Jumat, November 17, 2006

Myths about eye

Mitos-mitos seputar kesehatan Mata. diambil dari www.agingeye.net.

Myths about Vision and Eyeglasses
● "Although eyeglasses makes you see better, they cause vision to get worse over time.
Eyeglasses will need to be constantly changed with higher powered one."
● "Don't wear your glasses so often, you need to exercise your eyes!"
● "Overuse of the Eye' or 'use of eye' makes vision worse"
● "Sitting Too Close to the TV Is Bad for Your Eyes"
● "Reading in the Dark Will Damage Your Eyes"
● "Eye exercises can improve vision"
● "Over the counter reading glasses hurt the eye"
● "Wearing contact lenses will prevent nearsightedness from getting worse"
● "Eating carrots can improve vision"
● "Using night light in infant rooms will make then nearsighted"

The Facts
Before you start wearing glasses, you are accustomed to seeing a blurry world around you. Since this is all you have seen ever - you accept it as normal. When your vision is corrected with eyeglasses you start seeing a clear world. Now when you remove your eyeglasses after wearing them for several months - you are presented with the same blurry world as before. You feel you were able to get around without wearing glasses before but now when you remove glasses you see all blurry and cannot get around. In reality its your perception that has changed. Now you know the difference between clear vision and blurry vision and do not accept the blurry world.
Of course it is possible that your eye power may also have increased as you age - but this increase would have happened regardless of whether you wore the glasses or not. Using you eyes for any length of time does not make them weaker. You may get tired and may even get a headache with long reading hours, but these symptoms have nothing to do with eyes getting weaker. Sitting closer than necessary to the television may give you a headache, but it will not damage your vision. Modern TVs do not emit harmful radiation, so eye damage due to radiation is also not an issue. As with sitting too close to the television, you may get a headache from reading in the dark, but it will not weaken your sight.
Any eyeglass or contact lens of the right prescription will help you see comfortably. Contact lenses have a cosmetic advantage - but they do not offer any beneficial affects like preventing nearsightedness from getting worse. Usually people over the age 40 need reading glasses. Over-the-counter reading glasses may be fine if they allow you to read comfortably. These reading glasses do not hurt your eyes. Taller people can stretch their hands further, so if you are 6 feet plus in height, you may be able to get by without reading glasses till late 40s by holding the reading materials further from the eye.
There are no eye exercises that will help your eyes see better or that will prevent the nearsightedness from getting worse. The article 'Can Eye Exercises improve vision?' provides information on how the concept of eye exercises helping vision came about. Some of the eye exercise methods are the 'Yoga method' and the 'See Clearly method'. Carrots won't improve eyesight for someone eating normal healthy food. However, carrots are rich in beta carotene, which is converted into Vitamin A in the body. Vitamin A is important in maintaining normal vision, and worldwide, Vitamin A deficiency is a leading cause of blindness. Therefore in the developing world, where deficiency of vitamin A is possible, eating carrots may be good advice.
● In the May 13, 1999, issue of the highly respected medical journal Nature, a group from the University of Pennsylvania have raised the alarm that the use of a night light in the rooms of infants may be a factor in the development of myopia (near sightedness). This is a very controversial issue.


Cataract Myths
● "Vision improves in older people as they gain second sight"
● "A cataract is a new growth inside the eye"
● "Cataract has to become 'ripe' before it can be removed"
● "Cataract is removed using lasers"

The Facts
The "second sight" refers to ability of a person to see better, usually upclose, as they age. The reason for this "improved" vision is that the lens power changes due to increasing cataract. So actually second sight is due to the cataract having advanced.
A cataract is not a new growth in the eye, rather it is a term that means that the lens or its capsule (normally transparent) have now become less transparent due to the lens substance (fibres) becoming opaque. Any opacity of the lens is referred to as 'cataract'. Cataract is not a new growth in the eye or lens.
The concept of waiting for cataract to become 'ripe' before it can be removed is valid when the surgical procedure used is the one where a large incision is made and the lens is manually removed. Given the higher likelihood of potential complications with this earlier surgical procedure, it made sense to wait till the vision became really bad - and that meant waiting for the cataract to get advanced or 'ripe'. The modern surgical procedures use a very small incision (that usually closes without suturing) and an ultrasound (phacoemulsification) machine. Although the procedure is not without risks, it is very safe in experienced hands. Therefore if any patient complains of reduced vision that is interfering with their routine daily activities, then cataract surgery may be offered. At this point the cataract may not be far advanced or 'ripe'. The risks and benefits of the surgery have to be debated by each patient individually, since what is limitation of routine activity for one individual may not be considered as important by another individual.
Cataract is not removed with lasers. An ultrasound (phacoemulsification) machine is used to remove the cataract. Sometimes, several months after cataract surgery, the transparent membrane behind the intraocular lens may become hazy and reduce vision. A YAG laser is then used to make an opening in the capsule.


Glaucoma Myths
● "Glaucoma is a disease of old age"
● "I have 20/20 vision so I don't have glaucoma"
● "My eyes would hurt or feel different if I had glaucoma"
● "Canola oil causes glaucoma"

The Facts
Although it is true that the risk of developing glaucoma becomes higher with increasing age, younger people also may develop glaucoma especially if you are an African-American. Glaucoma affects the peripheral vision first. The central vision is affected when the glaucoma is far advanced. Therefore you may be able to read 20/20 (central vision) and still may have glaucoma. A peripheral field of vision test (using an automated field testing machine) is required to detect early glaucoma.
In general there are no symptoms (eyes do not hurt), which is why glaucoma is often referred to as the 'sneak thief of vision'. There is no evidence of Canola oil causing glaucoma.

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