Glaucoma in Cases of Penetrating Keratoplasty, Lamellar Procedures and Keratoprosthesis

The two main issues that concern glaucoma patients before and after penetrating keratoplasty and posterior lamellar procedures and patients that develop glaucoma after surgery are the risks of graft failure and the aggravation of the glaucoma. Failure of the corneal graft may require regrafting, which increases the risk of developing or aggravating glaucoma, while uncontrolled glaucoma may result in graft failure and further damage to the optic disc and visual field. These two problems may lead to each other creating a vicious circle. They should be treated by glaucoma and corneal specialists or by someone who is expert with both. Glaucoma was found in 10-42% of the patients with a single corneal transplantation, 0-27% of them had preoperative glaucoma.1-6 Preexisting glaucoma was usually a result of an initial insult such as chemical burn or secondary glaucoma. In repeated corneal transplantation, the incidence of postoperative glaucoma was higher (14-47%) than in primary transplantation.7-12 It increases with increased number of regrafts and in aphakia. Corneal graft failure 3 years after keratoplasty occurred in 29-47% when glaucoma was present, compared with 9-30% when it was absent.13,14 Patients requiring penetrating keratoplasty and lamellar procedures (deep lamellar keratoplasty, Descemet's stripping (automated) endothelial keratoplasty, Descemet’s membrane endothelial keratoplasty) may suffer from preexisting various types of open and closed angle glaucomas, which may be primary or secondary. Primary open angle and primary closed angle glaucomas may preexist and corneal surgery may be required for unrelated disorders such as Fuchs’ corneal dystrophy. Secondary glaucomas may occur due to open and closed globe injuries. In those injuries, the glaucoma may be of open angle and caused by obstruction of the trabecular meshwork by red blood cells (from hyphema), ghost cells (ghost cell glaucoma) or tearing of the meshwork (angle recession). It may also be closed-angle caused by peripheral anterior synechiae. Corneal transplantation may also be required in chemical burns especially alkali. In these cases, the cornea may be opaque because of chronic edema and scarring. Secondary glaucoma may also be associated with corneal abnormalities such as anterior mesenchymal dysgenesis (e.g., Peter’s and Axenfeld-Rieger’s anomalies). In these disorders, in addition