The Use of Digital Microscopy to Compare the Thicknesses of Normal Corneas and Ex Vivo Rejected Corneal Grafts with a Focus on the Descemet’s Membrane
Table 4
Internal validation: comparison between corneal measurements obtained by manual microscopy only and by digital microscopy on 10 corneas from failed grafts stained with periodic acid-Schiff (PAS).
Corneal measurements
Manual microscopy
Digital microscopy
% Difference
Case 1 (corneal opacities with 01 previous PK rejected)
Total cornea (μm, 10x)
520.00
520.00
0.00
Epithelium (μm, 40x)
5.50
5.51
0.18
Descemet’s membrane (μm, 40x)
7.80
7.70
−1.28
Case 2 (corneal opacities with 01 previous PK rejected)
Total cornea (μm, 10x)
280.00
280.00
0.00
Epithelium (μm, 40x)
20.80
20.87
0.34
Descemet’s membrane (μm, 40x)
4.00
4.07
1.75
Case 3 (Fuchs distrophy with 01 previous PK rejected)
Total cornea (μm, 10x)
370.00
370.00
0.00
Epithelium (μm, 40x)
24.60
24.62
0.08
Descemet’s membrane (μm, 40x)
7.60
7.63
0.39
Case 4 (pseudophakic bullous keratopathy with 01 previous PK rejected)
Total cornea (μm, 10x)
560.00
560.00
0.00
Epithelium (μm, 40x)
50.10
50.16
0.12
Descemet’s membrane (μm, 40x)
10.60
10.61
0.09
Case 5 (pseudophakic bullous keratopathy with 01 previous PK rejected)
Total cornea (μm, 10x)
610.00
610.00
0.00
Epithelium (μm, 40x)
37.70
37.66
−0.11
Descemet’s membrane (μm, 40x)
8.90
8.93
0.34
Case 6 (keratoconus with 01 previous PK rejected)
Total cornea (μm, 10x)
410.00
410.00
0.00
Epithelium (μm, 40x)
63.70
63.73
0.05
Descemet’s membrane (μm, 40x)
4.00
4.03
0.75
Case 7 (pseudophakic bullous keratopathy with 01 previous PK rejected)
Total cornea (μm, 10x)
910.00
910.00
0.00
Epithelium (μm, 40x)
52.40
52.40
0.00
Descemet’s membrane (μm, 40x)
7.90
7.90
0.00
Case 8 (corneal opacities with 01 previous DSAEK rejected)
Total cornea (μm, 10x)
570.00
570.00
0.00
Epithelium (μm, 40x)
41.30
41.30
0.00
Descemet’s membrane (μm, 40x)
7.20
7.26
0.83
Case 9 (keratoconus with 01 previous PK rejected)
Total cornea (μm, 10x)
700.00
710.00
1.43
Epithelium (μm, 40x)
52.85
52.91
0.11
Descemet’s membrane (μm, 40x)
13.80
13.86
0.43
Case 10 (keratoconus with 01 previous PK rejected)
Total cornea (μm, 10x)
390.00
390.00
0.00
Epithelium (μm, 40x)
72.40
72.48
0.11
Descemet’s membrane (μm, 40x)
4.00
4.07
1.75
Mean of 10 cases
value
Cornea total (μm, 10x, mean ± SD)
532.000 (±184.000)
541.000 (±185.000)
0.918
Epithelium (μm, 40x, mean ± SD)
42.140 (±20.523)
42.164 (±20.532)
0.998
Descemet’s membrane (μm, 40x, mean ± SD)
7.580 (±3.132)
7.545 (±3.129)
0.980
μm = micrometer; 10x, 40x = microscope magnification; PK = penetrating keratoplasty; DSAEK = automated endothelial keratoplasty; SD = standard deviation. The Kolmogorov–Smirnov test was used to test the equality of probability distribution, whereas the comparisons of two independent variables were performed using Student’s t-test for continuous variables. Levene’s test was used to analyze homogeneity.
