A corrective lens is a lens worn in front of or on the eye, mainly used to treat refractive errors such as myopia, hyperopia, astigmatism and presbyopia. Corrective lenses are designed to help your eyes to focus light properly onto your retina so that you can see clearly. This is done by bending the light rays (before they enter the eye) to the degree required by your given condition.
Glasses are corrective lenses that are worn on the face a short distance in front of the eye. There are several types of glasses, primarily:
- Monofocal – This type of lens has one focal point. This allows the wearer to either see things near or far.
- Bifocal – This lens is divided into two segments which offers distance viewing on the top and near vision on the smaller lower segment. You can see visible lines depicting the division of sight distance.
- Trifocal – These lenses allow three different visions: far, middle and near.
- Progressive – This lens offers the same functionality of a bifocal and trifocal lens but allows smoother transition between the focal points. No visible line separates the different prescriptions.
These corrective lenses are worn directly on the surface of the eye. Contact lenses come in the following types:
- Disposable – These are worn once and discarded at the end of a day.
- Daily Wear – These lenses can be worn only during the day and placed in a sterile solution at night.
- Extended Wear – These can usually be worn up to seven nights without removal.
- Bifocal – This type of contact provides near and far vision in one lens.
- Rigid Gas Permeable (RGP) – This is a hard lens, providing clearer vision for certain patients.
- Toric – This type can provide better vision for patients with astigmatism.