Donor Tissue

Younger donor tissue with high endothelial cell counts is ideal but often not possible due to tissue availability. Infant donor tissue (<2 years old) is not recommended as the corneal tissue is thinner and therefore makes wound closure more difficult as well as the risk of progressive ectasia and steep corneal curvatures [28]. Death to preservation time, storage to use time, or method of storage has not been shown to have any effect on graft survival [48]. There is still controversy whether HLA matching has any benefits on immune allograft rejection and graft survival [22, 47]. However, ABO matching may have some benefit [47].

Intraoperative Considerations

Penetrating keratoplasty is performed under general anesthesia. The surgery is technically more difficult as the infant eye is smaller and the palpebral fissure is narrower. Occasionally, a lateral canthotomy may be required to improve surgical access.

Although similar to adult penetrating keratoplasty, certain important surgical modifications are required. A smaller sized graft is required, usually 6–7 mm, but occasionally smaller, to avoid sutures encroaching onto the limbus [40]. This will also keep the graft/host margin away from the limbus that may prevent peripheral anterior synechia from forming. Oversizing the donor tissue by 0.5–1.0 mm is recommended as this assists in wound closure as well as increasing anterior chamber depth [49]. The donor corneal button should be prepared prior to excising the host anterior chamber. An intracameral miotic should also be instilled if lensectomy is not planned to protect the crystalline lens.

The risk of lens extrusion and suprachoroidal hemorrhage is increased in infant keratoplasty secondary to decreased scleral rigidity and increased posterior vitreous pressure (Fig. 7.1) [11, 40]. It is important to use a Flieringa ring or an equivalent to stabilize the globe, taking care not to inadvertently perforate the thin infant sclera (Fig. 7.2) [13]. The suture ends may be left long and taped to the drapes. Superior and inferior rectus bridle sutures may offer additional control of the globe. Other techniques include the use of non-depolarizing muscle relaxants to eliminate the risk of extraocular muscle contraction during the surgical procedure; positioning the patient in a slight head down position; controlled hyperventilation; intravenous mannitol 20% (0.5–1.5 g/kg), and preoperative ocular massage [18, 36, 41].

As the infant cornea is thinner and more pliable than in adults, suturing and tissue apposition is more difficult [11]. Once the recipient corneal button has been excised, it is important to suture the donor button efficiently. Preplaced mattress bridge sutures may be placed before trephination and used to hold the donor cornea in place while it is positioned and cardinal sutures placed [37]. To prevent postoperative pupillary block, peripheral iridectomies (PIs) should be performed. In Peter’s anomaly, where there may be preexisting iridocorneal adhesions, it is important to perform four PIs. In this circumstance, PAS are likely to form, and the PIs tend to