Page 97 - The Book Pi in eye

Pi in eye

surgeon alters the shape of the cornea by making thin incisions
around it in a spoke like pattern. The incisions cause the central
portion of the cornea to flatten, treating myopia and astigmatism. RK
is not performed anymore.

Refract: To bend, as when light passes through a curved shape such
as a cornea or lens.

Refraction: The art of measuring the refractive error of the eye. Also,
a synonym for refractive error.

Refractive error: The eyeglass prescription needed to correct your
vision. Refractive error has three parts: sphere (how nearsighted or
farsighted you are), cylinder (how much astigmatism you have), and
axis (the angle of your astigmatism).

Refractive surgery: Any type of surgery that changes the focusing
power of the eye in order to correct a refractive error. Prelex is a type
of refractive surgery that corrects the eye's focusing ability by
exchanging the lens of the eye.

Regression: A potential complication of Lasik in which the vision
tends to drift back, or regress, toward its original refractive error.

Retina: The light-sensitive layer of cells on the inner back surface of
the eye that processes light and functions much like film in a camera.
The retina converts light into electrical impulses, which are
transmitted along the optic nerve to the brain, which in turn interprets
the impulses as images.

Secondary membrane: haze forms in the lens capsule after removal
of natural lens. Develops months to years after Prelex.

Sclera: The tough "white" of the eye that makes up five- sixths of the
outer layer of the eyeball. Along with the cornea, it protects the
eyeball.

Scleral expansion bands (SEBs): Used in surgical reversal of
presbyopia, these thin silicon bands are implanted in the sclera to

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