Prescription eyeglasses are manufactured in a variety of materials. The most basic is the glass lens. The glass lens is by far the best in absorbing ultraviolet light. It comes in several different colors and is, of course, scratch resistant. It is also one of the least expensive. The downfall to the glass lens is the weight of a pair of prescription eyeglasses made of glass. They are also very breakable and have to undergo a heat-treated process to ensure durability.

Another material used to manufacture prescription eyeglasses is the High-Index plastic lens. It also absorbs ultra violet light well. This type of lens is much lighter in weight than the glass lens; however, they are also very expensive and can be scratched very easily.

Resin Plastic is another type of material used in manufacturing the prescription eyeglass lens. They are the lightest of all lenses, but do not offer the high level of protection against ultra violet light that the other lenses offer.

Some prescription eyeglasses are tinted with a wide variety of colors and shades. The purpose of the tint is to reduce the glare from certain situations: such as bright lights, computers television sets, etc. Another reason for the tinting of the lenses are to offer comfort to the eyes. Also, people order tints on their eyeglasses for the fashion.

Glass and most plastic lenses are coated with a UV protection coating. Ultra violet rays can cause severe damage to the eyes. It is very important to protect your eyes while out in the sun.

Another coating that is added to a pair of prescription eyeglasses is the scratch-resistant coating. Sometimes this coating is applied at the manufacturer and other times it can be added right there at the eye doctors office. It must be said, however, that even while this coating can aid in the durability of the lens, it does not make the lens scratch proof.

A person should have their eyes examined by an optometrist every two years or every year after the age of 60, to determine whether they need to wear prescription eyeglasses. Also, If any of the following symptoms occur, then an eye exam needs to be scheduled.

* If a person is having a hard time focusing in on objects.

* If the eyes are red or swollen for unknown reasons.

* If unusual headaches reoccur while reading, watching television or working on a computer.

There are several different tests performed by an optometrist during a routine eye exam to determine whether prescription eyeglasses are needed.

A glaucoma test is a simple, painless test. Glaucoma is a build up of fluid in the eye that causes the retina to have pressure. Glaucoma doesn’t really have any symptoms, but over time can cause total vision loss.

A peripheral vision test determines the degree of side vision that a person has.

Then there is the Visual Acuity test, which is the test that determines one ability to distinguish letter, shapes and number in various sizes and from various distances.

There are three professions that work with the eyes.

An Optometrist examines the eyes for diseases and medical conditions. They are licensed to dispense prescription eyeglasses, contact lenses, and any needed medications.

An ophthalmologist is an eye doctor that can perform any needed eye surgeries. They work very closely with the optometrist.

An Optician is a person that makes the lenses, frames and contact lenses. They analyze the prescription that the Optometrist has given. They assist with fitting frames and lenses.

If the exam concludes that prescription eyeglasses are needed, the optometrist will then either help you decide which frames and lenses best suits your specific needs, or refer you to an optician.

Prescription eyeglasses are glasses that have been prescribed by an optometrist to be worn by someone who has been diagnosed with a certain eye condition. Depending on the condition, a different lens will be prescribed.

Prescription eyeglasses are broken down into four different categories.

The Single Vision Lens has the same focal power from the top of the lens to the bottom of the lens. People who have been diagnosed as farsighted, nearsighted or with having astigmatism can wear single vision lenses to correct these types of eye disorders. Astigmatism is a condition that doesn’t allow light to reflect on the retina, thus causing distorted images.

A Bifocal Lens is used to correct a condition call Presbyopia. This disorder usually occurs in people in their late 40’s. If a person has been diagnosed with Presbyopia, they can’t focus in on close objects. That is where the Bifocal Lens is helpful. The top of the lens is used for distant vision and the bottom of the lens is helpful with close vision. People with Presbyopia need both types of Focal View on their prescription eyeglasses.

The Trifocal Lens-meaning they have three focal views-is designed similar to the bifocal lens with the exception to the center focal point on the lens is for intermediate vision.

The fourth type of lens is the Multi Focal lens. It has more than one focal view; therefore a Bifocal and a Trifocal are types of multi focal lenses.

Other types of lenses that are specially designed for other purposes include the Computer Lens. They are designed so that when sitting at a computer, a person can view the monitor and papers nest to the monitor at the same time. And then there are Double Bifocals, which are rarely prescribed, but when they are it is usually for pilots, electricians or other professions that need to have close vision overhead.

