Corneal hysteresis in patients with corneal pathologies

Abstract

Purpose: To investigate the corneal hysteresis (CH), the corneal resistance factor (CRF) and the corneal compensated intraocular pressure (IOPcc) of subjects with normal corneas and with corneal pathologies with the Ocular Response Analyzer (ORA). Methods: IOP was measured using Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT) and ORA in 102 subjects with normal corneas and in patients with keratoconus (KC, n=32), Fuchs endothelial corneal dystrophy (FD, n=34) and penetrating keratoplasty (KP, n=50). Additionally central corneal thickness (CCT) and CH were quantified. Results: CH and CRF were significantly reduced in all groups with corneal pathologies in comparison to the normal group (CH: 7.7 (KC), 8.9 (KP), 7.3 (FD) versus 10.3 (N), CRF: 6.4 (KC), 9.3 (KP), 8.2 (FD) versus 10.8 (N) mmHg). High significant differences were also observed in mean IOP between the control group and the groups with corneal pathologies. There was a significant correlation between CH and CCT for normal corneas and corneas with KC and KP. Conclusions: CH and CRF are significantly decreased in patients with KC, FD and KP compared to subjects with normal corneas. Patients with corneal pathologies showed a substantial variability of mean IOP‐values evaluated by using different methods of IOP‐measurement in comparison to subjects with normal corneas suggesting that corneal properties strongly influence the validity of IOP‐measurements.

Repeatability of corneal biomechanics waveform signal parameters derived from Ocular Response Analyzer in children

“…A higher reduction in CH has been shown in glaucoma patients [9]. A significantly lower CH and CRF was reported in eyes with keratoconus [7]. CH, combined with central corneal thickness, can enhance the diagnosis of glaucoma [8].…”

“…The two basic ORA deprived parameters, corneal hysteresis (CH) and corneal resistance factor (CRF), have been shown to be affected by or associated with several corneal conditions and pathologies [6][7][8][9]. A higher reduction in CH has been shown in glaucoma patients [9].…”