Iris-fixated intraocular lens Iris-fixated intraocular lens Iris-fixated phakic intraocular lens is an intraocular lens that is implanted surgically into the eye and fixated to the iris to correct myopia (nearsightedness). Early models were sutured to the iris with a stitch; the claw fixation method made iris stitching unnecessary. The iris-claw lens is fixated to the anterior iris surface by enclavation of a fold of iris tissue into the two diametrically opposed claws of the lens. The fixation sites are located in the midperiphery of the iris, which is immobile during pupillary movement. This lens was modified into a convex-concave design and manufactured as
Parallel projection central or perspective projection, in which the rays pass through a fixed point called the "center" or "viewpoint", as this point is moved towards infinity. Put differently, a parallel projection corresponds to a perspective projection with an infinite focal length (the distance between the lens and the focal point in photography) or "zoom". In parallel projections, lines that are parallel in three-dimensional space remain parallel in the two-dimensional projected image. A perspective projection of an object is often considered more realistic than a parallel projection, since it more closely resembles human vision and photography. However, parallel projections are popular in