ABSTRACT.Purpose: To compare corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer Ò tonometer (ORA) between (i) African normals and treated primary open-angle glaucoma (POAG) patients and (ii) between normals and treated POAG Caucasians. To analyse the correlation of CH and CRF with visual field (VF) defects in the two groups.Methods: This comparative study included 59 African (29 (POAG), 30 normals) and 55 Caucasians (30 POAG and 25 normals) subjects. Goldmann applanation tonometry (GAT) and ORA measurements were performed in a randomized sequence. Visual field was tested with the Swedish interactive threshold algorithms standard strategy of the Humphrey perimeter. Hoddap classification was used to estimate the severity of VF defects.Results: Primary open-angle glaucoma Africans were younger than POAG Caucasians (p < 0.001). Goldmann applanation tonometry and central corneal thickness (CCT) did not differ significantly between the four subgroups. African normals had lower CH than Caucasian controls (p < 0.001). CH was 9.2 ± 1.1 and 8.3 ± 1.7 mmHg respectively in POAG Caucasians and Africans (p < 0.001). African controls had higher ORA corneal-compensated intraocular pressure (IOPcc) than Caucasian controls (p < 0.001). Primary open-angle glaucoma Africans had higher IOPcc values than Caucasian POAGs (p < 0.001). CH and IOPcc were associated with race (p < 0.001) but not with CCT. Based on mean deviation values (MD), POAG Africans had more severe VF defects. CH was correlated with MD (r = 0.442; p = 0.031) and severity of VF defects only in POAG Africans (r = )0.464; p = 0.013).Conclusions: African normal subjects and POAG patients had an altered CH, which is associated with a significant underestimation of GAT IOP. This may potentially contribute to the earlier development and greater severity of glaucoma damage in Africans compared with Caucasians at diagnosis.

Purpose To evaluate the correlation between visual field index (VFI%) and ganglion cell complex (GCC) parameters: global loss volume (GLV%) and focal loss volume (FLV%) in glaucomatous patients. Methods Prospective study including both eyes of 31 glaucomatous patients with a repeatable abnormal Standard Automated Perimetry (SAP) and a local visual field defect in at least one eye. Visual field (VF) examination was performed using Humphrey SAP. OCT imaging was obtained by an experienced technician and using RTVue Spectral Domain OCT. VFI% from VF examination and GLV% and FLV% from RTVue OCT were taken into account for further statistical analysis. Pearson correlation coefficient was used to assess the correlation between different parameter. Results The mean age was 56 ± 14 yrs. Only 49 of the total 62 visual fields showed reliable and repeatable defect with an abnormal GHT (Abn VF). These VF were taken into account for the correlation test. The remainders (NL VF) were used as controls. The mean VFI% in Abn VF was 79.8 ± 21%. The mean of GLV% was 6.0 ±4.1 and the mean of FLV % was 19.6±11. The Pearson correlation showed no correlation between VFI% and GLV% (p=0.07). There was a correlation between VFI% and FLV% (p<0.01). Conclusion To date, in this interim analysis, we found only a correlation between VFI% and FLV%. It might refer that FLV parameter is more influenced by the focal defect in the VF.