Acuvue Contact Lens Prescription Converter
This calculator helps convert your spectacle (glasses) prescription to an estimated contact lens prescription, primarily by adjusting for vertex distance. This is especially important for higher prescriptions where the distance between your glasses and your eye significantly impacts the required lens power.
Acuvue contact lenses, like all contact lenses, require a professional fitting by an eye care specialist. This tool provides an estimate and does not replace a comprehensive eye exam and contact lens fitting.
Enter the sphere power from your glasses prescription (e.g., -3.50, +2.00).
Enter the cylinder power for astigmatism (e.g., -0.75). Enter 0 if no astigmatism.
Enter the axis for astigmatism (e.g., 90, 180). Enter 0 if no astigmatism.
Typical vertex distance is 10-14mm. Consult your eye care professional if unsure.
Understanding Vertex Distance Compensation
When you wear glasses, the lenses sit a small distance away from your eyes. This distance is called the "vertex distance." Contact lenses, however, sit directly on the surface of your eye. For higher prescriptions (typically above +/- 4.00 Diopters), this difference in distance means that the power required for a contact lens will be different from your spectacle prescription.
The further a lens is from the eye, the more its effective power changes. For minus (nearsighted) prescriptions, the contact lens power will be weaker (closer to zero) than the glasses prescription. For plus (farsighted) prescriptions, the contact lens power will be stronger (further from zero) than the glasses prescription.
Acuvue Lens Parameters and Professional Fitting
Beyond the power adjustment, contact lenses also have other critical parameters:
- Base Curve (BC): This is the curvature of the back surface of the contact lens. It needs to match the curvature of your cornea for comfort, good vision, and eye health. Acuvue lenses typically come in a few standard base curves (e.g., 8.4mm, 8.8mm, 9.0mm), and your eye care professional will determine the best fit for your eye.
- Diameter (DIA): This is the overall width of the contact lens. It's crucial for proper centration and coverage of the cornea. Acuvue lenses also have specific diameters (e.g., 14.0mm, 14.2mm).
- Cylinder and Axis: For astigmatism, Acuvue offers toric lenses with specific cylinder powers and axes. While the sphere power is adjusted for vertex distance, the cylinder power and axis from your spectacle prescription are generally carried over directly to the contact lens prescription, as their vertex distance effect is less significant or handled differently in toric lens design.
It is crucial to understand that this calculator provides an estimated power for the spherical component only. A comprehensive eye examination and a professional contact lens fitting by an optometrist or ophthalmologist are absolutely essential. They will measure your eyes, assess your tear film, determine the precise base curve and diameter, and ensure the contact lenses fit properly, are comfortable, and provide optimal vision and eye health. They will also confirm the exact Acuvue product and parameters suitable for your individual needs.
Example Calculation
Let's say your spectacle prescription is Sphere -6.00 D, Cylinder -1.00 D, Axis 180 degrees, and your vertex distance is 12mm.
Using the formula for vertex distance compensation (Fc = Fs / (1 – d * Fs)):
- Spectacle Sphere (Fs) = -6.00 D
- Vertex Distance (d) = 12mm = 0.012 meters
- Calculated Contact Lens Sphere (Fc) = -6.00 / (1 – 0.012 * -6.00)
- Fc = -6.00 / (1 + 0.072)
- Fc = -6.00 / 1.072
- Fc ≈ -5.597 D
Therefore, the estimated contact lens sphere power would be approximately -5.60 D. The cylinder and axis would typically remain -1.00 D and 180 degrees, respectively, for a toric contact lens.
Your eye care professional would then select the closest available Acuvue lens power (e.g., -5.50 D or -5.75 D) and the appropriate base curve and diameter for your eyes.