Spherical Equivalent
The spherical power whose mean is equal to the sphero-cylindrical prescription.
Prescription
Spherical equivalent
−5.00 D
From −4.00 −2.00 × 180°
Calculation
- 01Input: −4.00 −2.00 × 180°
- 02Formula: SE = Sphere + Cylinder / 2
- 03SE = −4.00 + (−2.00 / 2)
- 04SE = −4.00 + (−1.00)
- 05SE = −5.00 D
Calculated result only. Verify the final power with over-refraction before dispensing a spherical lens for an astigmatic eye.
Formula
- 01SE = Sphere + Cylinder / 2
Clinical application
Limitations
Used for spherical soft lens fitting, cycloplegic comparison and trial lens selection. The spherical equivalent does not correct astigmatism — residual cylinder remains uncorrected and visual acuity may be reduced.
OptiX Pro provides mathematical calculations, reference information, and fitting assistance. It does not replace professional clinical examination, manufacturer fitting guidelines, or professional judgement. Contact lens selection and prescription must be clinically verified.