If you wear a moderate or strong prescription, lens thickness affects both comfort and appearance. At CV Optical in San Francisco, we offer 1.60 and 1.67 high index lenses designed to reduce edge thickness while maintaining optical clarity.

Every pair is measured and fitted in person to ensure precision.

What Are High Index Lenses?

High index lenses are made from materials with a higher refractive index, meaning they bend light more efficiently. Because they bend light more effectively, less material is needed to achieve the same prescription power.

The result:

     ✔️ Thinner lenses
     ✔️ Lighter weight
     ✔️ Improved cosmetic appearance

We offer:

• 1.60 High Index

• 1.67 High Index

• Polycarbonate (1.59)

Understanding Refractive Index

The refractive index measures how efficiently a lens material bends light.

• Polycarbonate: 1.59

• High Index 1.60

• High Index 1.67

The higher the refractive index, the thinner the lens can be for stronger prescriptions.

Prescription Examples: Real Thickness Differences

-2.00 Prescription

1.60 provides mild thinning. Polycarbonate also works well for durability.

-4.50 Prescription

1.67 significantly reduces edge thickness compared to polycarbonate or 1.60.

-6.00 Prescription

1.67 is strongly recommended to reduce heavy edges and improve appearance.

-8.00 Prescription

1.67 combined with a smaller frame dramatically reduces thickness compared to standard plastic.

Edge Thickness Explained

For minus prescriptions, lenses are thinner in the center and thicker at the edges.

Edge thickness depends on:

• Prescription strength

• Frame width

• Lens diameter

• Pupillary distance

• Vertex distance (distance between lens and eye)

Larger frames increase edge thickness dramatically.

Choosing the right frame size can reduce thickness as much as upgrading the lens material.

Frame Size Impact on Final Appearance

Example:

• -6.00 in a 56mm wide frame → noticeable thick edges

• -6.00 in a 48mm frame → significantly thinner appearance

Frame selection is part of professional lens planning.

Aspheric Design: Cosmetic Improvement

Many 1.67 high index lenses use aspheric design, which flattens the front curve of the lens.

Benefits:

• Reduces “bulging” effect

• Minimizes magnification distortion

• Creates slimmer side profile

Aspheric designs improve both cosmetics and optical performance.

Abbe Value & Optical Clarity

The Abbe value measures how much chromatic aberration (color fringing) a material produces.

• Polycarbonate: Lower Abbe value

• 1.60: Balanced clarity

• 1.67: Slightly lower than 1.60 but thinner

For many prescriptions, 1.67 provides the best balance between thinness and visual clarity.

Polycarbonate vs High Index

Polycarbonate

Best for:

• Impact resistance

• Children

• Rimless or drill mount frames

Pros:

• Lightweight

• Extremely durable

Cons:

• Not as thin as 1.67

• Lower optical clarity compared to 1.60

1.60 High Index

Best for:

• -2.00 to -4.00 prescriptions

• Moderate thinning needs

1.67 High Index

Best for:

• Prescriptions stronger than -4.00

• Cosmetic edge reduction

• Professional appearance

Why Professional Measurement Matters

Even the best lens material performs poorly if improperly measured.

We measure:

• Pupillary distance

• Fitting height

• Pantoscopic tilt

• Vertex distance

These adjustments ensure clarity, comfort, and proper alignment.

Can You Put High Index Lenses in Old Frames?

Yes — if the frame is structurally sound and appropriately sized for your prescription.

However, smaller frames often produce better cosmetic results.

Book a Lens Consultation in San Francisco

All measurements are performed in person at CV Optical in San Francisco’s Financial District.

If you want thinner lenses without compromising clarity, schedule a lens consultation today.