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Product Introduction
The Timeless Standard: Reliable Multi-Distance Vision
While modern progressive lenses have become popular, the Flat-Top Bi-Focal remains a vital and highly effective tool for a large segment of the population. For many users—particularly seniors, those with specific occupational needs, or patients who struggle with the peripheral distortion of progressives—the clarity and stability of a classic bifocal are unmatched. Our Flat-Top Bi-Focal Classic Lenses (also known as D-Seg lenses) provide a definitive, wide area for reading that is physically separated from the distance zone. This design eliminates the "corridor" of a progressive lens, providing the wearer with a much larger and more consistent field of view for near tasks such as reading a newspaper, sewing, or working on fine mechanical parts.
The "Flat-Top" refers to the shape of the near-vision segment, which is molded with a straight upper edge. This is mathematically designed to place the optical center of the reading zone as close to the top as possible, minimizing the "image jump" that occurs when the eye moves from distance to near vision. Our classic series is manufactured using high-precision casting molds that produce a nearly seamless "ledge." While the segment is visible, the transition is physically smooth, reducing the aesthetic bulk of older bifocal designs. We offer these in various segment widths—28mm for general use and 35mm for those who require an extra-wide reading field. Available in a wide range of materials from standard 1.499 resin to 1.67 high-index, these lenses can be customized with all modern coatings, including anti-reflective, blue-cut, and photochromic. For the dispenser, the Flat-Top Bi-Focal is a reliable, high-success-rate product that offers instant patient satisfaction with virtually no adaptation period. It remains the gold standard for anyone who values a wide, stable reading zone and clear, uncompromised distance vision.
Technical Specifications
| Segment Type | Flat-Top 28 (D28) / Flat-Top 35 (D35) |
| Addition Range | +1.00D to +4.00D (0.25 steps) |
| Material Indices | 1.499, 1.56, 1.60, 1.67 Resin |
| Segment Position | Standard or Custom Inset |
| Abbe Value | 36 - 58 (Material Dependent) |
| Coating | Hard Coat / HMC / Super Hydrophobic |
| UV Protection | Built-in UV380 or UV400 |
Technological Highlights: Premium Monomers and Coating Integrity
- High-Purity Monomer Selection: We exclusively use high-performance monomers (e.g., MR-series) to achieve superior tensile strength and optical purity, resulting in excellent clarity and minimal risk of yellowing over time.
- Precision Liquid Casting Process: The lenses are produced via a controlled liquid casting method that ensures uniform material density and refractive index consistency across the entire blank, which is critical for accurate therapeutic power zones.
- Advanced Vacuum Multi-Coating (SHMC): Coatings are applied in a high-vacuum chamber, using multiple layers of metallic oxides to create a durable, anti-reflective stack. This process guarantees maximum light transmission and minimal glare.
- Thermal Curing Optimization: A slow and precise thermal curing cycle is employed to maximize the material’s resistance to internal stress, ensuring the finished lens remains stable and optically perfect under varying temperature conditions.
- Integrated Peripheral Defocus Geometry: The therapeutic design is engineered into the mold itself for cast lenses, or applied via digital surfacing for semi-finished blanks, guaranteeing the accuracy and consistency of the myopia control zone geometry.
Primary Applications
- Traditional Presbyopes: Patients who prefer the stability of a bifocal.
- Low Vision Support: Provides a large, high-power reading area.
- Post-Op Patients: Often easier to use than progressives after eye surgery.
- Specific Hobbies: Ideal for stamp collecting, watch repair, or detail-heavy crafts.
Key Advantages
- Zero Peripheral Distortion: Clear vision all the way to the lens edge.
- Instant Adaptation: No "learning curve" compared to progressive lenses.
- Wide Reading Zone: Significantly larger near-vision area than most progressives.
- Cost-Effective: High performance at a more accessible price point.
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Customization
Customized For Your
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Complete Customization Capability
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Professional Lens Architecture
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Functional Coating Customization
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Digital Rx Customization
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Branding & Packaging
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Delivery & Support
Frequently Asked Questions (FAQ)
- Q: Why choose this over a progressive lens?
- A: It offers a much wider and more stable reading area with no side distortion.
- Q: Is there an "Image Jump"?
- A: There is a slight jump at the line, but it is minimized by our precision grinding.
- Q: What does "D-Seg" mean?
- A: It refers to the D-shaped reading segment in the lower part of the lens.
- Q: Can I get them in a thin material?
- A: Yes, we offer Flat-Tops in 1.60 and 1.67 high-index resins.
- Q: Are they good for driving?
- A: Yes, the upper part provides a completely clear view of the road.
- Q: Can I have them as transition lenses?
- A: Yes, photochromic Flat-Tops are available in Grey and Brown.
- Q: Is the line very visible?
- A: The line is visible, but it is the hallmark of the classic bifocal design.
- Q: Do they block UV?
- A: Yes, all our resin bifocals include 100% UV400 protection.
- Q: Are they suitable for computer work?
- A: They are great for reading, but for computer screens, the height must be measured carefully.
- Q: Are they easy to clean?
- A: Yes, the SHMC coating makes them resistant to smudges and water.
Payment & Shipping
Flexible T/T, L/C, or Credit terms. Available as semi-finished blanks for labs or finished RX for retailers. Global shipping with 7-10 day lead times for stock items.
Business Information
| MOQ | 200 Pairs (Stock) / 1 Pair (RX) |
| Lead Time | 7 - 12 Days |
| Certifications | CE, FDA, ISO9001 |
