A review of randomized controlled trials of penetrating keratoplasty techniques

To assess the effects of variations in operative technique on the outcomes of penetrating keratoplasty (PK).

Systematic literature review of published randomized controlled trials of operative techniques in PK.

Visual acuity, refractive error, endothelial cell density, graft rejection, intraocular pressure (IOP), and other surgical complications.

Twenty-seven trials were identified. Many involved small numbers, some of which were probably compromised by inadequate statistical power. There was some limited evidence from a small number of studies (usually 1 or 2) for preoperative cauterization of the cone in keratoconus, excimer laser trephination, taking into account the effect of trephine sizing on postoperative IOP, taking into account the effect of trephine sizing on postoperative spherical equivalent, using sodium hyaluronate, avoiding vitrectomy if possible, using an iris-fixated posterior chamber lens implant in the absence of capsular support, and adjusting a single continuous suture intraoperatively if used. However, there was little convincing evidence for choosing interrupted suturing versus continuous suturing or for an effect of suturing on final sutures-out astigmatism. Likewise, there was no convincing evidence for the superiority of any lamellar alternative to PK for deep stromal disease. Overall, most of the effects of changing technique were small, and there was no evidence for the superiority of any specific technique in terms of improved quality of life or cost-effectiveness.

There is a need for further studies with which to refine decision-making as regards the choice of operative techniques in PK.