1. What is Spherical Equivalent?

The Spherical Equivalent (SE) is a way to simplify a sphero-cylindrical prescription into a single spherical value. It's calculated by adding half of the cylinder power to the sphere power. This calculator also adjusts for face shape to provide more personalized results.

2. How Does the Calculator Work?

The calculator uses the spherical equivalent formula with face shape adjustment:

Where:

• \( Sphere \) — Spherical component of the prescription (diopters)
• \( Cylinder \) — Cylindrical component of the prescription (diopters)
• Face shape adjustment — Small correction factor based on face shape

Explanation: The basic spherical equivalent is calculated first, then adjusted slightly based on face shape to account for how glasses sit differently on various face shapes.

3. Importance of Face Shape Consideration

Details: Different face shapes affect how glasses sit on the face, which can slightly impact the effective power of the lenses. This adjustment provides more personalized results.

4. Using the Calculator

Tips: Enter your exact sphere and cylinder values from your prescription, then select your face shape. The calculator will provide the adjusted spherical equivalent.

5. Frequently Asked Questions (FAQ)

Q1: When is spherical equivalent used?
A: SE is often used for contact lens prescriptions, refractive surgery planning, and when simplifying complex prescriptions.

Q2: How does face shape affect glasses?
A: Face shape affects the angle and position of glasses relative to the eyes, which can slightly change the effective power.

Q3: Is this calculator a substitute for professional advice?
A: No, always consult with your eye care professional for prescription decisions.

Q4: Why are the face shape adjustments so small?
A: The effect of face shape is subtle, typically less than 5% adjustment to maintain accuracy.

Q5: Can I use this for both plus and minus prescriptions?
A: Yes, the calculator works for both positive and negative sphere and cylinder values.