia can see things up close, but they will not be as clear as they would be if the eyes were relaxed as in normal eyesight.

Hyperopia or hypermetropia (long sighted or far sighted)

This is the inability to fucus on objects at a close range. This is caused by tension that sortens the length of the eyeball, therefore becoming to short so that light rays are focused on an area behind the retina.

Astigmatism

Astigmatism is an unevenly shaped cornea, almost like a corrugated iron roof. It can be as a result of uneven tension of the extraocular muscles surrounding the eye. This uneven shape causes light rays to focus unevenly, some in front of and some behind the retina.

Presbyopia

This is commonly referred to as “aging vision”. This is the name given to the hardening of the lens and a tightening of the muscles often associated with aging. This condition occurs in nearly everyone at some point in their life, usually around the age of 40. This inflexibility causes ciliary muscle to be unable to change the shape of the lens.

Taking Care of Your Contact Lenses

Contact lenses are a popular way to correct eyesight, whether short sighted, far sighted, presbyopia, or stigmatic eyes. Contact lenses can also be uses by people who have had eye surgery for cataracts. Disposable contact lenses have become very popular, though a lot of people use hard contact lenses and gas permeable lenses. Obviously with daily disposable lenses you have more freedom in the sense that you would not mind if you lost any, or if they became scratched. Hard and gas permeable lenses however require looking after. After your eye examination, the fitting and follow up care are important parts of contact lens usage to give maximum benefits of vision, appearance, comfort and tissue integrity.

How to look after your lenses

Try not to leave your lenses lying around after use and make sure you store them in the appropriate container with the cleaning solution. An atmosphere with dust and chemical fumes may damage your lenses if they are left uncovered.

Utmost hygiene must be maintained as contact lenses come into direct contact with your eyes. Always wash your hands before you handle your lenses.

Sterilisation is essential for soft lenses and must be done daily. Sterilisation is the cleaning of the lenses with the prescribed cleaning solution, which is sold along with the lenses.

If an old lens becomes uncomfortable, it may be developing deposits on the lens, scratches or nicks in the lens, or problems with the tears lubricating the surface of the lens. It varies from person to person with how long a lens will remain comfortable. Good care of the lenses will usually extend the life of the lens. Having to replace lenses frequently due to rapid protein deposit formation or other problems is a good reason to consider disposable lenses.

Types of Contact Lenses

Contact lenses are one of the most popular forms of eyesight correction. It has been estimated that there are greater than 3.3 million people in the UK alone wearing contact lenses (The Association of Contact Lens Manufacturers). Contact lenses are used to correct short sightedness (myopia) and long sightedness (hypermetropia), and there are also lenses available for astigmatism and presbyopia. After an eye examination you will be checked to see if your eyes are suitable for contact lenses, and all being well will fit the lenses. The optician will check to see if your tears are good quality to ensure that the lenses are kept lubricated. The optician will also measure the size of your cornea, the pupil and the position of your eyelids to ensure the correct size lenses are fitted.

Contact lenses generally fall into two categories, hard and soft. The contact lenses themselves are held in place by the tears in the eye between the lens and the cornea, the front of the eye. Most contact lenses are worn on a daily basis and should not be worn overnight. Your optician may advise you whether it is safe to wear lenses when sleeping but always check if you are not sure.

Soft Contact Lenses

Soft contact lenses are made from oxygen permeable plastics. They contain between 30 and 40 per cent water and are very pliable, comfortable to wear, as well as being easy to fit.

Astigmatism (the shape of the cornea causes distorts the eyesight) can be treated with “toric” contact lenses. Bifocal contact lenses are used to treat presbyopia, when a person has difficulty seeing close up particularly when reading. This condition was traditionally treated by wearing reading glasses for close up tasks but now bifocals ensure the person can see objects in the distance and as well as for reading.

Hard Lenses

The first contact lenses that were developed were hard lenses. These lenses didn’t allow for oxygen to pass through the lens to the cornea. These lenses needed to be very small to leave as much cornea uncovered as possible so they could easily fall out especially when blinking. These lenses are still available for certain specialist needs, however they have largely been replaced by rigid gas permeable lenses.

Rigid Gas Permeable (RGP)

These lenses combine the functions of both hard and soft lenses. These lenses are firmer than soft lenses, but are made of an oxygen permeable plastic. RGP lenses last longer than soft lenses and are quite hard-wearing. Some prefer to wear these lenses as they are easier to handle than soft lenses. People with a high level of astigmatism are often prescribed RGP lenses. Once a person has got used to the lenses they are generally just as comfortable to wear as soft lenses.

Disposable Lenses

Disposable contact lenses have become very popular these days, especially with those who have a busy lifestyle. There is no need to look after the lenses as they are replaced each day with new lenses and the old lenses are thrown away. It is also means you do not have to worry about losing a lens. The cost of disposable lenses is comparable to other lenses. They are usually not more expensive than non-disposable lenses. Your optician will advise you how often you need to replace the lenses. This can vary from daily replacement to a much longer period.