[FW] Glasses or Contacts?

Glasses or Contacts?

So you’ve had your eye exam and are now ready to fill your new prescription. An eye doctor or optician reviews your prescription and asks whether you are interested in glasses or contact lenses. You would normally choose from the hundreds of glasses frames on display. But with all the latest advancements in contact lens technology, you’re suddenly torn – glasses or contacts?
Both glasses and contact lenses are used to correct refractive errors such as nearsightedness, farsightedness, astigmatism and presbyopia.
Many Canadians choose to wear contact lenses instead of glasses due to the benefits they offer, such as:

• they don't slide down your nose or fog up in winter;
• they don't bounce up and down while you play sports;
• they're less obvious than glasses;
• they may provide better vision and are more comfortable than eye glasses; and
• they do not interfere with peripheral vision.

While your eye doctor can best recommend whether or not contact lenses are suitable for you, here's a look at what's available and what you should keep in mind.

Contact Lenses 101

Contact lenses are medical devices and should be fit to your eyes by an eye doctor. They are designed to rest on the cornea, the clear outer surface of the eye, and are held in place mainly by sticking on to the tear film that covers the front of the eye.
As the eyelid blinks, it glides over the surface of the contact lens and causes it to move slightly. This movement allows the tears to provide enough lubrication to the cornea, as well as flush away any debris between the cornea and the contact lens.
Contact lenses are made of many different types of plastic, but in general, they fall into two main groups: soft contact lenses and rigid gas-permeable (hard) contact lenses.

Types of contact lenses include:

Daily-wear contact lenses – These lenses are designed to be worn only during waking hours, usually up to a maximum of 18 hours. Daily-wear lenses are removed at night and should be cleaned and disinfected after each removal. Daily wear lenses can last up to one year.
Disposable contact lenses – These lenses are designed for short-term use during waking hours. Depending on what type of lenses you have, disposable lenses may need to be replaced daily – you throw them away after one use – or longer intervals, up to three months. Most disposable contact lenses are designed to last up to two weeks. It is important to throw these lenses away as often as recommended by the instructions that come with them, or as recommended by your eye care professional.
Extended-wear contact lenses – These lenses are specifically designed to provide enough oxygen to the eye even while you sleep. You can wear these lenses continuously, ranging from seven to 30 days. These lenses should only be worn as long as recommended by the manufacturer and should be cleaned and disinfected as recommended the manufacturer or by your eye care professional.
Rigid gas-permeable (hard) lenses are made of harder plastic materials that do not contain water. Although hard lenses are not as flexible as soft contact lenses, they allow more oxygen to pass through the cornea reducing the risk of corneal irritations. Rigid gas-permeable lenses need to be replaced less frequently than soft contacts, on average, once every two to three years.
There are some things you should keep in mind before deciding on contact lenses. Contact lenses – with the exception of daily disposable lenses – require regular cleaning and disinfection. Although this process only takes a few minutes, a lot of people do not bother doing it. The most common eye problems encountered by contact lens users are excess tearing, itching, burning, sensitivity to light, dryness and occasional blurred or distorted vision. These conditions may be worsened by improper care or cleaning of contact lenses and increase the risk of developing an eye infection.
Clinical studies suggest that the extended use of contact lenses, particularly overnight, seriously increases the risk of developing corneal ulcers, also known as ulcerative keratitis. An ulcer can scar the cornea in a day or two, leading to permanent scarring or even blindness. Many eye doctors advise their patients not to use extended-wear contact lenses for this reason.
Some problems caused by contact lens wear use do not produce symptoms, but may still harm the eye. For this reason regular examinations by an eye doctor are recommended.
Not everyone is able to wear contact lenses for numerous reasons, which include:

• frequent eye infections;
• allergy eyes; and
• dry eye due to insufficient tear production.

You should also take into account your daily surroundings when considering contact lenses. For example, if you work in an environment that is dusty or where you are exposed to chemical fumes, you may be advised not to wear contact lenses. Also, if you work or live in an environment that is exceptionally dry due to heating or air conditioning, you may find wearing contact lenses uncomfortable.

So What about Glasses?

Glasses may seem like an ancient way to correct refractive errors when compared to contact lenses or laser eye surgery, but in many ways they are more popular than ever.All you have to do is step into an optical store and see the hundreds of fashionable frames on display.
Advances in glasses lens technology and design help eyes see better and appear more attractive even when stronger prescriptions are needed. Thick, coke bottle glasses are virtually extinct.
Here are some of the most popular types of lenses prescribed today:
Aspheric lenses – Provide clearer vision and a wider field of vision than conventional eyeglass lenses, which have a front surface that is spherical, shaped much like the surface of a ball. Aspheric lenses have a more complex front surface that gradually changes curve from the center of the lens all the way out to the edge. There is minimal distortion of the user’s eyes, producing better appearance.
Polycarbonate lenses – A type of shatter-resistant plastic, considered a major advance over earlier plastics used in lens fabrication. These lenses are lighter, thinner, tougher and scratch-resistant. They are ideal for children and active adults.
Photochromic lenses – These lenses have chemical coatings that allow them to quickly darken in bright conditions and quickly return to normal in ordinary indoor lighting or at night.
Anti-reflective coatings – These lenses can dramatically improve the look and comfort of your glasses by minimizing reflected light that might otherwise appear on the lens. An added benefit to this is reduced glare, which eases eye fatigue.
Multifocal eyeglass lenses available for presbyopia, eye's diminished ability to focus that occurs with aging, include:
Bifocal lenses – with two ranges of vision – near and far. A noticeable line separates the two ranges.
Trifocal lenses – with three ranges of vision – near, intermediate and far.
Progressive lenses – These lenses have many advantages over bifocals and trifocals because they allow the user to focus at many different distances, not just two or three. Progressive lenses have no lines and allow a smooth comfortable transition from one distance to the other. Ideal for active, multi-tasking people.
It is important to keep in mind that some lenses may not be suitable for all frames. Progressive lenses, for example, often don’t work well with smaller frames. It is a good idea to consider your lens selection first before you choose a frame.
Your appearance, personal taste and lifestyle are your best guide to choosing glasses and/or contacts. Your eye care professional can best recommend what is suitable for your eyes.




http://www.cnib.ca/en/your-eyes/eye-care/glasses-0707/Pages/default.aspx