Comparison of the corneal biomechanical properties with the Ocular Response Analyzer® (ORA) in African and Caucasian normal subjects and patients with glaucoma
Article first published online: 11 OCT 2011
© 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation
Volume 90, Issue 2, pages e118–e124, March 2012
How to Cite
Detry-Morel, M., Jamart, J., Hautenauven, F. and Pourjavan, S. (2012), Comparison of the corneal biomechanical properties with the Ocular Response Analyzer® (ORA) in African and Caucasian normal subjects and patients with glaucoma. Acta Ophthalmologica, 90: e118–e124. doi: 10.1111/j.1755-3768.2011.02274.x
- Issue published online: 28 FEB 2012
- Article first published online: 11 OCT 2011
- Received on March 11th, 2011. Accepted on August 3rd, 2011.
- central corneal thickness;
- corneal hysteresis;
- intraocular pressure;
- ocular response analyzer
Purpose: To compare corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer® 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.