Clinical aspects and treatment of immune reactions following penetrating normal-risk keratoplasty

Abstract

Endothelial graft rejection is one of the most common causes of graft failure following penetrating keratoplasty (PK). The aim of this study was to evaluate the incidence, time course and outcome of treatment of graft rejection after normal-risk PK and to identify possible risk factors for the recurrence of immune reactions and irreversible graft failure. The study included 500 eyes from the prospective Erlanger Normal-risk Keratoplasty Study with a mean follow-up of 42 +/- 18 (median 40) months. Indications for PK were keratoconus in 48 %, Fuchs' dystrophy in 30 %, secondary bullous keratopathy in 11 %, non-vascularized corneal scars in 7 % and stromal dystrophies in 4 %. Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection and then regularly in a defined examination raster in an cornea out-patient service. During follow-up 29 eyes (5.6 %) developed an episode of endothelial graft rejection (23 eyes with acute diffuse and 6 eyes with chronic focal rejection type). Episodes of endothelial graft rejection clustered between 11 and 25 months postoperatively (15 from 29, 51.7 %). Most grafts (25 of 29) regained clarity after topical and systemic steroid treatment. Only 4 patients showed an irreversible graft failure requiring a repeat PK, all of whom had secondary bullous keratopathy as the primary indication for PK. Risk factors for irreversible graft failure were pre-existing anterior synechiae in 3 patients and secondary open angle glaucoma in pseudoexfoliation syndrome in one patient. Recurrence of graft rejection was seen in 5 patients (all with keratoconus) after a time interval of 8 to 12 months. Under very low topical steroid treatment no further recurrence was observed in all 5 patients up to 2 years. Patients should be followed-up on a regular base for longer postoperative periods, since most episodes of graft rejection were observed between 1 and 2 years after PK. Development of irreversible graft failure was strongly associated with pre-existing anterior synechiae and pre-existing glaucoma. Low-dose topical steroid treatment after immunological rejection seems to prevent the recurrence of further graft rejection.