The peripheral zone is the roughly annular region of the cornea outside of the central zone and inside of the limbal zone. Light passing through the peripheral zone is not image forming and can only increase glare and reduce image contrast. The limbal zone is the annular region of the cornea outside of the peripheral zone. Within the limbal zone, which is generally beyond the reach of corneal topography instruments, surface shape is rapidly changing and cornea opacity is rapidly increasing. Refractive Surgery .
Refractive surgery alters the anterior cornea in an attempt to correct vision.
No matter how this is done, two different surgical zones arise. The visual zone is the central region where the new surface is targeted to exactly follow the prescribed correction. The surrounding transition zone blends the optically required visual zone into the existing peripheral cornea.