Epithelial downgrowth has been reported as a complication of various forms of ocular surgery, including trabeculectomy, 1 cataract surgery, 2 and penetrating keratoplasty.3 It can result in visual compromise and is difficult to treat, often requiring aggressive surgical means. To the best of our knowledge, epithelial downgrowth has not been reported as a complication of a Seton implant. We report a case of histopathologically documented epithelial downgrowth following insertion of an Ahmed glaucoma implant.
An 84-year-old white woman was first seen in our office in October 1991. Her ocular history was significant for myopic degeneration with posterior staphyloma and primary open-angle glaucoma in both eyes treated with twice-daily 0.5% timolol maleate. Corrected visual acuity was 20/30 OD and 20/40 OS. She had undergone extracapsular cataract extraction and left aphakic approximately 30 years earlier. She required 180° laser trabeculoplasty in her right eye in 1996, followed by a second 180° trabeculoplasty in 1997. She subsequently required a trabeculectomy with mitomycin in the right eye in November 1997, followed by an Ahmed glaucoma implant in April 1998 for uncontrolled intraocular pressure from 30 to 40 mmHg. Her visual acuity had decreased to counting fingers due to a combination of myopic degeneration, glaucoma, and corneal edema from elevated intraocular pressure. Her visual acuity subsequently improved to 20/80 following surgery. Four months after surgery, a retrocorneal membrane was first noted. Six months after implantation, rapid progression of the retrocorneal membrane was noted. In April 1999, 1 year after implantation, she developed band keratopathy, which decreased her visual acuity to counting fingers, and she underwent EDTA chelation therapy in June 1999. Due to progressive corneal opacification resulting in visual acuity of hand motions, the patient required penetrating keratoplasty in January 2000. An iris biopsy involving the retrocorneal membrane was also performed for diagnostic purposes. Histopathologic examination of the corneal specimen showed a bilayer of cells on the endothelium with rounder nuclei typical of epithelial cells (Figure 1). The iris specimen revealed obvious epithelial downgrowth(Figure 2). In July 2000, the retrocorneal membrane recurred. No further diagnostic or therapeutic intervention has been attempted thus far. The patient's intraocular pressure has remained controlled at around 12 mmHg, but her visual acuity has remained at hand motions because of a recurrence of band keratopathy, the retrocorneal membrane, and preexisting ocular abnormalities.
A penetrating keratoplasty specimen shows a bilayer of cells on the endothelium (arrow) with round nuclei typical of epithelial cells.
An iris specimen shows obvious epithelial downgrowth (arrow).
Although it is tempting to conclude that epithelial downgrowth was a result of the Ahmed glaucoma implant, one must remember that this patient had had multiple previous ocular surgical procedures that may have been responsible for, or predisposed her to, this complication. Nonetheless, the chronology of events strongly suggests that the Ahmed implant was indeed responsible. Despite her multiple procedures, she showed no sign of epithelial downgrowth until 4 months after implantation.
Epithelial downgrowth is a rare but important complication of glaucoma shunt procedures. As in this case, it may cause further reduction in vision and require further surgical intervention. Epithelial downgrowth may also potentially occlude the lumen and result in loss of pressure control. Prophylactic steps, such as antimetabolite use over the anterior chamber entry site, may be taken to lessen the likelihood of this complication. Substances other than silicone may deter the adherence of epithelial cells and may be better suited for use in fashioning the tube portion of the implant.4 Further research is warranted to determine the exact cause of this important complication and to determine how to best decrease its incidence. Glaucoma surgeons should be aware of the possibility of epithelial downgrowth following glaucoma shunt procedures.
Corresponding author and reprints: Daniel A. Jewelewicz, MD, Delray Eye Associates, 16201 S Military Trail, Delray Beach, FL 33484 (e-mail: firstname.lastname@example.org).
Jewelewicz DA, Rosenfeld SI, Litinsky SM. Epithelial Downgrowth Following Insertion of an Ahmed Glaucoma Implant. Arch Ophthalmol. 2003;121(2):285-286. doi:10.1001/archopht.121.2.285