The corneal endothelium after keratoplasty for keratoconus

Background The aim was to assess the corneal endothelium, post-operative visual outcome and complications following keratoplasty for keratoconus. Methods Seventy-six corneal grafts (57 per cent penetrating keratoplasties and 43 per cent deep anterior lamellar keratoplasties) were assessed as part of routine follow-up at the Ophthalmology Department at Gartnavel General Hospital in Glasgow. Routine ophthalmic assessment included visual acuity, slitlamp biomicroscopy and scanning slit confocal microscopy of the central cornea. Case records were reviewed and demographic, surgical and post-operative data retrieved. Linear and logistic regression models were used to determine associations between endothelial cell density, visual acuity and post-operative complications. KaplanMeier analysis was used to estimate the probability for grafts to retain more than 700 endothelial cells per mm2 and to have 0.3 logMAR or better vision. Odds ratios were calculated to assess the risk for low cell counts and poor visual outcome. Results The mean and standard deviation of the endothelial cell count was predictably higher in lamellar (2033 +/- 643 cells per mm2) than penetrating keratoplasties (898 +/- 380 cells per mm2) and the mean post-operative cell count for grafts without post-operative complications was higher (1585 +/- 775) than those with complications (1312 +/- 747 cells per mm2). Mean visual acuity was 0.25 +/- 0.20 and 0.29 +/- 0.41 for lamellar and penetrating keratoplasties, respectively. A higher number of post-operative events was associated with an increased risk for graft rejection (odds ratio 2.40, p = 0.008, multiple logistic regression) and with poorer visual outcome (odds ratio 1.38, p = 0.044). After keratoplasty, the visual outcome and endothelial cell density were not associated, either in penetrating or deep anterior lamellar grafts (p > 0.05). Conclusions In keratoplasties performed for keratoconus, visual outcome cannot be predicted reliably by post-operative endothelial cell density but post-operative events can lead to poorer visual outcomes in both types of grafts.