Our eyes allow us to see the world around us by taking the light rays that enter the pupil and bringing them into focus on the retina. In low light conditions like night-light driving the pupil dilates to allow more light to enter. When this occurs, rays passing through the outer edges of the pupil may be refracted to a greater degree than the central rays resulting in loss of focus. This is called spherical aberration.

Spherical aberration is a very common condition that may cause patients to experience blurred vision, halos or glare, especially in low light conditions.

Not all contact lenses compensate for spherical aberration; in fact some spherical contact lenses do not reduce spherical aberration effectively across all powers and in some cases may make it worse.

Bausch + Lomb PureVision2 HD contact lenses with high-definition optics are designed to reduce spherical aberration across a broad range of available powers and the halos, glare, and blur that can be associated with it.

Utilizing aspherical lens surfaces to control how the light reaches the retina, these advanced optical designs help ensure patients enjoy incredible crisp and clear vision - even in low light.
For the astigmatic eye the refractive correction requires compensation in two power meridians.