Using the techniques for visualizing stromal dissection depth as described in chapter 2, deep anterior lamellar keratoplasty procedures were performed in a series of 8 patients, after an Institutional Review Board-approved informed consent was obtained from each patient.

In recipient eyes, a self-sealing side port was made at the 9 o clock limbus, to aspirate the aqueous using a blunt canula, and to completely fill the anterior chamber with air. The air-to-endothelium interface was used to visualize the corneal thickness, as has been previously described. At the 12 o clock midperipheral cornea, a 30 gauge needle attached to a syringe filled with viscoelastic (Hydroxypropylmethylcellulose, Ocucoat, Storz, Clearwater, FL, USA), was inserted into the stroma and advanced toward the central cornea (Figure 5.1a). The intended depth of the needle was reached by advancing the needle toward Descemets membrane, until the dark band in between the tip of the needle and the specular light-reflex at the air-to-endothelium interface, i.e. the unincised corneal tissue, had disappeared (Figures 5.1a, 5.2a and 5.2b).

Figure 5.1: Diagrammatic representation of the visco-dissection deep, anterior lamellar keratoplasty technique. (a) After insertion of a needle into the recipient cornea to just anterior to Descemets membrane, (b) viscoelastic is injected to separate Descemets membrane from the posterior stroma, and (c+d) an anterior corneal lamella is trephinated and excised. (e) After stripping its Descemets membrane, a full-thickness donor button is sutured into the recipient bed. Compare to Figures 5. 2a-f. (Source: Cornea 2000;19:427-432).

When the tip of the needle appeared to touch the light-reflex, i.e. the posterior corneal surface, viscoelastic was injected into the cornea, to separate Descemets membrane from the overlying posterior stroma (Figures 5.1b and 5.2c). After a corneal pocket filled with viscoelastic was created, approximately 9.0 mm in diameter, a 7.0 or 7.5 mm Hessburg-Barron suction trephine was centered over the anterior corneal surface (Figures 5.1c and 5.2d). The trephine blade was turned downward until the stromal pocket was just entered, i.e. until viscoelastic was seen to escape from the pocket through the trephine incision. Remaining, unincised stromal attachments were cut with curved microscissors, the anterior corneal lamella was removed, and the recipient bed was thoroughly irrigated to remove all viscoelastic and debris (Figures 5.1d, 5.2e and 5.2f).

Figure 5.2: Preparation of the recipient bed in a human eye bank eye, using the visco-dissection lamellar keratoplasty technique. (a) The anterior chamber has been filled with air. In between the blade tip and the specular light-reflex at the air-to-endothelium interface (white open arrow), a dark band is visible, that reflects unincised posterior corneal tissue. (b) The dark band decreases in width when the needle approaches Descemets membrane. (c) After injecting viscoelastic through the needle, Descemets membrane is separated from the posterior stroma and displaced toward the iris. Note the typical reflex (asterisk) that outlines the pocket (arrows) filled with viscoelastic. (d) After trephination, (e) viscoelastic escapes from the pocket, and (f) an anterior corneal lamella (L) is excised while leaving Descemets membrane in-situ (DM). (Source: Cornea 2000;19:427-432).

After removal of Descemets membrane (see chapter 6), the donor button was transferred to the recipient stromal bed, and the donor and recipient corneal surfaces were marked with an eight incision radial keratotomy marker. The button was sutured into the recipient bed with two running, 10-0 monofilament nylon sutures (Alcon, Gorinchem, The Netherlands). The tension of the sutures was adjusted until the anterior corneal surface reflected a spherical image of a Placido-disc held about 3 cm above the recipient eye.
Figure 5.3: Light microscopy of the recipient bed after visco-dissection of Descemets membrane in a human eye bank eye. (a) A dissection level just anterior to Descemets membrane is seen, with complete removal of all stroma. (b) At higher magnification, some residual stromal strands (arrowheads) are visible over Descemets membrane (arrow); the dotted line indicates the junction of Descemets membrane with the posterior stroma (original magnification x10 and x450). (Source: Cornea 2000;19:427-432).
Figure 5.4: Slit-lamp photographs three months after visco-dissected deep, anterior lamellar keratoplasty. (a) Note the characteristic lines in the recipient Descemets membrane. (b) A clear lamellar transplant is visible, with the donor-to-recipient interface at the level of Descemets membrane. (Source: Cornea 2000;19:427-432).