more than 3.00 D from the intended correction. Complications included irregular lamellar resection, wound dehiscence, and postoperative corneal edema. Although the procedure was originally intended to be used in conjunction with cataract extraction for the correction of aphakia, the complexity of the procedure and the unpredictable refractive results could not compete—in the early 1980s—with aphakic contact lenses or the improved technology of intraocular lens (IOL) implantation. Homoplastic keratophakia is now largely obsolete.

Alloplastic Corneal Inlays

Alloplastic inlays offer several potential advantages over homoplastic inlays, such as the ability to be mass-produced in a wide range of sizes and powers that can be measured and verified. Synthetic material may have optical properties that are superior to those of tissue lenses.

For insertion of the inlay, a laser in situ keratomileusis (LASIK)–type flap or a stromal pocket dissection can be performed; such procedures are technically easier than doing a complete lamellar keratectomy. Experiments performed in the early 1980s resulted in corneal opacities, nonhealing epithelial erosions, and diurnal fluctuation in vision because fluid and nutrients were blocked from reaching the anterior cornea. Thus, to allow for the transfer of fluid and nutrients to the anterior cornea, microperforations were incorporated into the inlays. Because of work performed by Knowles and others, most subsequent studies used water-permeable hydrogel implants. Hydrogel lenses have an index of refraction similar to that of the corneal stroma, so these lenses have little intrinsic optical power when implanted. To be effective, they must change the curvature of the anterior cornea.

Currently, 3 companies are beginning to commercialize such products. A new device, the Kamra inlay, formerly known as the AcuFocus Corneal Inlay (AcuFocus Inc, Irvine, CA), is undergoing US Food and Drug Administration (FDA) clinical trials for use in the treatment of presbyopia but is currently available in several other countries. This device is composed of an ultrathin (5-µm), biocompatible polymer that is microperforated to allow improved nutrient flow. The 3.8-mm- diameter inlay has a central aperture of 1.6 mm and is generally implanted in the nondominant eye. A 200-µm-thick corneal flap or intrastromal pocket is created, and the inlay is placed on the stromal bed, centered on the pupil. Although the inlay has no refractive power, the central aperture functions as a pinhole to increase depth of focus and improve near vision without changing distance vision. See Chapter 12 for further discussion of corneal inlays.

Ismail MM. Correction of hyperopia with intracorneal implants. J Cataract Refract Surg. 2002;28(3):527–530.

Epikeratoplasty

To eliminate the complexity of the lamellar dissection and intraoperative lathing of early keratomileusis procedures—in which a corneal cap was dissected from the eye, shaped on a cryolathe, and then repositioned with sutures—Kaufman, Werblin, and colleagues developed epikeratoplasty (also called epikeratophakia) in the early 1980s. Epikeratoplasty involved suturing a preformed homoplastic lenticule directly onto the Bowman layer of the host cornea (Fig 4-1). Because no viable cells existed in the donor tissue, classic graft rejection did not occur. Epikeratoplasty was originally intended to create a “living contact lens” for patients with aphakia who were unable to wear contact lenses. Indications for this procedure were later expanded to include hyperopia, myopia, and keratoconus, but problems such as adherence of the grafted tissue, infection, epithelial ingrowth into the bed, poor predictability of results, and corneal edema have relegated epikeratoplasty to a historical footnote. In treating patients with these conditions, surgeons need to