What is the difference between a toric and a spherical contact lens?

What Is the Difference Between a Toric and a Spherical Contact Lens?

If your prescription includes a cylinder and axis value, you need a toric lens. Here is a clear explanation of the fundamental difference between toric and spherical lenses — and why the distinction matters.

Spherical Contact Lenses

A spherical contact lens has the same optical power across all meridians of the lens. It corrects myopia (nearsightedness) or hyperopia (farsightedness) — conditions where all light focuses in front of or behind the retina. The correction is the same in every direction, so the prescription only requires a sphere power (SPH).

What Is Astigmatism?

Astigmatism occurs when the cornea or lens has an irregular, rugby-ball-like curvature rather than being perfectly spherical. Light entering the eye focuses at different points depending on its angle — creating blurred or distorted vision at all distances. Because the optical irregularity is directional, correcting it requires different optical powers in different meridians, which a spherical lens cannot provide.

Toric Contact Lenses

A toric lens has two different curvatures built into the optical zone — one correcting sphere, one correcting astigmatism at a specific axis. Because this correction is directional, toric lenses need a stabilization mechanism to prevent rotation. Biofinity Toric uses Optimized Lens Geometry for this purpose. A toric prescription includes three parameters: sphere (SPH), cylinder (CYL), and axis.

If your contact lens prescription includes a cylinder (CYL) value, you have astigmatism and require a toric lens. Your eye care professional will determine whether your level of astigmatism requires toric correction and which lens is most appropriate.