Posts Tagged ‘test’

Cataracts and vision loss

One quarter of all people in the UK aged over 75 will develop cataracts and after the age of 50 your chances of having cataracts really begin to increase. A cataract causes damage to the eye lens and the only available treatment to restore vision damaged by cataracts is the removal of the cataract and the damaged eye lens. Cataract surgeons then replace the natural eye lens with an intraocular lens to restore vision.

What is a cataract and what causes cataracts?

A cataract damages the eye lens, distorting the way light enters the eye and causing vision to become cloudy.

The eye lens works like a camera: light enters the eye and is sent in a clean line backwards through the eye to the retina. From the retina, electrical images are sent to the brain and these images are what we see.

When the eye lens becomes clouded by a cataract, light defracts as it enters the eye, sending fractured images towards the retina. The images we see become distorted or ‘cloudy’.

Cataracts are caused by a build up of proteins in the eye. These proteins gradually clump together and damage the eye lens. The longer a cataract is left untreated the more proteins that cloud the lens and the more damaged vision becomes.

Cataracts area common problem for people over the age of 50 – with 1 in 4 UK patients developing a cataract in a lifetime. Cataracts develop gradually with age but can also be caused by damage to the eye or as the result of a genetic problem in the case of congenital cataracts.

Different types of cataract can damage different parts of the eye lens and more than one cataract can develop at once. Cataracts commonly occur in both eyes at the same time.

What are the symptoms of a cataract?

The most common symptoms of cataracts are blurred or cloudy vision, difficulty in seeing bright colours, seeing halos or glare around bright lights and poor night vision. Cataracts symptoms will vary according to the type of cataract. As the cataract develops, symptoms of blurred, cloudy vision will increase and vision deteriorates.

How do cataracts develop and progress?

Once a cataract starts to develop, the condition will get worse over time. The speed a cataract develops will vary between patients but the more advanced a cataract becomes the more damage is caused to eye sight.

How are cataracts diagnosed?

Cataracts must be diagnosed by a qualified opthalmologist. The symptoms of cataract may be similar to those of another eye condition and it is important patients have a consultation with an eye clinic before booking cataract operations online.

To diagnose a cataract the opthalmologist will perform a series of eye tests:  a visual acuity test, pupil dilation test and a tonometry test. These tests can diagnose a cataract in the very early stages of cataract development which is why regular eye tests are strongly recommended, especially for people aged over 65.

What is recovery like after cataract surgery and what results can I expect?

Cataract surgery is performed as an outpatient operation. The surgery is complete within one hour and patients are able to return home the same day.

Immediately after cataract surgery, vision will be blurred due to the eye drops used to dilate and numb the eye for surgery. Patients are generally prescribed eye drops to protect the eye from infection as it heals and the new replacement lens settles in the eye. It is important that patients try to avoid irritating the eye until fully healed and waering an eye patch while sleeping can prevent rubbing the eye and causing a problem.

The recovery from cataract surgery is fast – most patients feel only a slight ache in the eye for one-two days post-surgery.

The results of cataract surgery are excellent with 95% of patients reporting an immediate improvement in their sight*. Patients can expect an end to blurred vision, annoying glare and halos from bright lights and an improvement in night vision.

What are the risks and complications of cataract surgery?

As one of the most commonly performed ophthalmology procedures, cataract surgery enjoys a very low complication rate and the surgical risks are low. However, as with all surgery it’s important to understand the risks and complications surrounding cataract surgery to help you make appropriate arrangements for the recovery period.

Frequently asked questions about cataracts

Will you be able to see or feel anything during cataract surgery? How long will the new lens last? You can find the answers to the most often asked questions about cataracts and cataract surgery by visiting our cataract FAQ page.

*statistics from NHS Choices

Article Source:http://www.articlesbase.com/vision-articles/cataracts-and-vision-loss-1583882.html

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Animal Testing A Tragic Disgrace

Toxicologist John Draize, 65 years ago, invented the “rabbit test” as a standard for measuring eye damage when exposed to chemical agents. The rabbits are held in a brace preventing them from moving their bodies or heads for 21 days or longer after the chemical has been introduced into their eyes. The eyes are then evaluated for redness, corneal damage, structural changes and alterations in the anterior section of the eyes. The animals are then useless to the researchers since the eyes have been compromised.