From documents that were retrieved in Rome in the 13th Century, we know that prescription eyeglasses were available at that time. They were referred to as “spectacles” rather than glasses. Although we do not know for certain when prescription eyeglasses were invented, we do have proof that they did exist during this time period. A portrait done by an artist named Tomas da Modeno portrays a gentleman wearing eyeglasses. Obviously what we do not know is if they are prescription eyeglasses. There are, however, other documents such as a manuscript written by a man that implies that if the he wasn’t wearing spectacles, he would not be able to read or write.

In the 15th century the printing press was invented which meant more reading material was readily available. Thus, the need for prescription glasses increased. The first reading glasses were held by one hand only during the times that they were needed for reading. It was later in the 17th century when people actually wore the glasses regularly, after an optometrist created them with both earpieces. In those times, a person who was having difficulty with their eyesight would just go in and try on several pairs of prescription eyeglasses until they found a fit for their needs. That changed when Dr. FC Donders wrote the first book on examining the eyes to get prescription eyeglasses.

Benjamin Franklin is credited for the invention of the bifocal lens. With a bifocal lens the bottom half is used for reading and the top half is for seeing objects that re further in the distance.

The first lenses in the prescription eyeglasses were made from quartz crystal and very low in quality and durability. Then in the early 1900’s, Bausch and Lomb created the glass lens. Today most prescription eyeglasses are made from a plastic material that can be polished and tinted like glass lenses. The advantage to the plastic lens is the lighter weight of the prescription eyeglasses as well as the durability is greatly increased.

Which is better, eyeglasses or contact lenses?

This bout is scheduled for 5 rounds…

There is no cut and dry answer to this question. While eyeglasses vs contact lenses is not a bout that would sell out Ceasar’s Palace, it is of importance to most of us who rely on vision correction.

Because the eyeglasses vs contact lenses debate is of such interest to so many, Let’s look at the general pros and cons for each type of vision correction.

I’ll give you the facts and you can then decide for yourself which is best for you.

Round 1 - Quality of Vision:

Eyeglasses provide crisp clear and consistent vision straight ahead. There are not many variables to vision throughout the day because with glasses you are looking through a solid piece of plastic.

Contacts give you good straight ahead vision, however it is not as consistent as with glasses. Soft lenses are made of plastics and water and are therefore prone to change with environmental variables. For example, air conditioners and circulated air can cause your lenses to dehydrate leading to blurred vision. To clear your lenses, all you need to do is blink.

Round 2 - Distortions:

Eyeglasses again, give you great crisp vision straight ahead. Anything that is not straight ahead will have an element of distortion. The stronger your correction and the more astigmatism you have, the greater the distortion will be. If you are nearsighted (minus lenses) everything will seem small and far away with glasses. If you are farsighted (plus lenses) everything will appear larger and closer.

Because contact lenses rest directly on the eye, distortion is drastically reduced. In fact, people who have high corrections and are new to lenses often take a little time to get used to seeing without distortion. Contacts give you more true to life vision.

Round 3 - Peripheral Vision:

Eyeglasses do not give you any peripheral vision. Any area of the lens you look through except the optical center will give you a distorted image. If you are wearing glasses, your entire head needs to move to see an image clearly, which makes backing up a car very difficult for many.

Contact lenses provide a full range of vision; furthermore, you can move your eyes only and still see clearly. Peripheral vision is a huge plus of contact lenses.

Round 4 - Comfort:

When properly fit, eyeglasses can be very comfortable. With new lightweight lens materials and frames, most any prescription can look and feel good. The higher the prescription and the larger the frames, the thicker (and heavier) the lenses will be.

Contact lenses, when fit correctly, are also extremely comfortable. Regardless of the correction, there is no heavy frame on your face or thick lenses to weigh you down. Certain eyes may take a little more time and patience to find a comfortable fit. In my experience; most anyone can wear comfortable contact lenses.

Round 5 - Style:

Frames can be stylish. No doubt about it. It’s the lenses in the frame that can make them, err… not so chick. High minus lenses have thick edges and give the appearance of small beady eyes. High plus lenses have thick centers and give the appearance of large, magnified, eyes.

With contact lenses, nobody has to know you are wearing them. Unless you want them to know you wear lenses. In this case you can wear colors or theatrical lenses to accessories your eyes.

The results are in: Now you have the facts, you can decide for yourself which is best for you. With the comfort and ease of contact lenses today, there is nothing wrong with wearing contacts part time and glasses the rest of the time.