Significant risk of stromal rejection risk after DALK

The authors of this study in the September issue of Cornea retrospectively examined stromal rejection among deep anterior lamellar keratoplasty (DALK) patients and found that 5 of 20 experienced it within 12 months of surgery. They conclude that this incidence is clinically significant and suggests that these patients may benefit from corticosteroid regimens similar to those used following penetrating keratoplasty (PK), with postoperative corticosteroid use continuing for up to 12 months, particularly in those with established risk factors for rejection. They say that stromal rejection after DALK can compromise graft clarity if misdiagnosed or left untreated, but prompt recognition and aggressive treatment can result in good anatomic and visual outcomes.

Furthermore, the authors say, the high incidence of post-DALK stromal rejection in this study suggests that it may be more common in PK than previously reported, with a significant misclassification of either purely stromal or mixed mechanism rejection as endothelial rejection in prior studies.

They reviewed the records of 20 patients who underwent DALK performed by two surgeons during a 15-month period. They found that five patients experienced stromal rejection within 12 months, of whom two were on low-dose corticosteroids when diagnosed. Four of the five patients were treated aggressively with prednisolone acetate 1% eye drops every one to three hours. The fifth patient was treated less aggressively with a maximum dose of prednisolone acetate 1% every six hours and subsequently experienced a second rejection episode less than five months later. All episodes resolved completely with treatment.

The authors say that the fact that two of the five patients were on low-dose corticosteroid eye drops when diagnosed with stromal rejection illustrates that low-dose corticosteroid therapy alone may not be adequate to prevent stromal rejection. This is further supported by the fact that the majority of the patients in the study who did not experience rejection were taking at least prednisolone acetate 1% every day between three and nine months postoperatively. While the study was not sufficiently powered to test this, the authors say it may be prudent to maintain patients on topical corticosteroids, such as prednisolone acetate 1%, at least daily for the first 12 months postoperatively and possibly beyond.