Types of contact lenses:By design

A spherical contact lens is one in which both the inner and outer optical surfaces are portions of a sphere. A toric lens in cheap eyeglasses is one in which either or both of the optical surfaces have the effect of a cylindrical lens, usually in combination with the effect of a spherical lens. Myopic (nearsighted) and hypermetropic (farsighted) people who also have astigmatism and who have been told they are not suitable for regular contact lenses may be able to use toric lenses. If one eye has astigmatism and the other does not, the patient may be told to use a spherical lens in one eye and a toric lens in the other. Toric lenses are made from the same materials as regular contact lenses but have a few extra characteristics than other glasses like plastic frames They correct for both spherical and cylindrical aberration.
They may have a specific ‘top’ and ‘bottom’, as they are not symmetrical around their centre and must not be rotated. Lenses not in metal frames must be designed to maintain their orientation regardless of eye movement. Often lenses are thicker at the bottom and this thicker zone is pushed down by the upper eyelid during blinking to allow the lens to rotate into the correct position (with this thicker zone at the 6 o’clock position on the eye). Toric lenses are usually marked with tiny striations to assist their fitting.

They are usually more expensive to produce than non-toric lenses in discount eyeglasses ; therefore they are usually meant for extended wear. The first disposable toric lenses were introduced in 2000 by Vistakon.
Like eyeglasses, contact lenses and sunglasses online can have one (single vision) or more (multifocal) focal points.

For correction of presbyopia or accommodative insufficiency multifocal contact lenses are almost always used; however, single vision lenses may also be used in a process known as monovision[32]: single vision lenses are used to correct one eye’s far vision and the other eye’s near vision. Alternatively, a person may wear single vision contact lenses to improve distance vision and reading glasses to improve near vision.

Rigid gas permeable bifocal contact lenses most commonly have a small lens on the bottom for the near correction, when the eyes are lowered to read, this lens comes into the optical path. RGPs must translate (move vertically) to work properly, and thus the gaze of the eye can change from the near to the distant sections, much like bifocal eyeglasses.

Multifocal soft contact lenses are more complex to manufacture and require more skill to fit. All soft bifocal contact lenses are considered “simultaneous vision” because both far and near vision corrections are presented simultaneously to the retina, regardless of the position of the eye. Of course, only one correction is correct, the incorrect correction causes blur. Commonly these are designed with distance correction in the center of the lens and near correction in the periphery, or vice versa.