Endothelial morphometric measures to predict endothelial graft failure after penetrating keratoplasty

Abstract

Importance: Endothelial morphometric measures have potential value in predicting graft failure after penetrating keratoplasty.

Objective: To determine whether preoperative and/or postoperative central morphometric measures (endothelial cell density [ECD], coefficient of variation [CV], and percentage of hexagonality [HEX]) and their postoperative changes are predictive of graft failure caused by endothelial decompensation after penetrating keratoplasty to treat a moderate-risk condition, principally Fuchs dystrophy or pseudophakic corneal edema.

Design: In a subset of Cornea Donor Study participants with graft failure, a central reading center determined preoperative and postoperative ECD, CV, and HEX from available central endothelial specular images.

Setting: Cornea Image Analysis Reading Center of the Specular Microscopy Ancillary Study.

Participants: Eighteen patients with graft failure due to endothelial decompensation and 54 individuals matched for most donor and recipient measures at baseline whose grafts did not fail.

Main outcome measure: Change in ECD, CV, and HEX values.

Results: Preoperative ECD was not associated with graft failure (P = .43); however, a lower ECD at 6 months was predictive of subsequent failure (P = .004). Coefficient of variation at 6 months was not associated with graft failure in univariate (P = .91) or multivariate (P = .79) analyses. We found a suggestive trend of higher graft failure with lower HEX values at 6 months (P = .02) but not at the established statistical significance (P < .01). The most recent CV or HEX values, as time-dependent variables, were not associated with graft failure (P = .26 and P = .81, respectively). Endothelial cell density values decreased during follow-up, whereas CV and HEX appear to fluctuate without an apparent trend.

Conclusions and relevance: Endothelial cell density at 6 months after penetrating keratoplasty is predictive of graft failure, whereas CV and HEX appear to fluctuate postoperatively, possibly indicating an unstable endothelial population in clear and failing grafts.

Trial registration: clinicaltrials.gov Identifier: NCT00006411.

Figure 1

Box plot of Morphometric ECD over Time in Graft Failures Due to Endothelial Decompensation (n=18) and in Non-Failures (n=54)

Figure 2

Box plot of Coefficient of Variation of Cell Area over Time in Graft Failures Due to Endothelial Decompensation (n=18) and in Non-Failures (n=54)

Figure 3

Box plot of Percent Hexagonality over Time in Graft Failures Due to Endothelial Decompensation (n=18) and in Non-Failures (n=54)

Figure 4

Morphometric parameters (Coefficient of Variation and Percent Hexagonal Cells) at Baseline vs. Donor Age Note: Plots of 5 year morphometric values versus donor age illustrated similar relationship.