high-risk patients.
Foulks GN. Diagnosis and management of corneal allograft rejection. In: Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 2. Philadelphia: Elsevier/Mosby; 2011:1409–1416.
Kumar NL, Kaiserman I, Shehadeh-Mashor R, et al. IntraLase-enabled astigmatic keratotomy for post-keratoplasty astigmatism: on-axis vector analysis. Ophthalmology. 2010;117(6):1228–1235.
Skeens HM. Management of postkeratoplasty astigmatism. In: Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 2. Philadelphia: Elsevier/Mosby; 2011:1397–1408.
Verdier DD, Farid M, Garg S, et al. Penetrating keratoplasty procedures. In: Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 2. Philadelphia: Elsevier/Mosby; 2011:1335–1366.
Pediatric Corneal Transplantation
Corneal transplantation in infants and children presents special challenges. Improvements in pediatric anesthesia and the recognition that development of amblyopia is a major impediment to useful vision have led to earlier surgical intervention. Increased understanding of the special problems associated with pediatric grafts, advances in surgical methods, and improved postoperative management have enhanced the prognosis following corneal transplantation. However, the success rate of pediatric transplantation is still guarded and in many cases depends on the extent of coexisting ocular abnormalities. For example, one of the most common indications for pediatric keratoplasty is Peters anomaly. In type I disease, with a central corneal opacity and a normal anterior segment, the survival rate for a clear graft in 1 large series (mean follow-up time of 78 months) was reportedly 83%–90% depending on the age of the patient at the time of surgery. By contrast, in another large series of patients with either type I or type II Peters anomaly, the outcomes were significantly worse: only 56% of grafts remained clear at 6 months and 44% remained clear at 3 years. In type II disease, characterized by adhesions among the cornea, iris, and lens; corneal neovascularization; glaucoma; cataract; and corneal staphyloma, more extensive surgery is required; so not surprisingly, the survival rate of the transplant decreases.
The success of the procedure depends on the family’s dedication to following a rigorous postoperative regimen, including repeated examinations under anesthesia and adherence to the medication regimen, as well as the primary diagnosis. Postoperative glaucoma, strabismus, selfinduced trauma, and immune rejection are extremely common. Before surgery, the physician must reserve time to discuss with the family the many difficult issues associated with surgery, including significant risks, high costs, loss of time from work (with associated loss of income), the extensive ongoing care required by the child, disruption of home life, and less time to attend to other dependents.
Corneal grafting in children younger than 2 years is associated with rapid neovascularization, especially along the sutures. As the wound heals, erosions may occur along the sutures, leading to eye rubbing, epithelial defects, vascularization, and mucus accumulation. Suture erosion, which requires suture removal, has been reported to occur as early as 2 weeks postoperatively in infants.
In general, suture removal is best performed in the operating room for pediatric cases. Until all sutures are removed in infants or young children, frequent examinations are required. Early fitting with a contact lens (as early as the time of PK) and ocular occlusive therapy are necessary to stem development of amblyopia in children with monocular aphakia.
As lamellar surgery has become more popular in the adult population, DALK may be an option for certain pediatric patients with stromal scarring without any other corneal pathology. For disease that is primarily endothelial, such as congenital hereditary endothelial dystrophy (CHED), EK has been reported to provide good outcomes, as observed in a small series of 15 eyes in 8 patients. Some
surgeons favor the use of a keratoprosthesis in pediatric patients who have experienced previous graft failures, have undergone multiple surgeries, or have inflamed eyes. Keratoprosthesis is discussed later in this chapter.
Busin M, Beltz J, Scorcia V. Descemet-stripping automated endothelial keratoplasty for congenital hereditary endothelial dystrophy. Arch Ophthalmol. 2011;129(9):1140–1146.
Rao KV, Fernandes M, Gangopadhyay N, Vemuganti GK, Krishnaiah S, Sangwan VS. Outcome of penetrating keratoplasty for Peters anomaly. Cornea. 2008;27(7):749–753.
