If you struggle to see objects up close and far away, bifocal lenses may work for you. Bifocal lenses combine two prescriptions into one, allowing you to smoothly see both near and far. They're especially helpful for people with myopia (nearsightedness) who develop presbyopia (farsightedness) as they age.
What Are Bifocal Lenses Used For?
Bifocals correct near and farsightedness so that you can view items at a distance and up close without switching between different pairs of glasses. You look through different parts of the lenses, depending on whether you're focused on faraway or close-up objects.
Invented by Benjamin Franklin in the 18th century, these lenses combine two prescriptions into a single lens, allowing clear vision across varying distances. Bifocal glasses are especially beneficial for people who face difficulty seeing faraway objects and experience presbyopia as they age.
Material Used in Bifocal Lenses
Lens materials can affect your eyewear's durability. They can be heavy or more fragile, or they can offer a good balance of durability, weight and clarity, which makes them suitable for everyday wear. Here's a look at your options:
- Standard plastic lenses: Plastic lenses, also called CR-39 lenses, are the most widely used material because they are lightweight and can be treated with various coatings, like scratch-resistant or anti-glare coatings. They are also affordable to produce, making them a cost-effective option for most wearers.
- Polycarbonate: Polycarbonate lenses are made from durable, impact-resistant plastic. They're fantastic if you lead an active lifestyle or need protective eyewear. Most are naturally UV-protective.
- Trivex: Trivex combines the best qualities of polycarbonate lenses, like impact resistance, with superior optical clarity. Trivex lenses are lighter than polycarbonate options, which makes them ideal for extended wear.
- Glass: Glass lenses are naturally more resistant to scratches and provide excellent clarity. However, they are heavier than plastic, so many wearers find them uncomfortable to wear all day. These lenses are also more prone to breaking or shattering upon impact, so if you're always losing your glasses case, glass lenses might not be the best option.
Different Types of Bifocal Lenses
Although all bifocals have two prescriptions in one lens, their designs differ. Common types of bifocal lenses include:
- Flat top: Flat top bifocals, also known as D-segment or straight-top bifocals, are a popular design. The bifocal section is shaped like a capital letter D, with the flat side facing up.
- Round segment: These designs have a curved, circular segment you can look through to see up-close objects.
- Blended: Blended bifocals are designed to minimize the visible line between distance and near-vision areas. The transition between the two is smooth and nearly invisible, giving the appearance of a single-vision lens.
- Ribbon segment: This design features a narrow, horizontal strip to help you see nearby objects. The strip runs across the bottom part of the lens, creating a "ribbon" effect.
- Executive: Executive lenses, also known as e-style or Franklin bifocals, follow Benjamin Franklin's original design. A near-vision segment covers the entire bottom half of the lens.
Bifocals vs. Progressive Lenses
Progressive lenses are multifocal lenses that provide a smooth transition between distance, mid-range and near-vision zones. They're similar to blended bifocals in that there is no noticeable distinction between the different zones. They are great if you need greater vision correction or often switch back and forth between activities requiring near and far vision. Bifocals are ideal if you want a clearer boundary between prescriptions.
How to Read Your Bifocals Prescription
When you receive your bifocal lens prescription, it might look like a confusing jumble of numbers and abbreviations. However, each part ensures your lenses are suited to your needs. During an eye exam, your doctor will assess your overall eye health by conducting tests for visual acuity and eye coordination. After the exam, your doctor will write a corresponding prescription. Some details you'll find on your prescription include:
- Sphere (SPH): This value indicates the lens power needed to correct nearsightedness or farsightedness. A positive number corrects farsightedness, while a negative number corrects nearsightedness.
- Cylinder (CYL): The cylinder value represents the amount of lens power needed to correct astigmatism, a common condition in which the eye's shape causes blurred or distorted vision.
- Axis: The axis is a number between 0 and 180 degrees that indicates the orientation of astigmatism. It tells the lens manufacturer where to place the cylindrical correction.
- Add power (ADD): The ADD represents the additional lens power needed for reading or other close-up tasks. This value is added to the sphere power to give you a clear near vision.
Customization Options
Modern bifocals can be customized according to lens material, segment shape and size to suit your visual needs and lifestyle. This allows for a more comfortable and effective vision correction experience. Some of your customization options include:
- Anti-reflective coatings: Anti-reflective (AR) coatings help reduce glare from lights and screens. With AR coatings, you may experience less eye strain and clearer vision, especially when driving or working on a computer.
- High-index lenses: High-index lenses are made from materials that bend light better, which allows them to be thinner and lighter than standard lenses. They are designed for people with strong prescriptions and are more comfortable to wear.
- Transition lenses: Transition lenses adjust their tint based on the amount of UV light exposure. They dim in bright sunlight and clear up indoors. This dual effect reduces the need to switch between regular glasses and sunglasses.
Wearing Bifocals
You can wear your bifocals all the time. However, while most lenses are designed and prescribed for everyday use, first-time wearers might encounter a brief adjustment period. You might experience difficulty judging distances or moving your eyes between the segments. These issues should resolve within a week to a month as your eyes adapt to the new lenses.
Get Bifocals Today at Eyemart Express
Bifocals are a convenient way for you to continue doing the tasks you love while keeping your vision needs in check. The advances in lens technology and design make for a comfortable and stylish experience.
If you experience both nearsightedness and farsightedness, bifocals might be the perfect option for you. At Eyemart Express, we offer a wide range of bifocal lenses. We use durable polycarbonate and lightweight Trivex to ensure the ultimate comfort. Visit a store near you for affordable, quality lenses in a blink. Enjoy the benefits of clear vision with Eyemart Express!
