Descemet's stripping automated endothelial keratoplasty (DSAEK) is becoming the treatment of choice for corneal endothelial failure due to its better preservation of the globe's integrity, typically faster visual rehabilitation and more predictable visual outcomes compared with conventional penetrating keratoplasty.1 Nonetheless, as with any ocular surgery, intraoperative and postoperative complications can occur. Taking appropriate preventive measures and being aware of potential complications and their optimal management can greatly increase the chances of a favorable postoperative outcome. This article discusses how to prevent these complications and how best to handle them if they do occur.
Intraoperative complications
Endothelial damage during donor graft preparation
During the donor preparation with the microkeratome, the artificial anterior chamber should be filled with sufficient storage media and the excess conjunctiva on the corneoscleral rim removed prior to sealing the artificial anterior chamber to minimize endothelial damage. A sufficiently large scleral rim is necessary to obtain an adequate seal on the artificial anterior chamber. Chamber collapse can be prevented by using continuous positive pressure and inverting the artificial anterior chamber when dismounting the donor tissue. For storing precut tissues, it is recommended that the anterior lamellar cap be kept in place and the tissue used immediately to reduce endothelial cell loss.2
Paracentral trephination
An eccentric donor trephination can result in an optically and mechanically compromised graft. Furthermore, if the punched area goes into the thicker peripheral tissue, the resulting thickened edge can interfere with graft attachment, leading to an increased risk of decentration and dislocation.3,4 In order to help center the cut, the edges of the stromal side of the donor tissue can be marked with ink prior to trephination. If the decentered cut has already been made and is sufficiently large, the tissue can be repunched slightly eccentrically. To prevent severe endothelial damage, make sure the graft has been cut through completely before disassembling the trephine.
Retained Descemet's membrane
DSAEK is most often performed for edematous corneas, which can obscure visualization and complicate stripping of Descemet's membrane. Incomplete removal of the recipient's Descemet's membrane may result in persistent edema, graft detachment and eventual graft failure.4 In cases of refractory postoperative corneal edema, anterior segment optical coherence tomography (ASOCT) is useful for detecting the presence of residual Descemet's membrane. If it is detected, waiting several months for edema to resolve is not beneficial and a repeat DSAEK with the removal of the residual Descemet's membrane may be warranted.
Air in the posterior segment
An air bubble is injected into the anterior chamber to push the donor graft against the recipient stromal bed to promote graft attachment. However, maintenance of air in the anterior chamber is challenging in aphakic eyes, pseudophakic eyes with an open posterior capsule and eyes that have undergone trabeculectomy (Figure 1) or received glaucoma drainage implants. If air does escape to the posterior chamber, angle-closure glaucoma and endothelial damage can occur because the lens and iris are pushed towards the cornea. In these cases, the patient should be kept in a strict supine position and longer-lasting, higher-buoyancy gases, such as SF6, used.5