Abstract
Purpose::
To report corneal biomechanics in patients with Fuchs’ endothelial dystrophy, keratoconus, post-penetrating keratoplasty, and post-endothelial keratoplasty.
Methods::
Patients seen in the cornea clinic of the Duke University Eye Center who had their corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer (ORA; Reichert; Depew, NY) in 2006 were identified. From these patients, the subset with corneal pathology or post keratoplasty was selected. The population was analyzed with descriptive statistics.
Results::
A total of 19 eyes were studied. This population consisted of 7 eyes with Fuchs’ dystrophy without prior surgical intervention, 3 eyes with keratoconus without prior surgical intervention, 3 eyes with Fuchs’ dystrophy and penetrating keratoplasty (PKP), 3 eyes with keratoconus and prior PKP, 1 eye with Fuchs’ and prior Descemet's Stripping Endothelial Keratoplasty (DSEK), and 2 eyes with bullous keratopathy and prior DSEK. For Fuchs’ dystrophy without prior surgical intervention, the mean CH value was 8.85 mmHg (SD=2.78 mmHg, range 6.03 to 14.63 mmHg), and the mean CRF in these patients was 9.40 mmHg (SD=2.62 mmHg, range 7.7 to 15.13 mmHg). For keratoconus without prior surgical intervention, the mean CH value was 9.60 mmHg (SD=1.68 mmHg, range 7.77 to 11.07 mmHg), and the mean CRF in these patients was 9.17 mmHg (SD=3.48 mmHg, range 5.27 to 11.95 mmHg). For Fuchs’ dystrophy and PKP, the mean CH value was 7.33 mmHg (SD=1.57 mmHg, range 6.23 to 9.13 mmHg), and the mean CRF in these eyes was 8.41 mmHg (SD=2.39 mmHg, range 5.97 to 10.75 mmHg). For keratoconus and prior PKP, the mean CH was 12.20 mmHg (SD=1.46 mmHg, range 10.57 to 13.4 mmHg), and the mean CRF was 12.94 mmHg (SD=1.34 mmHg, range 11.4 to 13.8 mmHg). For Fuchs’ and prior DSEK, the CH was 7.03 mmHg and the CRF was 7.7 mmHg. For bullous keratopathy and prior DSEK, the mean CH was 7.07 mmHg (SD=0.33 mmHg, range 6.83 to 7.3 mmHg), and the mean CRF was 8.15 mmHg (SD=2.66 mmHg, range 6.27 to 10.03 mmHg). As a reference, the published normal value for CH is 11.19 and for CRF is 10.46.
Conclusions::
We found corneal hysteresis and corneal resistance factor values to be lower in patients with Fuchs’ endothelial dystrophy (with and without surgical intervention), keratoconus, and bullous keratopathy after DSEK. However, after penetrating keratoplasty, our keratoconus patients had higher than normal CH and CRF. Future studies with larger numbers of patients are needed to confirm these findings.
Keywords: cornea: clinical science • keratoconus • transplantation