Postoperative Corneal Edema Treatment & Management

Updated: Mar 03, 2016
  • Author: Michael Taravella, MD; Chief Editor: John D Sheppard, Jr, MD, MMSc  more...
  • Print
Treatment

Medical Care

Medical therapy of PBK consists of attempting to minimize corneal edema and the associated symptoms of discomfort and poor vision. Patients with early mild corneal edema may benefit from the use of hypertonic agents, such as sodium chloride 2% and 5% solution and ointment. These agents work by creating a hypertonic tear film, thereby drawing water out of the cornea. Because evaporation from the tear film is minimal at night with the eyes closed (therefore, the tears are less hypertonic), corneal edema tends to be worse in the morning. Use of hypertonic sodium chloride 5% ointment at night applied to the conjunctival cul-de-sac limits this build-up of edema. Use of hypertonic solutions in the morning also helps eliminate some of this nightly fluid accumulation. Some clinicians even recommend a gentle hair dryer to the cornea in the morning to accelerate corneal deturgescence and therefore improved vision.

A typical regimen is Muro 128 2-5% drops used hourly in the affected eye until noon (4-5 times). As the day progresses, evaporation from the tear film begins to create relative hypertonicity of the tears, drawing fluid from the cornea. This accounts for the typical history of improving vision toward the end of the day.

Other practical methods of limiting corneal edema in eyes with borderline endothelial function include treatment of both ocular inflammation and elevated intraocular pressure (see Pathophysiology, Causes) if present.

Bandage contact lenses may be useful as an adjunct to medical treatment for the temporary relief of corneal pain and discomfort. They act to shield the cornea and epithelium from the eyelid. In general, thin, high-water content lenses are tolerated best because they are more oxygen permeable. However, contact lens wear, especially overnight wear, can be associated with increased corneal edema due to improper fit (tight lens) and an increased risk of infection in an already compromised cornea. Patients for whom a bandage lens is prescribed should be treated with a broad-spectrum antibiotic (eg, Polytrim, Azasite) or an aminoglycoside 2-4 times a day. These patients require close follow-up care. Long-term use of a bandage lens for the treatment of this condition is not advised.

Patients who have poor visual potential and severe pain sometimes can benefit from anterior stromal puncture. [37] A 25-gauge needle is used to place multiple small superficial punctures in the affected area of the cornea. The depth of the puncture site is just at or below the Bowman layer. The epithelium subsequently scars firmly over the treated area. This often results in resolution of bullae and pain relief. A bandage lens should be placed over the cornea for 1-2 weeks to allow the epithelium to adhere to the underlying cornea. Excimer laser phototherapeutic keratectomy has also been used to achieve this effect, as has epithelial debridement or lamellar keratectomy.

Finally, amniotic membrane in the form of a free graft protected by a bandage CTL or a ring-mounted contact lens (ProKera, BioTissue) can provide adjunctive benefits through intrinsic wound healing and growth factors, as well as anticollagenolytic and antimicrobial properties.

Next:

Surgical Care

Definitive treatment of PBK and ABK is a corneal transplant. [38, 39] Corneal transplantation is indicated when vision is decreased significantly by corneal edema or when pain becomes intractable. Although a complete discussion of corneal transplantation is beyond the scope of this article, certain unique aspects of corneal transplantation in this setting should be emphasized. First, the size of the graft should be as large as practical without increasing the risk of placing the graft too close to the limbus, thereby increasing the risk of graft rejection. This generally means a donor graft size of 8.00-8.50 mm. Increasing the donor graft size means that more of the healthy endothelium is transplanted. In addition, grafts with higher initial cell counts, 2500-3000 cells/mm2, are desirable for the same reason.

Another important consideration is the management of a preexisting intraocular lens. [40, 41, 42, 43]

Closed-loop anterior chamber intraocular lenses and iris clip style lenses should be removed because of their high association with continued endothelial cell loss and the potential harm to the donor cornea. Special techniques have been devised to remove the often scarred and embedded haptics of closed-loop anterior chamber intraocular lenses with the goal of minimizing iris and angle trauma and associated bleeding.

In general, well-positioned and appropriately sized flexible haptic anterior and modern posterior chamber intraocular lenses can be safely left in the eye. If replacement is anticipated, 5 options are currently available to the surgeon. These options include the following: (1) using a modern flexible loop anterior chamber intraocular lens, (2) placing a posterior chamber lens in the ciliary sulcus, (3) suturing a posterior chamber lens to the iris, or (4) suturing a posterior chamber lens in the sulcus. A fifth option is externalizing the haptics of a posterior chamber intraocular lens, inserting them under scleral flap into and scleral tunnel, and gluing the flap over the haptic as described by Argawal et al. [44] Often, the presence of anterior and posterior synechiae, iridodialysis, large peripheral or sector iridectomies, and glaucoma helps to determine the choice. Implantation techniques begin with careful removal of any anterior displaced vitreous and an equally careful lysis of iris synechiae.

