MICHAEL / Eyewear Answers & Calculators
How do I hide thick edges on strong minus (-5.00 to -14.00 D) glasses?
Direct answer:Pick a full-rim cellulose acetate frame with a 40 to 44 mm lens width whose geometric center sits within 3 mm of your pupillary distance, then pair it with 1.67 Thin High-Index (US$55/pair Single Vision Clear) for -4.50 to -6.50 D or 1.74 Ultra High-Index (US$100/pair) past -6.75 D.
Rx Lens Index & Edge Thickness Visualizer (1.56 to 1.74)
Slide your Sphere (SPH) and Astigmatism (CYL) dioptre powers to compare relative lens profile thickness, weight savings and confirmed package pricing.
The Decentration Formula Bench Opticians Check First
Many shoppers pay US$100+ for 1.74 Ultra High-Index lenses and still end up with thick outer edges because the frame is too wide for their pupillary distance (PD). Concave minus lenses are thinnest at your pupil (~1.1 to 1.5 mm) and gain thickness with every millimetre of cutout radius. Before choosing a frame, calculate per-eye decentration in millimetres:
Decentration per eye = (Lens Width + Bridge Width - Binocular PD) ÷ 2
| MICHAEL Frame Example | Stamped Size (Lens × Bridge) | Decentration on 62 mm PD | Rim Wall Coverage | Side-Profile Result |
|---|---|---|---|---|
| EM23218 (US$25.70) | 42 × 24 mm | 2.0 mm per eye | ~4 mm full-rim acetate | Temporal bevel sits nearly flush inside the acetate eyewire. |
| EM23107 (US$25.70) | 40 × 28 mm | 3.0 mm per eye | ~4 mm full-rim acetate | Smallest 40 mm aperture cuts outer edge diameter dramatically. |
| FT2403 Brown/Black (US$25.70) | 44 × 27 mm | 4.5 mm per eye | ~4 mm full-rim acetate | Clean everyday balance for -5.00 to -8.00 D in 1.67 or 1.74. |
| Oversized Wire Frame (54 × 20 mm) | 54 × 20 mm | 6.0 mm + wide diagonal | ~1.2 mm thin metal rim | 3 to 5 mm of exposed minus edge projects past the back of the wire. |
Four Frame Rules That Hide Concentric Minus Rings
- Favour round or soft oval lenses over sharp cat-eye corners: Lens blanks are cut along their longest diagonal. Sharp upper-outer corners sit farthest from your pupil and accumulate the thickest glass-like edge.
- Use 4 mm cellulose acetate rims to mask the bevel: Full-rim models in the US$25.70 EM Acetate series wrap ~4 mm of hand-polished cellulose acetate around the lens perimeter, hiding the white ground bevel that thin metal wires leave exposed.
- Keep included anti-reflective coating on high-index resin: 1.67 and 1.74 resins bend light more sharply and create visible concentric internal "power rings" if left uncoated. Every MICHAEL lens pair includes green anti-reflective and scratch-hardened base coating at US$0 extra.
- Enter exact Dual Monocular PD: At
-8.00 D, a 2 mm PD error shifts the optical center horizontally and adds uneven temporal thickness on one side while inducing prism strain.
Follow-Up Questions Buyers Ask
What is the strongest nearsighted prescription MICHAEL Optical makes online?+
Single Vision 1.74 Ultra High-Index Clear, Blue-Light and Photochromic packages support Sphere (SPH) powers down to -20.00 D (and up to +16.00 D in Clear), with astigmatism cylinder (CYL) included at US$0 extra down to -6.00 D on Clear and Blue-Light lenses.
Why does FT2403 Clear fit differently than FT2403 Brown or Black for strong prescriptions?+
MICHAEL FT2403 uses two distinct mould sizes by colourway: Brown and Black measure 44 x 27 x 142 mm (compact, ideal for strong minus lenses), whereas Crystal Clear measures 52 x 22 x 143 mm. Always pick Brown or Black on FT2403 when minimizing edge thickness.
Does frame colour affect how noticeable high-myopia "power rings" look from the front?+
Yes. Dark tortoise, espresso brown and solid black acetate rims absorb light scattered inside the ground lens edge, whereas crystal-clear transparent rims let edge reflections pass through.
Clinical & Regulatory References
- Nearsightedness (Myopia): Optical Correction & Concave Lens Geometry ↗ (NIH National Eye Institute (NEI)) Explains how concave minus lenses diverge incoming light rays and thicken progressively away from the optical center.
- Eyeglasses: What You Need to Know About High-Index Lenses & Coatings ↗ (American Academy of Ophthalmology (AAO)) Clinical guidance on high-index plastic lenses for strong prescriptions and anti-reflective surface treatments.