Prisms can change the direction of parallel light rays. The optical strength of a prism is specified in prism diopters. Prism lenses can be combined with spherical and toric lenses. When prescribing eyeglasses, the ophthalmologist specifies the strength and the position of the base of the prism. Prism lenses are used to correct heterophoria (latent strabismus) and ocular muscle palsies, and in preparation for surgery to correct strabismus.

H A 1 diopter prism deflects a ray of light 1 cm at a distance of 1 m from the base of the prism.

Stretch Marks

Stretch Marks

Stretch Marks Prevention and Treatment. Learn What Exactly Are Stretch Marks And How Can They Be Treated. MP3 Audio included for your PC or IPod.

Get My Free Ebook and Audio

Post a comment