Understanding Eye Prisms: How They Correct Vision Problems

Prisms are a special addition to corrective eyewear that assist in improving and correcting a patient's vision deficiencies.

Features

• Prisms are a type of lens with precise geometric configurations added to corrective eyewear to reflect or bend light in a particular way. These special additions to eyewear can also split light into different wavelengths and colors to provide more accurate vision.

Prescription Identification

• Eyewear prescriptions have standardized notations that can be interpreted worldwide: the first number indicates the level of near- or farsightedness, and an additional number that appears with a "^" symbol indicates prism correction, which may differ for each eye.

Binocular Dysfunction

• Some patients eyes' work differently from each other, impairing vision because they have different vision ability and vision deficiencies in each eye, called binocular dysfunction. Prisms correct binocular dysfunction to make the eyes work together as a team.

Peripheral Vision Loss

• Some eye conditions, such as glaucoma, lead to peripheral vision loss, which is when the visual field begins to narrow, sometimes leading to tunnel vision. Prisms are added to eyeglasses to expand the field of view for patients with peripheral vision loss.

Strabismus and Cranial Nerve Palsies

• Strabismus and cranial nerve palsies are similar conditions of the eyes looking in separate directions, which is often caused by diabetes but may also be caused by head injury, multiple sclerosis, meningitis, high blood pressure, a blockage in an artery or aneurysm. Prisms are used to help correct this type of vision abnormality.

Glasses and Contacts

• Typically, prisms are used in eyeglasses, but are now frequently used in contact lens prescriptions, as well. Whether prisms can be worn in contact lenses depends on the function and size of the prism required.