Glasses → Contact Lens Conversion
Vertex-corrected contact lens equivalent. Each principal meridian is converted separately — a sphero-cylinder is never treated as a single spherical value.
Right eye · OD
Contact lens Rx
−7.25 −1.25 × 180°
Exact −7.30 −1.23 × 180° · SE −7.87 D
High-power conversion: verify final lens power with manufacturer fitting guidelines and over-refraction.
- 01Spectacle Rx: −8.00 −1.50 × 180° at 12 mm
- 02Meridian 1 = −8.00 D → −7.3000 D
- 03Meridian 2 = −9.50 D → −8.5300 D
- 04d = 0.012 m, F_CL = F / (1 − d·F)
- 05CL cylinder = −8.5300 − −7.3000 = −1.2300 D
- 06Rounded to 0.25 D: −7.25 −1.25 × 180°
Left eye · OS
Contact lens Rx
−7.00 −0.75 × 175°
Exact −6.88 −0.83 × 175° · SE −7.37 D
High-power conversion: verify final lens power with manufacturer fitting guidelines and over-refraction.
- 01Spectacle Rx: −7.50 −1.00 × 175° at 12 mm
- 02Meridian 1 = −7.50 D → −6.8800 D
- 03Meridian 2 = −8.50 D → −7.7100 D
- 04d = 0.012 m, F_CL = F / (1 − d·F)
- 05CL cylinder = −7.7100 − −6.8800 = −0.8300 D
- 06Rounded to 0.25 D: −7.00 −0.75 × 175°
Clinical verification required
Calculated contact lens powers are a starting point. Confirm the final power with over-refraction and the manufacturer's fitting guide.
Formula
- 01F_CL = F_spec / (1 − d × F_spec)
- 02d = vertex distance in metres (default 12 mm)
- 03Meridian 1 = Sphere
- 04Meridian 2 = Sphere + Cylinder
- 05CL Cyl = Meridian 2' − Meridian 1'
Clinical note
Fit, movement, centration, comfort, corneal physiology, tear film and over-refraction must be assessed clinically. Axis is carried across unchanged; residual astigmatism and lens rotation are assessed on-eye.
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.