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Dual Strength Bifocal - The Card Shark
$79.95
How to Choose Your Strengths
Choosing your powers is easier than it sounds. Here’s a simple way to think about it:
Step 1 – Start with what you already wear.
If you use two pairs today — one for the computer and one for reading — those are the same two strengths you’ll use in your Dual-Strength lenses: computer power on top, reading power on the bottom.
If you currently wear just one pair of readers, use that strength as your bottom (reading) power.
Step 2 – Choose a milder power for the top.
The top of the lens is made for computer and mid-range (arm’s-length) vision, so it should be weaker than your reading strength — similar to your “computer pair” if you already use one.
Step 3 – Why the difference matters.
Dual-Strength lenses work best when the top is at least
1.00 diopter weaker than the bottom.
This creates a smooth, comfortable transition from computer distance to close-up reading — without eye strain.
Step 4 – Fine-tune for your daily habits.
If you spend more time on the computer than reading, choose a gentler top power for relaxed, sustained clarity.
Here are a few example combinations that follow the required 1.00 diopter difference and offer smooth dual-distance clarity:
| Your usual readers | Suggested top (computer) | Suggested bottom (reading) |
|---|---|---|
| +2.50 | +1.50 | +2.50 |
| +3.00 | +2.00 | +3.00 |
| +3.50 | +2.50 | +3.50 |
| +4.00 | +3.00 | +4.00 |
Dual-Strength Bifocals vs. Progressive Lenses
Progressive lenses may promise seamless vision, but for many readers, they come with trade-offs that affect comfort, safety, and cost.
Long adjustment period: Progressives often require weeks of adaptation and can cause dizziness, headaches, or eye strain.
Dual-Strength benefit: Two clearly defined zones mean little to no adjustment—your eyes know exactly where to look.
Reduced peripheral vision: The narrow vision corridor in progressives can limit side vision, which may feel unnatural or unsafe while walking or driving.
Dual-Strength benefit: Full peripheral clarity with no distortion or swim.
Higher cost: Progressives are often significantly more expensive due to complex lens technology.
Dual-Strength benefit: $79 with free shipping—clear, predictable pricing.
Frame limitations: Progressives require taller frames, reducing your style options.
Dual-Strength benefit: Over 40 frame styles in multiple sizes, colors, and shapes—no compromises.
Why Dual-Strength Bifocals Just Work
- • Two clearly defined magnification zones for natural, predictable vision
- • Comfortable clarity for reading, computer work, and everyday mid-distance
- • Designed for immediate comfort — no learning curve
- • Thoughtfully engineered for daily wear, all day long
We’ve been designing and perfecting reading glasses for over 30 years. Every Dual-Strength lens reflects decades of hands-on experience listening to customers, refining fit, and focusing on what truly makes glasses easy to wear.
You’ve chosen the frame style. Next, you’ll personalize your pair by selecting the frame color, frame width, and lens strengths that suit how you see and live.
Choose your color, width, and powers below to complete your pair ↓
- SKU:
- en4200dualbf
- Weight:
- 1.10 Ounces
Description
Sharp, bold, and built for readers who always play to win.
Everyday Vision with a Competitive Edge
Meet The Card Shark, a sleek rectangular frame designed for readers who appreciate clean lines, modern angles, and practical comfort. With its versatile sizing and lightweight build, this frame brings professional polish to your daily reading routine.
Whether you're scanning documents, multitasking at work, or enjoying your favorite book, this design delivers clarity and style in equal measure.
Seamless Clarity with Dual-Strength Bifocal Technology
DebSpecs’ dual-strength bifocal lenses make shifting between tasks effortless.
Upper Zone – Intermediate / Screen Vision
• Softer magnification for computer use, meetings, and mid-range viewing
• Reduces eye fatigue during extended screen time
Lower Zone – Near / Reading Vision
• Stronger magnification for up-close clarity
• Ideal for reading, crafting, fine details, labels, and paperwork
Smooth transitions – no visible line, no interruptions.
Lightweight Plastic with Everyday Comfort
• Sleek rectangular silhouette for modern versatility
• Lightweight plastic frame suitable for long hours of wear
• Comfortable temple design for a secure, stable fit
• Available in two size options to accommodate more face widths
Fit & Measurements
Lens Width: 53 mm or 56 mm
Bridge: 17 mm
Temple Length: 140 mm or 145 mm
Face Width:
• Average – 125 mm
• Wide – 131 mm
Shape: Rectangle
Materials: Plastic
Target Customer: Unisex
Available Colorways
• Shiny Tortoise – warm and classic
• Black – clean and timeless
• Cobalt Blue – bold and modern
• See Through (Crystal) – fresh, minimalist clarity
• Matte Gray with Black Arms – understated, sleek, and refined
Perfect For
• Professional, everyday, and casual wear
• Readers who want a lightweight but durable frame
• Switching between screens and reading tasks
• A modern, no-fuss rectangle look
Why “The Card Shark” Is a Smart Upgrade
• Sharp rectangular design with wide size availability
• Smooth dual-strength bifocal reading comfort
• Lightweight, durable, and office-friendly
• Five versatile color options
Shipping & Production Notes
Frames may require 3–5 business days for final finishing before shipment.
Downloads
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11 Reviews Write a Review
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Dual Strength Bifocal - The Card Shark
I would give these a 5 star rating except for one thing, and it's no ones fault. I need a 1.5 on top and a 2.75 on bottom, but no one seems to make that. So I got a 1.5 on top and a 2.5 on bottom, and unfortunately the .5 difference is very noticeable. Otherwise I really love these glasses. They're stylish and well made. Shipping was earlier than expected and the case included is great. If I can ever find someone to do a 1.5/2.75 I will gladly give them 5+ stars.
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Dual bifocal readers
I think if more people knew about these they would love them. They help my computer and also my paperwork become clear. I use a lower strength on the top and higher on lower and it works wonderfully
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Fantastic!
I’m an electrical engineer and spend much of my time switching my gaze between a large monitor and reading material on my desk, and since I am far-sighted, this means switching between two different strength reading glasses. For quite some time now I’ve looked for readers with different magnifications to no avail. I’ve tried “progressives” which have a very small field of view (an extreme case of foveated view), and can not tolerate this. I don’t remember how I stumbled on these card sharks, but I’m very glad I did; these are worth their weight in gold to me; no more swapping glasses repeatedly. Quality is fantastic as well. Good job Debbie Burke!!
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Dual Strength Bifocal
I spend a lot of time on computer while doing paperwork, Dual strength bifocals allowed me to stop having to switch glasses each time i went from cpu screen to paper documents. Great product that met my needs.
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Perfect for my needs
I am constantly struggling with the need for 2 different OTC readers. One for close up and one for my computer. My optometrist could only supply these with plain glass at the top and the 2 reading powers sharing the bottom half of the frame. Gave me headaches as the area I had to focus on was very thin. After much searching I found these. The Card Shark Dual Strength Bifocal is perfect. Top half is for reading my computer, the bottom half is for papers or phone or similar. So glad I found them. No more carrying around multiple reading glasses. the lens is of good quality, the frames are solid and the wider frame fits me head perfectly not leaaving me with imprints along my temple. These are a must have is you want simples dual power readers.
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dual strength bifocal
These glasses are great!! They provide a clear vision for both powers. The quality is excellent.