Comparison of Ocular Response Analyzer Parameters in Chinese Subjects With Primary Angle-Closure and Primary Open-Angle Glaucoma

Abstract

Objectives: To evaluate corneal hysteresis (CH) and intraocular pressure (IOP) measured by the Ocular Response Analyzer in Chinese subjects with primary angleclosure glaucoma (PACG), assess their relationship with Goldmann applanation tonometry (GAT) measurements, and compare this with subjects with primary openangle glaucoma (POAG) and normal controls. Methods: In this prospective observational study, consecutive subjects with PACG and POAG without prior intraocular surgery were enrolled from glaucoma clinics. Normal subjects were recruited from an ongoing population-based study. One eye of each subject underwent standardized ocular examination and IOP measurement by GAT and the Ocular Response Analyzer. Corneal hysteresis and cornealcompensated IOP were compared between groups. Results: Of the 443 subjects recruited, 131 had PACG, 162 had POAG, and 150 were normal. Corneal hyster-esis was lower in PACG (9.1 mm Hg; 95% confidence interval [CI], 8.7 to 9.4 mm Hg) and POAG (9.5 mm Hg; 95% CI, 9.2 to 9.5 mm Hg) eyes compared with control eyes (10.4 mm Hg; 95% CI, 10.1 to 10.6 mm Hg; PϽ.001 for both), with no difference (P =.16) in CH found between PACG and POAG eyes. After adjusting for age, sex, and IOP measurement by GAT, CH persisted to be lower only in eyes with PACG in comparison with control eyes (9.4 vs 10.1 mm Hg; P=.006). Eyes with POAG had lower CH than control eyes but the difference was not statistically significant (9.6 vs 10.1 mm Hg; P=.06). Conclusions: Corneal hysteresis was lower in eyes with glaucoma. After adjusting for age, sex, and IOP measurement by GAT, a persistently lower hysteresis was noted in eyes with PACG compared with other groups.

Combining corneal hysteresis with central corneal thickness and intraocular pressure for glaucoma risk assessment

“…1,23 Conversely, it has been suggested that low CH might be expected to increase the risk for developing glaucomatous optic neuropathy, possibly due to reduced capacity of the eyewall to dampen IOP spikes 23,24 and/or reduced ability of optic nerve structures to suitably respond to IOP fluctuations. 1,25,26 This premise is supported by several studies, which indicate that eyes with POAG exhibit lower CH compared with normal eyes [1][2][3][12][13][14][15][16] and eyes with OH. 1,12 In addition, lower CH has been linked to both glaucoma progression 17,18 and severity.…”

“…Recent research has provided evidence that corneal biomechanical properties may have a meaningful influence not only on intraocular pressure (IOP) measurements [1][2][3][4][5][6][7][8][9][10][11] but also on the ocular effects of IOP. [1][2][3][12][13][14][15][16][17][18][19][20][21][22] Central corneal thickness (CCT) has received the most attention in this regard, spurred by findings from the Ocular Hypertension Treatment Study (OHTS) in which CCT was the strongest independent predictor of conversion from ocular hypertension (OH) to primary open-angle glaucoma (POAG).…”

“…[1][2][3][12][13][14][15][16][17][18][19][20][21][22] Central corneal thickness (CCT) has received the most attention in this regard, spurred by findings from the Ocular Hypertension Treatment Study (OHTS) in which CCT was the strongest independent predictor of conversion from ocular hypertension (OH) to primary open-angle glaucoma (POAG). 22 Furthermore, the OHTS investigators reported that after subjects were split into thin, intermediate, and thick CCT subgroups, subjects in the thinnest CCT subgroup were more than three times as likely to develop glaucoma compared with subjects in the thicker CCT subgroup.…”

“…[1][2][3][12][13][14][15][16] Accordingly, identification of a specific CH value that provides good sensitivity and specificity for differentiating eyes with and without glaucoma has been elusive. Because it is a relatively dynamic variable, however, adjusting CH for the factors that influence its variability potentially may foster a more robust relationship between CH and clinical diagnosis.…”

“…These findings agree with many other reports and support accounting for these factors, particularly CCT and IOP, when interpreting CH. [1][2][3][4][5][6][7][8][9][10][11][12]14 This study was therefore designed to examine whether the clinical utility of CH might be enhanced by adjusting CH for the effects of CCT and IOP. To accomplish this goal, we employed a three-step approach.…”