Spherical Equivalent Calculator

Dual eye SE with classification, anisometropia check, and CL candidacy

SE = Sphere + (Cylinder ÷ 2)Axis does not affect SE — included for complete Rx context

OD — Right Eye

Sphere (D)

Cylinder (D)

Axis °

Original Rx

-2.00 / -1.00 × 180°

SE Equivalent

-2.50 D sph

Spherical Equivalent

-2.50 D

Classification

Low Myopia

CL Candidacy

Toric CL indicated — cylinder exceeds spherical CL threshold

Low Myopia

SE may be used for soft CL fitting if cylinder ≤0.75D. Distance correction beneficial.

Thin-lens magnification (approximate only): ~5.0% image size change at corneal plane. Actual magnification depends on vertex distance, base curve, CT, and index.

OS — Left Eye

Sphere (D)

Cylinder (D)

Axis °

Original Rx

-1.50 / -0.75 × 90°

SE Equivalent

-1.88 D sph

Spherical Equivalent

-1.88 D

Classification

Low Myopia

CL Candidacy

Borderline — spherical SE may be acceptable, toric preferred

Low Myopia

SE may be used for soft CL fitting if cylinder ≤0.75D. Distance correction beneficial.

Thin-lens magnification (approximate only): ~3.8% image size change at corneal plane. Actual magnification depends on vertex distance, base curve, CT, and index.

Anisometropia (SE difference): 0.63D

Minimal — no significant anisometropia

Full Summary

Eye	Original Rx	SE	Classification	CL Candidacy
OD	-2.00 / -1.00 × 180°	-2.50 D	Low Myopia	Toric CL indicated
OS	-1.50 / -0.75 × 90°	-1.88 D	Low Myopia	Borderline

What is Spherical Equivalent?

SE represents the average refractive power across all meridians by converting an astigmatic prescription to its spherical approximation. It collapses the toric Rx into a single number useful for classification and screening — but loses cylinder information.

When SE Is Clinically Appropriate

SE is used for: soft contact lens fitting (low cylinder), refractive surgery screening, epidemiological myopia classification, estimating aniseikonia risk in anisometropia, and approximating overall blur circle when cylinder is low.