Donor age and factors related to endothelial cell loss 10 years after penetrating keratoplasty: Specular Microscopy Ancillary Study

Abstract

Objective: To examine the effect of donor age and other perioperative factors on long-term endothelial cell loss after penetrating keratoplasty (PKP).

Design: Multicenter, prospective, double-masked clinical trial.

Participants: We included 176 participants from the Cornea Donor Study cohort who had not experienced graft failure ≥ 10 years after PKP for a moderate risk condition (principally Fuchs' dystrophy or pseudophakic/aphakic corneal edema).

Methods: Corneas from donors 12 to 75 years old were assigned to participants using a randomized approach, without respect to recipient factors. Surgery and postoperative care were performed according to the surgeons' usual routines. Images of the central endothelium were obtained preoperatively and at intervals for 10 years postoperatively. Images were analyzed by a central image analysis reading center to determine endothelial cell density (ECD).

Main outcome measures: Endothelial cell density at 10 years.

Results: Among study participants with a clear graft at 10 years, the 125 who received a cornea from a donor 12 to 65 years old experienced a median cell loss of 76%, resulting in a 10-year median ECD of 628 cells/mm(2) (interquartile range [IQR], 522-850 cells/mm(2)), whereas the 51 who received a cornea from a donor 66 to 75 years old experienced a cell loss of 79%, resulting in a median 10-year ECD of 550 cells/mm(2) (IQR, 483-694 cells/mm(2); P adjusted for baseline ECD = 0.03). In addition to younger donor age, higher ECD values were significantly associated with higher baseline ECD (P<0.001) and larger donor tissue size (P<0.001). Forty-two of the 176 participants (24%) had an ECD of <500 cells/mm(2) at 10 years and only 24 (14%) had an ECD of >1000 cells/mm(2).

Conclusions: Substantial cell loss occurs in eyes with a clear graft 10 years after PKP, with the rate of cell loss being slightly greater with older donor age. Greater preoperative ECD and larger donor tissue size are associated with higher ECD at 10 years.

Figure 1. A. Endothelial Cell Density at Ten Years versus Baseline for Eyes with a Successful Graft at 10 Years (N=176)

CI = confidence interval. B. Endothelial Cell Density at Ten Years versus Five Years for Eyes with a Successful Graft at 10 Years (N=141) CI = confidence interval.

Figure 2. Endothelial Cell Density Over Time for Participants with a Successful Graft at 10 Years According to Donor Age

Boxplot of endothelial cell density (ECD) according to 2 donor age groups 12 to 65 and 66 to 75 years). Black dots denote mean values, horizontal lines in the boxes are medians, and the bottom and top of the boxes represent the 25^th and 75^th percentiles.

Figure 3. A. Ten-year Endothelial Cell Density by Donor Age for Eyes with a Successful Graft at 10 Years (N=176)

CI = confidence interval. B. Percent Change in Endothelial Cell Density from Baseline to Ten Years by Donor Age for Eyes with a Successful Graft at 10 Years (N=176) CI = confidence interval.

Figure 4. Median Endothelial Cell Loss from 0 to 5 years and 5 to 10 years in Eyes with Successful Graft at 10 Years