contact lens

Last reviewed 01/2018

Contact lenses are usually recommended over spectacles. Image magnification is smaller - about 10% - visual acuity is good and there are no peripheral distortions. The degree of magnification is sufficiently small that they may allow image fusion if the other eye is phakic. Tolerance is often better than in other patients since the sensory supply to the cornea has been impaired by the corneal incision.

The main difficulty is the dexterity required to handle them. They are unsuitable for the elderly and for those with parkinsonism, rheumatoid arthritis, or mental retardation.

Different types of contact lenses have their individual nuances to consider. A hard lens moves over the cornea with each blink and allows the tear film behind to provide nutrition to the eye and neutralise astigmatism. The soft lens is slightly larger, more comfortable, and easier to handle but may induce corneal vascularisation and can only correct a limited degree of astigmatism - up to about 1.5 dioptres.

Permanent wear contact lenses have the major advantage of permitting continued wear through the day and night. However, many regard them to not be as safe as the other types.