.: Bifocal Contact Lenses for Presbyopia
Presbyopia is a vision condition in which they eyes are not able to focus clearly on near objects. It usually begins after the age of about forty when the lenses in the eye start reducing in flexibility. Presbyopia affects around 90 million adults in the USA alone and about one in four patients passing through an optometrist’s door will suffer from it.
Symptoms of presbyopia include difficulty in reading, difficulty in seeing in low lighting conditions and, occasionally, headaches.
Traditionally these vision problems were addressed with the old-fashioned reading glasses. Or existing eyeglass wearers could opt for bifocal eyeglasses. However the use of modern contact lenses for use with presbyopia has some distinct advantages beyond their cosmetic appeal. For example they can be well suited to other aspects of a wearer’s lifestyle such as sporting activities, exercising or using a computer.
Recently, contact lenses for correcting presbyopia have become available in more convenient types such as disposable or frequent replacement varieties. Today these are very popular lens types providing obvious benefits for the wearer.
HOW CONTACT LENSES CORRECT PRESBYOPIA
From a technical perspective, there are three distinct ways by which contact lenses can be used to correct presbyopia, each with advantages and disadvantages for particular types of patient. But the important thing here is that there is a choice and each wearer is likely to find one method best suited to their unique situation. The different contact lens methods are as follows:
MONOVISION
The monovision technique involves using in one eye a lens for seeing near objects and in the other eye a lens for seeing distant objects. Many people find that monovision works very well for them. It relies on the brain’s ability to selectively process and combine information from the best available sources in order to provide the clearest possible vision. In some instances, the optometrist might employ a bifocal lens in one eye and a normal distance lens in the other. The main problem associated with monovision is the apparent loss of depth of vision for some patients.
BIFOCAL CONTACT LENSES
As with traditional bifocal eyeglasses, each lens in bifocal contact lenses possesses two powers – one for seeing near objects, the other for distant objects. Some types of bifocal lenses when magnified look a little like a bull’s eye with an central inner zone surrounded by the outer zone. The drawback to this type of lens is that in certain conditions of reduced lighting, the vision might not always be as sharp in certain areas.
MULTIFOCAL CONTACT LENSES
Multifocal contact lenses work very much like the progressive lenses for eyeglasses. These lenses possess several zones of differing power in order to assist the eye gradually as it changes its focus on different objects at different distances. Therefore these lenses are designed to function well for seeing near, intermediate and distant objects. Their drawbacks are typically the same as for bifocal contact lenses, with occasional loss of visual acuity.
Bifocal lenses are available in two basic design types, 'Translating' and 'Simultaneous', the essential characteristics of which are as follows:
TRANSLATING BIFOCAL LENSES
Another name for the translating lens type is an 'alternating lens'. Gas Permeable bifocal lenses are regularly of this type. Their usage is very much like that of traditional bifocal eyeglasses. The wearer will look through one zone for distance vision then ‘translate’ to look through the other zone for near vision. Both zones aren’t looked through at the same time.
SIMULTANEOUS BIFOCAL LENSES
The majority of soft bifocal contact lenses on the market are of the 'simultaneous' type. As the name implies, with simultaneous lenses the wearer actually looks through the various powers of the lenses at the same time. What happens is that the brain steps in and ‘suppresses’ the power or powers, which aren’t needed at that particular time in order to see clearly. There exist further subdivisions of this lens type, but we won’t go into the details in this brief overview.
As with all contact lens selection and wear, choosing the right type of bifocal lens depends equally as much upon the wearer’s unique lifestyle as his unique vision characteristics. For example a patient who regularly undertakes sporting activities will have different needs from one who only needs to wear them socially or for use at work.
However, the success of adopting bifocal contact lenses relies very much on the expectations of the wearer who should realize that, almost by definition, bifocal lenses are very much a compromise and that he or she is never going to regain the acuity of vision in all environments that they had when younger. In most cases this is perfectly acceptable and bifocal lenses have now earned their place in the optometrist’s ever-expanding repertoire.
Article keywords: contact lenses, eye health, eye care, eyes, vision
Article Source: http://www.articles32.com
BY DR. BIANCA TAVARES
Dr. Tavares is a medical consultant with wide-ranging experience and interests in both traditional and complementary medicine and health care.
She has a particular passion for disseminating quality medical information to the people who matter – the patients – and acts in an advisory capacity to numerous journals and health related web sites. Her writing about eye health and bifocal contact lenses can be found regularly at Contact Lens Advisor.
