Pediatric Keratoplasty
Graft survival rates in infants and young children are less favorable than in adult transplantations. Most graft failure occurs within the first year after operation. The survival rate has recently been improved significantly with advances in corneal microsurgery and postoperative care ( Table 2 ). Due to the low incidence of pediatric keratoplasty and the necessity of long-term follow-up, most studies have been retrospective. Data derived from these studies are difficult to compare on account of variations in diagnosis, surgical technique, postoperative management, length of postoperative follow-up and the broad range of patient ages at the time of surgery. The indication for surgery appears to be the predictor for graft survival. Certain diagnoses may be associated with a poor surgical outcome. Sclerocornea has been associated with poorer outcomes, which may be secondary to the limbal stem cell deficiency. The variable rates of success for transplants in patients with Peters anomaly depend in part on the severity of the disease and presence of associated congenital glaucoma or extensive anterior-segment abnormalities. In one series, an unusually high percentage (100% of the grafts at 1 year) remained clear but the patients had milder disease and none of them required a concurrent lensectomy vitrectomy or had preoperative glaucoma, which are known risk factors for failure. Several mucopolysaccharidoses have other associated ocular anomalies that negatively influence both surgical and visual outcomes. Furthermore, deposition of metabolic end products may rapidly recur in the donor graft. On the other hand, patients with isolated congenital hereditary endothelial dystrophy or posterior polymorphous dystrophy have an excellent prognosis for penetrating keratoplasty, because of the absence of corneal vascularization or other anterior-segment abnormalities. Additionally, keratoplasty for corneal trauma is generally successful in the pediatric age group, particularly in cases of trauma limited to the anterior segment. Other poor prognostic indicators are bilateral disease, concomitant infantile glaucoma, simultaneous lensectomy and vitrectomy, additional subsequent surgeries, previous graft failure, extensive goniosynechiae, marked corneal vascularization, postoperative complications and, finally, poor postoperative medical compliance.

The visual outcome after pediatric keratoplasty is not always commensurate with what would be expected from observed graft survival rates. Poor visual outcome in a clear graft is well recognized and usually attributed to the development of amblyopia, the presence of coexisting ocular morbidity and postoperative astigmatism. Nonetheless, approximately 50% of infants and young children who undergo penetrating keratoplasty for congenital corneal opacities gain functional vision, which is defined as the ability to count fingers or perform more complex tasks. In some children it has been observed that even with a cloudy graft there has been some visual improvement, which may be from advancing visual development during the period when the graft was clear.