Aging eyes and bifocals

Aging causes several problems for individuals, weakening bones, hearing loss, and vision problems. Typically vision problems begin around the age of 40. Individuals that have problems focusing on near and far distances are often given bifocals to help them see better. Benjamin Franklin is given credit for inventing bifocals. Benjamin Franklin had problems focusing on objects close up and far away. His condition is known as presbyopia which means near-sighted and far-sighted. Benjamin Franklin had 2 sets of glasses, one for seeing things up close and another for seeing things far away. Franklin was bothered by the consistent changing of glasses and he created the first bifocal lenses. Franklin cut the lenses of each type of lens in half and fitted them into one singular eyeglass frame and thereby was given credit for creating the first pair of bifocals.

How do bifocals work?
Bifocal lenses can come in glasses or in contacts. Bifocal lenses will have two different types of lenses in each eye. The lens will have an upper lens and a lower lens. The bottom lens is used to correct near-sighted vision and the upper lens is used to correct far-sighted vision. Some individuals have a near-sighted bifocal lens only and the upper lens does not have any type of correction in it.

There are 4 different correction types for near-sighted glasses. The first type is to have a round segment in the lower part of the lens. Other individuals will not be able to look at the glasses and notice that there are two different types of lenses. The second type is to have a semi-circle lens. This lens looks like a half moon because it has a flat top and a round bottom portion. Generally the semi-circle lens can be seen by other people. The third type of near-sighted lenses is the rectangle shape. The rectangle is very narrow and looks like a small ribbon in the glasses. The final type is the bottom portion style bifocal lens. This style has a dividing line between the two lenses and is noticeable by others.

Determining if you need bifocals
Most individuals that need bifocals find themselves straining to read or to look at things close up or far away. Headaches caused from squinting or straining is often a common warning sign that you may need bifocals.

Here are a few other factors that cause an individual to need bifocals:

• Difficulty focusing when reading or moving things further away to help you focus and read.
• Difficulty seeing close-up things or performing close-up tasks like typing or needlepoint.
• You get sleepy when you read at any time of the day because you are straining.
• Difficulty reading in dim light.
• Problems seeing when driving at night.
• You currently wear eyeglasses and have any of the above problems with your current eye glasses.

If you have any of the above symptoms, you should contact your ophthalmologist to have an eye exam or a prescription lens change.

The Eye Exam
When an individual notices they have an eye problem, they will be given an eye test to determine their vision. The standard eye chart is called a Snellen eye chart.
Normal vision is called 20/20 vision. What 20/20 vision means is that when an individual stands 20 feet away from a chart, they are able to see everything on the chart and decipher what the letters or symbols are. The higher the second number, the worse your vision will be. In order to pass a driver's license test, an individual must have 20/40 vision. A person will be declared legally blind if they have 20/200 vision. Snellen eye chart exams can be printed out and given at home. In order to use the Snellen eye chart, they must have another person watch the chart as they read the letters. The chart must be 20 feet away from the individual and there will be 7 different lines on the chart. The lowest line will mean your vision is 20/10. After using both eyes to read the letters, you should cover one eye and test to see if one eye is stronger than the other.

While a home eye test will test your vision ratio, the eye doctor will perform different tests to check the eyes for viruses and eye diseases. Everyone should have a complete eye exam every one to three years, depending upon their history. Children should have a complete eye exam at 6 months of age, at age 3, and again when they start school. Children that do not have eye problems should continue to have their eyes tested every 2 years. Once an individual reaches the age of 40, they need to have their eyes tested every year. In a normal performing eye, the natural lens is attached to muscles that contract and relax. The lens will change shape to help the eye properly focus. Individuals that have presbyopia (near-sighted and far-sighted vision), have weakened muscles and those muscles have lost their flexibility to focus. The weakened muscles mean the eyes have a harder time concentrating, causing the individual to squint. An individual can go throughout their life only to find out they need bifocals at the age of 60 because the eye muscles have weakened over time.

The eye doctor will perform a contrast sensitivity test, a Wavefront eye exam, and visual field testing to determine if you need bifocals. The contract sensitivity test will check the eyes for problems beyond what a person can see on the eye charts. Contrast sensitivity testing is used to determine problems individuals may face in daily life, not just reading problems. The contrast sensitivity test will measure your eye's ability to detect detail. It is often called functional vision. Individuals with low contrast sensitivity generally have problems seeing in darkness. These individuals need extra light to read and may have problems with night driving.

The next test the doctor will perform is a visual field test. The visual field test will give the doctor a full view of what you are able to see peripherally. Individuals that undergo visual field tests may have blind spots, which could be a result of eye disease. Glaucoma is detected in visual field tests. Another benefit of visual field tests is their ability to help doctors identify tumors or problems from strokes.

Problems with bifocal lenses
Bifocals have been known to cause headaches and dizziness in some users. The different lenses take some getting used to and they can be hard for some people to adjust to. Since the lenses are different for the bottom of the glasses from the top of the glasses, the individual needs to train their eyes to look down or up depending upon what activity they are doing. Most readers need to adjust their reading material or their head in order to properly focus on the words.

A common problem several bifocal lens wearers have is computer monitor problems. It is easy for the eyes to have muscle fatigue when they are staring at a computer screen that is placed directly in front of them. The head consistently moves when it is at the computer and the eyes tend to work harder. Several bifocal lens wears keep a pair of single vision lenses that are only worn when they are at their computer monitor.

Another disadvantage with bifocal lenses is the "line" that the wearer may have to get used to. Depending upon the style of bifocal lens, the glasses may have a line directly in the middle or just below the middle of the glasses that separates the two lenses. Individuals that have a visible line often are only bothered by it while others with a merged line can sometimes have blurred vision.

Tests have shown that it will take 24 hours or longer for the eyes to adjust to the bifocals. During the first 24 hours, patients will experience some dizziness and headaches, as the muscles are getting used to the new lenses. Individuals with bifocals should start training their eyes to look through the proper lenses, as it will help to reduce the dizziness and headaches. One way to train your eyes with bifocal lenses is to look at something close up for a great deal of time, such as a newspaper, magazine, or book. After about 15 minutes or longer, focus on something far away for 5 minutes. This will train the eyes on how to use the lenses. Even individuals that have been wearing bifocals for a long time should do these exercises because it will help keep the muscles strengthened.

Each year, about 4 million Americans develop presbyopia usually in their 40's. Some individuals will develop presbyopia earlier due to diabetes or a family history of eye disease. One of the largest problems eye doctors face is convincing their patients to use their bifocals. Several people simply do not like to admit they need bifocals and often refuse to wear them in public situations. Laser eye surgery and bifocal contacts may be the answer for individuals that have problems with bifocal glasses. If you start noticing you are having difficulty focusing on close-up objects like a newspaper or map, contact your doctor for an eye exam.