Glasses to Contact Lens Prescription Converter
Convert your glasses prescription to contact lens prescription by entering your glasses prescription details below. Please note that this is only an estimate - always consult your eye care professional for the final prescription.
Right Eye (OD)
Left Eye (OS)
List of the Best Contact Lens Solution:
Understanding Glasses and Contact Lens Prescriptions
While glasses and contact lens prescriptions contain similar information, they are not identical. Contact lenses sit directly on your eye, while glasses sit about 12mm away from your eye, which affects the final prescription values.
Key Prescription Components
| Component | Abbreviation | What It Means |
|---|---|---|
| Sphere | SPH | Corrects nearsightedness (-) or farsightedness (+) |
| Cylinder | CYL | Corrects astigmatism |
| Axis | AX | Orientation of astigmatism correction (0-180 degrees) |
Differences Between Glasses and Contact Lens Prescriptions
| Feature | Glasses | Contact Lenses |
|---|---|---|
| Distance from eye | ~12mm | Directly on eye |
| Power adjustment | Base prescription | Slightly lower power needed |
| Astigmatism correction | More precise | May be rounded to nearest available power |
| Additional measurements | PD (Pupillary Distance) | Base curve, diameter |
How the Conversion Works
Converting from glasses to contact lens prescription involves several adjustments:
- Vertex distance compensation (distance between glasses and eye)
- Power adjustment for direct eye contact
- Astigmatism compensation if applicable
- Rounding to available contact lens powers
Power Adjustment Guidelines
| Glasses Prescription | Approximate Contact Lens Power | Typical Adjustment |
|---|---|---|
| -2.00 to +2.00 | Same as glasses | No adjustment needed |
| -2.25 to -4.00 | Slightly less minus | +0.25D |
| -4.25 to -8.00 | Less minus | +0.50D to +0.75D |
| Over -8.00 | Significantly less minus | +1.00D or more |
Important Considerations
- A contact lens prescription requires additional measurements not found in glasses prescriptions, including:
- Base curve (BC): Determines how the lens fits on your eye
- Diameter (DIA): The overall size of the contact lens
- Brand and material: Specific to your eye's needs
- Not all glasses prescriptions can be directly converted to contact lenses
- High astigmatism may require special toric contact lenses
- Some eye conditions may prevent contact lens wear
Frequently Asked Questions
Why is my contact lens prescription different from my glasses?
Contact lenses sit directly on your eye, while glasses sit about 12mm away. This difference in distance requires an adjustment in the prescription power, especially for stronger prescriptions.
Can everyone wear contact lenses?
Not everyone can wear contact lenses. Certain eye conditions, severe dry eye, or allergies may make contact lens wear difficult or impossible. Consult your eye care professional to determine if you're a good candidate.
How accurate is this converter?
This converter provides an estimate based on standard conversion factors. However, your actual contact lens prescription may differ based on individual factors. Always get a professional fitting and prescription from an eye care provider.
Do I need a separate prescription for contacts?
Yes. In most countries, you need a separate, valid contact lens prescription to purchase contact lenses. This includes specific measurements and parameters that aren't part of a glasses prescription.
Care and Safety
Proper contact lens care is essential for eye health:
- Always wash hands before handling contact lenses
- Use fresh contact lens solution daily
- Never sleep in contact lenses unless specifically prescribed
- Replace contact lenses as scheduled
- Attend regular eye examinations
- Remove contacts immediately if you experience discomfort or redness
Important: This converter provides estimates only. A proper contact lens fitting by an eye care professional is required for a valid contact lens prescription. Different brands of contact lenses may require different parameters even for the same prescription.