Zaidman GW, Flanagan JK, Furey CC. Long-term visual prognosis in children after corneal transplant surgery for Peters anomaly type I. Am J Ophthalmol. 2007;144(1):104–108.
Corneal Autograft Procedures
The greatest advantage of a corneal autograft is the elimination of allograft rejection. Although cases with clinical circumstances appropriate for autograft are uncommon, an astute ophthalmologist who recognizes the possibility of a successful autograft can spare a patient the risk of long-term topical corticosteroid use and the necessity of lifelong vigilance against rejection.
A rotational autograft can be used to reposition a localized corneal scar that involves the pupillary axis. By making an eccentric trephination and rotating the host button before resuturing, the surgeon can place a paracentral zone of clear cornea in the pupillary axis. The procedure is particularly useful in children, who have a poorer prognosis for PK, and in areas with tissue scarcity.
A contralateral autograft is reserved for patients who have a unilateral corneal opacity with a favorable prognosis for visual recovery and a clear cornea in the opposite eye with a coexisting severe dysfunction of the afferent system (eg, retinal detachment, severe amblyopia). The clear cornea is transplanted to the first eye, and either it is replaced with the diseased cornea from the first eye or an allograft, or the eye is eviscerated or enucleated. Such bilateral grafting carries the risk of bilateral endophthalmitis.
Keratoprosthesis
Some patients have an extremely guarded prognosis for corneal transplantation because of a history of multiple graft failures or associated ocular surface disease, as seen with chronic bilateral inflammation from Stevens-Johnson syndrome or pemphigoid. These patients may be good candidates for a synthetic keratoprosthesis. Claes Dohlman, a pioneer in the development of the keratoprosthesis, divides these high-risk patients into 2 groups: those with a good blink reflex and wet eye and those with significant conjunctival scarring, dry eye, and exposure. In the first group of patients, the Boston Type I KPro (Massachusetts Eye and Ear Infirmary, Boston) works well (Fig 1512). Another option is the AlphaCor keratoprosthesis (Addition Technology, Sunnyvale, CA), which is used less frequently because it requires a 2-stage procedure and has had problems with retention. For patients with end-stage dry eye, the Boston Type II KPro is an option. Other types of keratoprostheses are also available for these high-risk patients, such as the TKPro, which uses tibia bone tissue, and the osteo-odonto-keratoprosthesis, which uses dentine and alveolar bone tissue.
Figure 15-12 Boston Type I keratoprosthesis. (Courtesy of James J. Reidy, MD.)
The prognosis with a keratoprosthesis has improved dramatically because of innovations in the design of keratoprostheses and a better understanding of the postoperative management of these patients. The use of a soft contact lens and long-term prophylactic antibiotics has reduced the incidence of infection and breakdown of tissue around the keratoprosthesis. In a large multicenter study of 136 eyes, the retention rate with the Boston Type I KPro was 95% at 8.5 months, and in a second, single-center study of 40 eyes, the retention rate was 83% at 19 months. In the multicenter study, the most common complications of keratoprosthesis implantation were retroprosthetic membrane (24.8%), high IOP (14.8%), vitritis (4.9%), and retinal detachment (3.5%). Less common complications included necrosis of tissue around the synthetic device and macular edema.
Bradley JC, Hernandez EG, Schwab IR, Mannis MJ. Boston Type I Keratoprosthesis: the University of California Davis experience. Cornea. 2009;28(3):321–327.
Dolman CH, Barnes S, Ma J. Keratoprosthesis. Part XI. In: Krachmer JH, Mannis MJ, Holland EJ, eds. Cornea. 3rd ed. Vol 2. Philadelphia: Elsevier/Mosby; 2011:1689–1709.
Pujari S, Siddique SS, Dohlman CH, Chodosh J. The Boston Keratoprosthesis Type II: the Massachusetts Eye and Ear Infirmary experience. Cornea. 2011;30(12):1298–1303.
Zerbe BL, Belin MW, Ciolino JB; Boston Type 1 Keratoprosthesis Study Group. Results from the Multicenter Boston Type 1 Keratoprosthesis Study. Ophthalmology. 2006;113(10):1779.