This practice subjects the rabbits to pain and suffering and treats them like disposable tissues. It is a terrible, heartless method that demonstrates a total lack of respect for other living creatures that feel pain and fear as much as we do. Fortunately, there is an alternative method utilizing cow and chicken corneas from dead animals. This procedure has been approved by both the US and Europe. The dead tissues are exposed to the same irritants and studies instead of the live subjects. There is NO pain and NO suffering!

According to Thomas Hartung who is director of the Center for Alternatives to Animal Testing at John’s Hopkins University, the Draize eye test should become history as this and other alternative become available. The germ killing cleaning products no longer have to be tested on live rabbit eyes to see if they are safe.

We as humans have an obligation to safeguard the safety of animals. They are at our mercy and using them for this kind of testing shows a lack of respect for other life. We must employ methods that do not put animals at risk and expose them to pain. Only lab tests should be permitted and when safety and efficacy have been determined then human volunteers can be used. Animal testing never gives us the actual response anyway, so why torture these poor living creatures.

Dr. Jay B Stockman is a contributing editor for VisionUpdate.net, and a practicing doctor for New York Vision Associates, http://newyorkvisionassociates.com,

Article Source:http://www.articlesbase.com/vision-articles/animal-testing-a-tragic-disgrace-1433192.html

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Low contrast sensitivity tests and treatments

Good vision such as 20/20 does not mean satisfying contrast sensitivity. Common vision tests using black letters or numbers displayed against white backgrounds can not reflect your exact contrast sensitivity, since the real world is filled with grey shades. So that special contrast sensitivity testing is necessary.

May eye diseases or conditions may cause poor contrast sensitivity, such as cataracts, glaucoma, and diabetic retinopathy, as well as the side effects from LASIK and PRK. People with low contrast sensitivity may have difficulty in some conditions, such as seeing traffic lights, spot other cars and pedestrians during night driving. Since these people have poor perception of objects that do not stand out from their backgrounds, they may even stumble when they fail to see similarly colored pavements.

The term “contrast sensitivity function” (CSF) is used to describe people’s low contrast seeing ability. A contrast sensitivity test may be included in a routine screening after the visual acuity test, which measures the ability of seeing detailed letters or numbers. With your plastic eyeglasses or contacts lenses wearing on, your eyes will be tested in together by a low-contrast test chart, which consists of bars and dots in different colored contrasts that are used to evaluate the patient’s exact CSF. Your CSF will certainly be affected by the sizes of objects: the larger the objects are, the higher CSF you can achieve.

By testing your eyes using bar and dot patterns displayed against varying contacts or intensities, your highest and lowest contrast sensitivity can be determined and plotted into a curve, which shows your contrast sensitivity readings. Tests under both bright and dark conditions can provide more detailed information about your images process capability.

As a volunteer, you can get a contrast sensitivity test as a necessary part of the evaluation of new ophthalmic devices such as LASIK excimer lasers and new intraocular lenses required by FDA. Once you are diagnosed with low contrast sensitivity, some remedies are available, depending on the source of the problem. Usually, artificial lenses with a yellow filter can improve contrast. If the low contrast sensitivity is caused by higher-order aberrations, wavefront lenses or LASIK are the right choices. Another option is intraocular lenses with yellow tints, which can also offset low contrast sensitivity.

Article Source:http://vision.firmoo.com/eye-exams/low-contrast-sensitivity-tests-and-treatments.html

Vision Library is the information source in area of vision care, including eyeglasses, sunglasses, contact lenses, sports protective eyewear, vision error and diseases, vision surgery, ageing and kid’s vision etc., solely sponsored by Firmoo.com, an emerging online optical store offering high quality eyewear at the lowest prices.Firmoo’s return and refund policy make any purchase risk-free.

