Contact to Glasses Prescription Converter
Convert your contact lens prescription to glasses prescription accurately. Enter your contact lens prescription details below for a precise conversion.
Right Eye (OD)
Left Eye (OS)
Understanding Contact Lens to Glasses Prescription Conversion
Converting between contact lens and glasses prescriptions is important because these two types of vision correction sit at different distances from your eye. Understanding the differences and conversion process helps ensure you get the correct prescription strength.
Key Differences Between Contact and Glasses Prescriptions
| Factor | Contact Lenses | Glasses |
|---|---|---|
| Distance from Eye | Directly on cornea | About 12mm from eye |
| Power Adjustment | Base prescription | Adjusted for vertex distance |
| Astigmatism Correction | Lens rotates with eye | Fixed in frame |
Prescription Components Explained
Understanding Your Prescription Values
| Component | What It Means | Typical Range |
|---|---|---|
| Sphere (SPH) | Overall vision correction power | -20.00 to +20.00 |
| Cylinder (CYL) | Astigmatism correction | -4.00 to +4.00 |
| Axis | Astigmatism orientation | 0 to 180 degrees |
Vertex Distance Compensation
The main difference between contact and glasses prescriptions is due to vertex distance - the space between your eye and the lens. This becomes more significant with stronger prescriptions.
| Contact Lens Power | Approximate Glasses Power | Difference |
|---|---|---|
| -2.00 | -2.00 | Minimal |
| -4.00 | -4.25 | 0.25D |
| -6.00 | -6.50 | 0.50D |
| -8.00 | -9.00 | 1.00D |
Signs You Need a Prescription Update
- Frequent headaches or eye strain
- Blurred or fuzzy vision
- Difficulty focusing between near and far objects
- Squinting to see clearly
- Eye fatigue during computer use
Frequently Asked Questions
Why are my contact and glasses prescriptions different?
Contact lenses sit directly on your eye, while glasses sit about 12mm away. This distance difference means the prescriptions need to be adjusted, especially for stronger prescriptions. This is called vertex distance compensation.
Can I use my glasses prescription for contacts?
No, you should never use a glasses prescription for contacts or vice versa without proper conversion. Contact lenses require additional measurements like base curve and diameter that aren't part of a glasses prescription.
How often should I update my prescription?
It's recommended to have your eyes examined and prescription updated:
- Every 1-2 years for adults with stable vision
- Annually for children and teenagers
- More frequently if you notice vision changes
- As recommended by your eye care professional
Why does the axis number matter?
The axis number (0-180 degrees) indicates the orientation of astigmatism correction. This number is crucial for proper vision correction and must be precise in both contacts and glasses.
Important Notes About Prescription Conversion
- This converter provides an estimate only - always consult your eye care professional for exact prescriptions
- Additional measurements are needed for proper contact lens fitting
- Some eye conditions may require special consideration
- Regular eye exams are essential for eye health
Understanding Eye Care Professional Roles
| Professional | Services | When to Visit |
|---|---|---|
| Optometrist | Vision tests, prescriptions, basic eye health | Regular check-ups, vision changes |
| Ophthalmologist | Medical eye care, surgery, complex conditions | Eye diseases, specialized treatment |
| Optician | Fitting glasses and contacts | After receiving prescription |