Flexible haptic anterior chamber lenses should be reserved for those eyes with minimal anterior segment pathology, less than 90° of angle synechiae, and well-controlled intraocular pressure. [45, 46] Determining the correct width to implant is essential in preventing complications, such as iris tuck and ovaling (too large), as well as spinning or displacement of the lens (too small). Generally, the width chosen should correspond to a measurement of the horizontal white-to-white corneal diameter plus 1 mm. If inspection of the ciliary sulcus through gentle retraction of the iris reveals an intact and adequate capsular rim, then a posterior chamber intraocular lens can be inserted in the sulcus without suturing the lens in place. [47]

Sutured-in intraocular lenses generally should be reserved for eyes with extensive anterior segment pathology, lack of iris support for an anterior chamber lens, lack of anterior capsular support for a sulcus lens, or glaucoma in which any further compromise of the angle may be anticipated to worsen the control of intraocular pressure. [48]

These 2 techniques are comparable in terms of results. Suturing a lens to the iris is technically easier than suturing a lens in the sulcus and has the added advantage of putting the iris on stretch, which may help to limit synechiae formation. However, once sutured, the iris no longer can be dilated and the retina easily examined. Suturing a lens in the ciliary sulcus places the haptics and lens optic in the most physiologic position; however, this technique is associated with a risk of lens tilt, bleeding from the ciliary body and uvea, and increased open sky surgical time with its inherent increased risk of a choroidal effusion or hemorrhage. Externalizing the haptics of a 3-piece intraocular lens has gained popularity; however, this can be a time-consuming and difficult technique to master for novice surgeons.

Many different variations of these techniques have evolved, and special intraocular lenses with eyelets placed on the haptics to aid suture placement are available. It is up to the individual practitioner to determine which of these lens implant options is most appropriate for a given patient; however, it is important to note that no study to date has clearly pointed to an advantage of one technique or style of intraocular lens replacement in terms of corneal transplant survival, vision, or development of secondary complications (eg, glaucoma).

A relatively new development in cornea transplantation has been the advent of DSAEK (Descemet Stripping Automated Endothelial Keratoplasty) and endothelial keratoplasty. Melles, Terry, Price, and Gorovoy have all been significant contributors to the development and refinement of this technique of endothelial replacement. [49, 50, 51, 52, 53]

The surgery begins by stripping off and removing a sheet of the patient's central endothelium (Descemet stripping). A posterior lamellar disc is prepared by placing a donor cornea in an artificial anterior chamber and cutting it with a microkeratome (the automated part). The donor disc is folded and inserted into the eye, where it is subsequently deployed and elevated up against the patient's cornea with an air bubble. The bubble is then partially removed after a few minutes, leaving the donor disc in place. [54]

A newer variation of endothelial keratoplasty is called Descemet membrane endothelial keratoplasty (DMEK). In this procedure, only Descemet membrane and endothelium from a donor is used to replace the recipient endothelium. DMEK offers quicker visual recovery, better best-corrected vision, and a decreased risk of rejection as opposed to Descemet stripping (automated) endothelial keratoplasty (DSAEK). However, the technique has not gained wide acceptance yet because of perceived difficulties in manipulating the Descemet membrane when it is separated from the overlying carrier disc of corneal tissue and increased risk of complications such as dislocation and tissue wastage. [55, 56] Furthermore, preparation of donor tissue for DMEK surgery is a challenging upgrade for eye banks.

Advantages of endothelial keratoplasty techniques over traditional keratoplasty include quicker visual recovery, preservation of the natural topography and prolate corneal contour, and a much smaller incision, with improved wound strength, comparable to that seen with small-incision cataract surgery. The patient's own corneal curvature is preserved, with less induction of astigmatism. Disadvantages include the potential for dislocation of the donor disc, a problem more frequently encountered during the surgeon's learning curve. Visual acuity can be reduced by hazing or opacification of the lamellar interface between the donor disc and the patient's posterior corneal stroma. It is also more difficult to deploy the donor cornea disc in the presence of a preexisting anterior chamber lens, since there is less room for the disc to unfold. Finally, the method of insertion can significantly damage the donor corneal endothelium, and the best technique for insertion remains a point of contention among surgeons. [57]

Previous