DALK versus PK for keratokonus

Advanced keratoconus usually leads to keratoplasty in young adult patients who have a long life expectancy. Repeat keratoplasty is known to be associated with shorter graft survival compared with primary graft and increased risk of glaucoma that may result in progressive loss of vision. For these reasons, keratoplasty in keratoconus should aim not only to provide patients with good vision but also to permit long‐term survival of the graft. Recent studies have raised controversies regarding survival of penetrating and deep anterior lamellar keratoplasties. In two large series of keratoplasties, graft survival was higher in PK than in DALK eyes. Conversely, a meta‐analysis recently showed that DALK is associated with lower risk of rejection and lower risk of failure compared with PK . These findings make sense if we consider the absence of endothelial rejection and the high survival rate of the corneal endothelium observed in DALK eyes. DALK and PK appear to give similar visual recovery at least in the short and mid‐term. It is not yet possible to determine which technique is associated with the highest chance of maintaining good vision in the long term. This issue depends not only on maintenance of graft transparency but also on corneal biomechanics. Progressive thinning of the peripheral inferior recipient cornea may result in severe irregular astigmatism after keratoplasty for keratoconus. This issue should be further addressed.