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Woman presents with new corneal edema, retrocorneal membrane after lens exchange
In the left eye, a gray-white sheet-like membrane extended from the superotemporal limbal incision onto the corneal endothelium and into the anterior chamber.
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A 79-year-old woman was referred to the Cornea Service for progressive corneal edema and decreased vision in the left eye, which developed in the years after lens exchange.
Medical history included diabetes, cryptogenic cirrhosis status post liver transplant, hypertension, hyperlipidemia and sleep apnea. Ocular history in the right eye was significant for pseudoexfoliation and phacoemulsification with IOL placement, with subsequent lens subluxation, for which she underwent pars plana vitrectomy and IOL exchange with placement of an anterior chamber IOL. Similarly, the left eye had pseudoexfoliation and developed lens subluxation after phacoemulsification with IOL placement. She underwent paras plana vitrectomy and IOL exchange with transscleral fixation of a one-piece hydrophilic acrylic lens. After the lens exchange, she developed persistent trace corneal edema in the left eye. On a subsequent visit, the patient noted decreased vision in the left eye, and there was increased corneal edema with a retrocorneal membrane, which prompted referral to the Cornea Service.
Examination
Best corrected visual acuity was 20/25 in the right eye and 20/80 in the left eye. Pupils were equally reactive without an afferent pupillary defect. IOP was 15 mm Hg in the right eye and 25 mm Hg in the left eye. The conjunctiva of the left eye was white with transscleral polytetrafluoroethylene sutures visible under the nasal and temporal conjunctiva. The right cornea was clear and compact, but the left cornea had 2+ Descemet’s folds and 1+ thickening. A gray-white sheet-like membrane extended from the superotemporal limbal incision onto the corneal endothelium and into the anterior chamber (Figures 1a and 1b). The anterior chamber was deep and quiet, and the iris had transillumination defects. The scleral-sutured one-piece IOL was centered and stable. Funduscopic examination of the left eye revealed slight thickening of the macula but was otherwise unremarkable.
Source: Jarod Santoro, MD, and Naveen K. Rao, MD
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Retrocorneal membrane
The differential diagnosis for a postoperative retrocorneal membrane is limited and includes vitreous prolapse, inflammatory membrane, Descemet’s detachment, and epithelial or fibrous ingrowth. Postoperatively, vitreous in the anterior chamber may appear as a membrane-like sheet and can become incarcerated in a corneal incision. Vitreous would likely have been identified in the initial postoperative period and would not continue to progress inside the anterior chamber. Concurrent pars plana vitrectomy makes vitreous less likely in this patient. Next, a fibrinous inflammatory reaction may form a sheet-like membrane in the anterior chamber. Such postoperative reactions are rare and more common in pediatric patients and those with uveitis. This patient had no history of uveitis or signs of inflammation and showed only slow progression over years. Finally, downgrowth of fibrous or epithelial tissue through traumatic or surgical wounds may appear as a sheet-like membrane in the anterior chamber.
Diagnosis and management
Diagnosis of epithelial downgrowth is usually clinical and confirmed by pathology. On exam, a membrane may be found over the corneal endothelium or on the surface of the iris, beginning in the area of a surgical incision. The presence of a membrane over the iris can be confirmed by placing a spot of argon laser. The area will blanch and whiten if an epithelial membrane has grown over the iris. Other findings may include an irregular pupil and corneal edema overlying the area of downgrowth. In addition, modalities such as specular microscopy, confocal microscopy and anterior segment OCT can be used to support the diagnosis. In this case, OCT showed a hyperreflective layer on the posterior cornea, which can be seen emanating from the old surgical incision (Figures 2a and 2b).
Discussion
Epithelial downgrowth is a rare but potentially progressive and sight-threatening complication of intraocular surgery and trauma. One large retrospective study conducted between 1953 and 1983 by Weiner and colleagues found the incidence of epithelial downgrowth after cataract surgery was 0.08%; however, the incidence is thought to be lower with modern, less invasive cataract surgeries. Most patients with epithelial downgrowth present within 1 year of surgery or trauma with symptoms of decreased visual acuity, hyperemia and pain. The sequela of epithelial ingrowth includes secondary glaucoma, pupillary block, corneal edema and vision loss.
Epithelial downgrowth is thought to occur when epithelial cells are implanted in the eye by penetrating trauma or surgery or when conjunctival tissue invades into the anterior chamber through delayed or inadequately closed corneal or scleral wounds. The membranes can grow to occlude the trabecular meshwork, causing secondary glaucoma. Further, they may block the flow of nutrients in the aqueous into the cornea and disrupt normal endothelial function, causing overlying corneal edema, ulcers and band keratopathy.
Historical treatments of epithelial downgrowth have consisted primarily of surgical excision. More recently, transcorneal cryotherapy as well as transcorneal and endoscopic photocoagulation have been attempted. Intracameral 5-fluorouracil (5-FU) has also been used as an adjunct to surgical excision of epithelial membranes. 5-FU is a thymidylate synthase inhibitor that blocks synthesis of pyrimidine thymidine, which is a nucleoside required for DNA replication. 5-FU is ideal as it targets only the actively proliferating cells of the epithelial downgrowth. With any treatment approach for epithelial downgrowth, corneal endothelial compromise is likely, and the patient may require penetrating or endothelial keratoplasty for corneal rehabilitation. Extensive disease is related to poorer outcomes. However, early detection and early intervention can improve outcomes.
Clinical course
At the initial visit, the patient was started on hypertonic saline ointment at night and drops four times daily. Slit lamp photos and anterior segment OCT were obtained to document the baseline size and location of the membrane. One month later, the membrane had extended farther nasally, and the corneal edema had worsened. Band keratopathy was developing temporally. The decision was made to proceed with surgery, and the patient underwent EDTA chelation, excision of the epithelial membrane, Descemet’s stripping automated endothelial keratoplasty and injection of intracameral 5-FU. The entire clinically visible membrane was excised, but a focal area of adhesion to the superior iris was noted postoperatively. One week after the surgery, a membrane began to reappear at the superior pupil margin. This recurrent membrane grew over the next 3 weeks, so the patient was taken back to the operating room for repeat excision of the membrane and intracameral 5-FU injection.
At the most recent follow-up, the DSAEK graft remains clear and compact, with no corneal edema on the host, and there has been no recurrence of the retrocorneal membrane or the band keratopathy. The patient’s best corrected vision is 20/100 in the left eye with an IOP of 18 mm Hg.
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- For more information:
- Jarod Santoro, MD, and Naveen K. Rao, MD, can be reached at New England Eye Center, Tufts University School of Medicine. 800 Washington Street, Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Adam T. Chin, MD, and Omar Dajani, MD. They can be reached at the New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.