Article Source:http://www.articlesbase.com/vision-articles/low-contrast-sensitivity-tests-and-treatments-1408662.html

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See The Benefits Of Eye Tests

If you don’t currently wear glasses or contact lenses, you might find that when you think of an eye test the picture conjured up in your mind is the card and chart of your school days. While eye tests when you were a child were great for identifying those who might need help in correcting problems with their vision, eye tests have come a long way since.

These days eyes tests combine traditional testing methods with new techniques and technologies to get an in-depth picture of the health of your eye. For those that do wear contacts or glasses, regular eye tests are essential for making sure that their prescription is up to date and best for their eyes. For those that don’t at the moment, tests can identify if there are any signs of weakness in the eyes.

While many people wouldn’t consider having an eye test unless they are having problems with their vision or are experiencing commonly known side effects such as headaches, eye tests are for much more than checking whether you are long or short sighted. Advances in technology mean that these tests can now help spot the warning signs for other aspects of eye health.

For example, an eye test will allow opticians to pick up on the early signs of eye diseases such as glaucoma and cataracts and can also be vital in the early detection of health problems such as diabetes or high blood pressure. This means that eye examinations are far more in-depth than ever before.

When you go for an eye test, you’ll find that your optometrist will be interested in much more than how clearly you can read the infamous letter chart. They will also compile a detailed history and details of your lifestyle, they will also use autorefraction to determine your baseline prescription and they will use tonometry to measure the pressure in your eyes – this is vital as it’s a key factor in identifying glaucoma.

Your optometrist will also conduct a slit lamp exam, allowing them to look at your cornea, conjunctiva, lids, iris and lens under high magnification with the help of a microscope and a small beam of light. They will also be examining the strength and flexibility of your eye muscles and carrying out a full retinal exam, to ensure that they have a broad and comprehensive picture of the health of your eyes.

A modern eye test may sound complicated, but your optometrist will talk you through the process and ensure that you get the best out of your exam.

Adam Singleton writes for a digital marketing agency. This article has been commissioned by a client of said agency. This article is not designed to promote, but should be considered professional content.

Article Source:http://www.articlesbase.com/vision-articles/see-the-benefits-of-eye-tests-1320629.html

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Contact Lenses Without Prescription

Let’s start by explaining what we mean by “prescription” as there are two meanings in this context and there is often confusion.

Just as glasses can be prescription or non-prescription, so too can contact lenses. Prescription lenses or glasses are intended to correct a vision disorder whereas non-prescription contact lenses or glasses are effectively clear.  That is, they do not alter your vision. Colored contact lenses are a typical example of  non-prescription contact lenses although it is now possible to get non prescriptioon contacts in a range of colors.

The other thing we mean by the word “prescription” is the piece of paper you get after a sight test which explains the type of contact lens you need to correct your vision.  It will detail the curvature of the lens and the strength of the lens.

People who want to buy contact lenses without prescription usually mean that they haven’t had a recent eye test but they want to buy lenses based on their last known prescription.  This is also true of people wanting to buy non prescription colored lenses without a prescription.

If you think that your eyesight hasn’t changed you probably think it quite reasonable to buy lenses without an up to date prescription.  The same applies if you want to buy colored lenses.  The fact is, however, in many countries it is simply impossible to buy contactlenses without prescription, whether they are prescription lenses or not and whether they are colored or not.

You may think that this is unfair, after all, it’s your eyes which might be at risk.  But remember this.  You only have one pair of eyes and you want to be certain not only of the quality of the lenses you are putting into your eyes but that they are suitable for your eyes.  Not every make of lens suits every person, and not every lens will fit your eye. A regular eyesight test will also pick up on any other problems which might have developed in your eyes since your last test.

It makes a lot of sense to get a current prescription, even if you do happen to live somewhere where you can buy contact lenses without prescription.

For more information on getting contact lenses with no prescription, please see www.contactlenseswithoutaprescription.com.

Article Source:http://www.articlesbase.com/vision-articles/contact-lenses-without-prescription-1321464.html

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