Intraocular pressure and corneal biomechanics in Fuchs' endothelial dystrophy and after posterior lamellar keratoplasty

Purpose: To evaluate the precision of techniques for measuring intraocular pressure (IOP) in corneas with presumably altered biomechanical properties. Methods: Intraocular pressure was measured with a Goldmann applanation tonometer (GAT), ocular response analyzer (ORA) and dynamic contour tonometer (DCT) in 70 eyes. Thirty-five eyes were normal corneas, 18 eyes had Fuchs' endothelial dystrophy, and 17 eyes had undergone Descemet's stripping automated endothelial keratoplasty (DSAEK) surgery. Corneal hysteresis (CH), corneal resistance factor (CRF) as well as central corneal thickness (CCT) were recorded with the ORA. Results: The measured cornea-corrected IOP using ORA was significantly higher than GAT in all three groups (p<0.001). The DCT differed significantly from the Goldmann only in the Fuchs' group (p=0.04). The Goldmann and DCT showed no significant between-group differences, whereas IOP measured with the ORA was different between groups (p<0.001). CH in the DSEAK group differed significantly from the controls (p<0.001), but there was no significant difference between the DSEAK and Fuchs' groups (p=0.21). CCT did not differ significantly between the DSAEK and Fuchs' group (p=0.47). However, both these groups differed significantly from the controls (p<0.001). Conclusion: Corneal hysteresis and CRF are reduced in Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. GAT and DCT seem to measure IOP correctly in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. Corneal-corrected IOP as measured with the ORA appears to overestimate IOP in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty.