1. What is Lens Thickness Calculation?

The lens thickness calculation determines the total thickness of eyeglass lenses by adding the sagittal depth (sag) to the minimum edge thickness. This is important for proper lens fitting and aesthetics.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( Sag \) — Sagittal depth of the lens (mm)
• \( Min\ Thickness \) — Minimum edge thickness required (mm)

Explanation: The total thickness is the sum of the lens curvature (sag) and the minimum thickness needed for structural integrity.

3. Importance of Lens Thickness

Details: Proper lens thickness ensures comfortable wear, proper fit in frames, and optimal optical performance. Thicker lenses may be needed for higher prescriptions.

4. Using the Calculator

Tips: Enter sagittal depth and minimum thickness in millimeters. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is sagittal depth (sag)?
A: Sag is the vertical depth of a lens curve, measured from the chord (straight line) to the arc of the curve.

Q2: How do I measure sagittal depth?
A: Sag can be measured with a sagometer or calculated based on lens curvature and diameter.

Q3: What's a typical minimum thickness?
A: Minimum thickness varies but is typically 1.0-2.0 mm for plastic lenses and 0.8-1.5 mm for high-index materials.

Q4: Does lens material affect thickness?
A: Yes, higher index materials can achieve the same optical power with less thickness.

Q5: Why is edge thickness important?
A: Proper edge thickness ensures durability and prevents chipping or cracking of lenses.