Numerous ophthalmic surgical procedures have been developed for correcting imperfect visual acuity such as myopia or hyperopia. A variety of keratomes have been developed over recent decades, devices for performing corneal resectioning to permit access to inner portions of the cornea, where surgical reshaping may then be used to permanently correct vision defects.
Referring to FIGS. 1 and 2a, a typical prior art resectioning operation will separate flap 6 of corneal (and epithelial) tissue 2 from eyeball 4. The outer layers of cornea and epithelial cells are separated and lifted away to expose the inner layers 12 of cornea 2, and are left attached only as flap 6. Exposed interior layers 12 of cornea 2 will to some extent adjust themselves, or their shape may be altered through further surgical steps, such as laser ablation or subsequent resectioning, to remove a contoured layer of corneal tissue. At the conclusion of the surgical procedure, flap 6 is typically replaced over inner corneal tissues 12 to protect the healing tissues.
However, most such surgical reshaping is not reversible, resulting in some risk of creating permanent visual aberrations for the patient. A known alternative is to surgically prepare an opening in the cornea of an eye having visual abnormalities, and to insert a lens therein. Such surgery is difficult to perform accurately. Moreover, the lenses which are available for such vision correction are not entirely satisfactory for a variety of reasons, including a tendency to shift out of position after placement, to impair transcorneal gas diffusion, to be excessively thick, or to be unable to correct presbyopia or astigmatism.
Accordingly, there exists a need for a method and device for correcting visual abnormalities through surgical implantation of an appropriate corrective lens within the cornea an eye in such a way that the lens may be reliably placed and will remain properly positioned and oriented, to enable reversible correction of a wide range of visual abnormalities.