The use of the Reichert ocular response analyser to establish the relationship between ocular hysteresis, corneal resistance factor and central corneal thickness in normal eyes

PurposeThe aim of this study was to measure ocular hysteresis and corneal resistance factor (CRF), novel methods of analysing ocular rigidity/elasticity and to determine the relationship between central corneal thickness (CCT), hysteresis and CRF in normal subjects.DesignProspective, cross-sectional, clinical trial.ParticipantsThe study included 207 normal eyes.MethodsHysteresis and CRF were measured by the ocular response analyser. The CCT was measured using a hand held ultrasonic pachymeter.Main outcome measuresOcular hysteresis and CRF in normal patients and their relationship with CCT.ResultsThe mean hysteresis was 10.7 ± 2.0 mmHg standard deviation (S.D.) (range 6.1–17.6 mmHg); the mean CRF was 10.3 ± 2.0 (range 5.7–17.1 mmHg). The mean CCT was 545.0 ± 36.4 μm (471–650 μm). The relationship between hysteresis and CCT; CRF and CCT; CRF and hysteresis were significant (p < 0.0001).ConclusionThis study demonstrated that corneal hysteresis increased with increasing CCT, however, the correlation was moderate. It would appear that CCT, hysteresis and CRF may measure different biomechanical aspects of ocular rigidity and are likely to be useful additional measurement to CCT in the assessment of ocular rigidity when measuring intraocular pressure (IOP). This may be of particular importance when trying to correct IOP measurements for increased or decreased ocular rigidity.