Corneal Optical Densitometry in the Evaluation of 2-Year Graft Function Following Endothelial Keratoplasty

Abstract

This study aimed to assess clinical application of the Scheimpflug corneal tomography for objective evaluation of corneal optical density in eyes undergoing Descemet's stripping endothelial keratoplasty (DSEK). In this prospective study, 39 pseudophakic eyes with bullous keratopathy were enrolled. All eyes underwent primary DSEK. Ophthalmic examination included best corrected visual acuity (BCVA) measurement, biomicroscopy, Scheimpflug tomography, pachymetry, and endothelial cell count. All measurements were taken preoperatively and within a 2-year follow-up period. Gradual BCVA improvement was observed in all patients. After two years, the mean and median BCVA values were 0.18 logMAR. A decrease in central corneal thickness was noted only during the first 3 months postoperatively and was followed by a gradual increase. Corneal densitometry decreased constantly and most significantly in the first 3 months postoperatively. The consecutive decrease in endothelial cell count of the transplanted cornea was most significant during the first 6 months postoperatively. Six months postoperatively, the strongest correlation (Spearman's r = -0.41) with BCVA was found for densitometry. This tendency was maintained throughout the entire follow-up period. Corneal densitometry is applicable for objective monitoring of early and late outcomes of endothelial keratoplasty, showing a higher correlation with visual acuity than pachymetry and endothelial cell density.

Keywords: Descemet stripping endothelial keratoplasty; Scheimpflug system; corneal densitometry; corneal optical density; corneal transparency.

Figure 1

Consort flow-chart. postop, postoperatively.

Figure 2

Manual densitometry measurement.

Figure 3

Example of slit-lamp examinations and densitometry readings before DSEK (preoperatively) and 6 and 24 months postoperatively. preop, preoperatively; mo, months; DSEK, Descemet’s stripping endothelial keratoplasty.

Figure 4

Mean BCVA (A), central corneal thickness (B), densitometry (C), and endothelial cell density (D) during the follow-up period. Boxes show the mean ± SE, squares in the boxes represent the mean, and bars represent the mean ± SD. BCVA, best corrected visual acuity; GSU, grayscale units; preop, preoperatively. Precise measurement estimates are provided in Table S1.

Figure 5

Proportion of patients achieving a BCVA ≤ 0.3 and >0.3 logMAR within the follow-up period. Statistical significance is shown in Table 2. BCVA, best corrected visual acuity.

Figure 6

Percentage of BCVA at the time point of visual stabilization (6 months postoperatively). BCVA, best corrected visual acuity; mo, month.

Figure 7

Spearman’s correlation coefficients between BCVA and other analyzed parameters (densitometry, CCT, and ECD) in the postoperative period. * denotes significant differences (p < 0.05). BCVA, best corrected visual acuity; CCT, central corneal thickness; ECD, endothelial cell density; GSU, grayscale units.