Stromal and/or epithelial edema due to multiple etiologies may occur throughout the post-operative period (Table 11-1). Edema due to surgical trauma and acute endothelial decompensation from underlying dystrophy, as well as epithelial edema due to elevated intraocular pressure (IOP), may be seen early. Toxic substances inadvertently introduced into the anterior chamber can also cause acute endothelial dysfunction as well as early diffuse corneal edema, referred to as toxic anterior segment syndrome (TASS; discussed later in this chapter). Late postoperative inferior corneal edema may occur because of small nuclear fragments retained in the anterior chamber angle. These fragments may be noticed on initial postoperative examinations, or they may be identified up to years later if they migrate into the anterior chamber from a secluded location in the posterior chamber. Vitreocorneal touch or adherence may contribute to persistent corneal edema after cataract surgery complicated by vitreous prolapse. Significant chronic corneal edema from loss of endothelial cells results in bullous keratopathy (discussed later in this chapter), which is associated with reduced vision, ocular irritation, foreign-body sensation, epiphora, and occasionally infectious keratitis.
In its early stages, corneal edema after cataract surgery can be managed with topical hypertonic drops, corticosteroids, and/or aqueous suppressants. A bandage (therapeutic) contact lens may be used if necessary. Edema from surgical trauma generally resolves completely within 4–6 weeks. When epithelial edema is due to elevated IOP, lowering the pressure medically or via aqueous release from the paracentesis site often results in rapid resolution.
Table 11-1 Principal Causes of Corneal Edema After Cataract Surgery
Removing all vitreous from the anterior chamber during complicated cataract surgery decreases the risks of corneal edema as well as cystoid macular edema (CME) and retinal detachment. When vitreous prolapse with corneal touch or incarceration in the wound is recognized postoperatively and corneal edema or CME develops, an anterior vitrectomy or Nd:YAG laser vitreolysis may be indicated. In more advanced cases with prolonged corneal edema, keratoplasty combined with vitrectomy may be indicated.
Brown-McLean syndrome, a condition of unknown etiology after intracapsular cataract extraction (ICCE) (and, in rare instances, extracapsular cataract extraction [ECCE] or phacoemulsification), is characterized by peripheral corneal edema with a clear central cornea. The edema usually starts inferiorly and progresses circumferentially, sparing the central 5–7 mm. Central cornea guttae frequently appear, and punctate brown pigment on the endothelium often underlies the edematous areas. In rare cases, Brown-McLean syndrome progresses to clinically significant central corneal edema.
Incision and wound complications
Intraoperative incision complications are discussed in Chapter 10 in this volume.
Signs of postoperative wound leakage include decreased vision, hypotony, corneal striae, shallow anterior chamber, hyphema, choroidal folds, choroidal effusion, macular edema, and optic nerve edema. A Seidel test, ultrasound biomicroscopy, or anterior segment optical coherence tomography (OCT) may help diagnose or confirm subtle cases. Small leaks in the early postoperative period may be asymptomatic and self-limited.
Medical treatment may include prophylactic topical antibiotics, cycloplegia, aqueous inhibitors, patching, decreased or discontinued corticosteroid therapy, or a collagen shield or bandage contact lens. Surgical repair is indicated in more serious cases with persistent shallowing of the anterior chamber, iris prolapse, prolonged hypotony, choroidal effusion, or macular edema. Suturing of the wound is usually sufficient, but an amniotic membrane graft or tissue adhesives such as cyanoacrylate or hydrogel glue may be used.
A wound leak under a conjunctival flap may lead to an inadvertent filtering bleb, which may require surgical intervention. Efforts to promote wound healing and cicatrization of the bleb include cryotherapy, diathermy, chemical cauterization with trichloroacetic acid, or injection of an autologous blood patch. In chronic cases, it may be necessary to excise the bleb/conjunctiva and search for a fistula, which can be scraped free of invading epithelium or excised and covered with a scleral patch graft if necessary, followed by resuturing of the wound.
Late postoperative wound dehiscence may be spontaneous or secondary to trauma. Smaller incisions have decreased the occurrence of wound dehiscence. Traumatic wound rupture is often accompanied by extrusion of intraocular contents and almost always requires urgent surgical repair.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.