Corneal complications of glaucoma surgery

Abstract

Most glaucoma surgery can adversely affect the cornea. This often consists of mild endothelial loss on specular microscopy, but occasionally corneal decompensation may occur. The effect on the cornea also depends on preexisting corneal disease, severity and chronicity of intraocular pressure elevation, prior intraocular procedures and complications. With the exception of aqueous shunts, glaucoma procedures are not known to result in progressive endothelial cell loss. Corneal problems are most common after aqueous shunts, especially in children, in which tube-endothelial touch is common. However, other corneal effects of glaucoma surgery have also been reported. Antiproliferative drugs have a toxic effect on endothelium that may be reduced by concurrent use of viscoelastics. Subconjunctival mitomycin C injection may cause limbal stem cell deficiency. In combined phacoemulsification and trabeculectomy, a one-site approach induces less endothelial trauma than two sites. Overhanging blebs may induce corneal dissection, and even decompensation. Descemet's membrane detachment has been reported after nonpenetrating glaucoma surgery, although less endothelial loss is induced than after trabeculectomy. Corneal complications are commonest in patients with aqueous shunts, and long-term prospective studies of endothelial cell density are required to elucidate the factors that predispose to corneal endothelial cell loss.