This article is copyright by Dr Bianca Tavares. It can be reprinted freely online as long as the entire article and this resource box are included.
.: New Health Articles
1). Breakthrough: Why Understanding Separation Anxiety Disorder Will Ultimately Cure It
Understanding Separation Anxiety Disorder Will Ultimately Cure It. Separation anxiety is not only common to kids and parents. Believe it or not, it is also what your dog feels every time you leave them.
2). Should You Worry About Global Warming?
What to do instead of worrying about things beyond your control like Global Warming.
3). Causes of Eczema on Hands and Effective Treatment
One of the most annoying forms of eczema is atopic eczema on hands. In this area it can get very irritating indeed. With the constant use of the hands, and their easy reaching access, the itching can become unbearable, and scratching the itch can become a habit which leads to a very severe rash in some people
4). Are You Looking For Simple and Good Panic Attack Help Tips
This article is about how to look for good and simple anxiety attack help tips and what are the various available options for the sufferer.
5). Can Child Panic Attack Be Deadly and What Are Its Tips and Solutions
This article is about what the tips, solutions and options to help the parents and the child, when a child has anxiety attacks.
6). Life as a Compulsive Overeater
This article talks of the struggles of being a compulsive overeater and the cycle of weight loss and weight gain.
7). Improving the Outcome of Stroke
The majority of strokes occur when a blood clot lodges in a blood vessel, blocking blood flow to a portion of your brain (ischemic stroke). The group of brain cells normally nourished by the oxygen in the affected blood vessels dies almost immediately after blood flow is blocked, while surrounding brain cells experience reduced blood flow.
.: Top Health Articles
1). The Hottest Hair Trends And The Sexiest Hairstyles For 2007
Copyright 2006 David Maillie
Hair has become unequivocally important as it can literally make one look like a movie star or a has been from Hee Haw, which died out many years ago. It is big enough that it is a multi billion dollar industry and the average bill in a salon is approaching $100. In the big cities with a hot hairstylist like Jonathon in Beverly Hills prices can easily top $500 for a cut and style.
2). Collarbone Injury
The clavicle or “collar bone” connects the scapula bone in the shoulder to the sternum in your chest. It functions to hold the shoulder upward and backward.
Clavicle fractures are common bone injuries. A break in the clavicle bone is usually a closed fracture that normally takes approximately 6 weeks to heal in an adult, 4 weeks in a child. The injury rarely requires surgery.
3). Cervical Radiculopathy: Diagnosing a Pinched Nerve in the Neck
When a nerve is pinched in the neck’s spinal column, pain can be such a prominent symptom that more subtle, but diagnostic, aspects are overlooked.
By way of background, the spinal cord in the neck is connected to the nerves of the arms through pairs of spinal nerves. These spinal nerves, also known as roots or “radicles,” transmit incoming messages (electrical impulses) from the arms’ nerves concerning sensations of touch, pain, heat and cold on various patches of skin.
4). Can Chocolate Really Kill Your Dog
We have all heard this all of our lives but how big a threat is it really? Is it life threatening or will it just make him sick? How much chocolate does the animal have to eat for it to cause a negative reaction?
5). Get That Flat Stomach Look? Get Rid Of Big Tummy, Pot Belly And Beer Belly Fast.
How to get that flat stomach look and get rid of big tummy, pot belly and beer belly fast?
By exercising your Transversus Abdominus Muscle. This is the muscle in your abdomen that holds your stomach in giving you the flat belly look. This muscle acts like a corset around your tummy by holding your tummy in and if the muscle is weak, your belly will be distended more easily making your tummy looking much bigger than it should just like having a beer belly.
6). How Long Will It Take To Gain Muscles| Build Muscle Mass
There are many factors to consider when you want to know how long will it take for you to gain and build muscle mass. Questions like are you eating enough and the right nutrients to accelerate muscle growth, are you exercising correctly and regularly and do you have the genes for quick muscle growth need to be addressed.
In this article, we shall discuss whether you have the genetic make up to gain and build muscles quickly.
7). Muscle Imbalance And Chronic Injuries
Injuries can occur anywhere and at anytime, but the most prevalent place of occurrence is in the workplace. The reason for such a high rate of injury is that people spend 8-18 hours a day, 5-7 days a week performing unidirectional (one-way) movement patterns, causing an imbalance in the musculoskeletal system that results in the overuse and under use of certain muscle groups.