Corneal Deformation Response in Patients With Primary Open-Angle Glaucoma and in Healthy Subjects Analyzed by Corvis ST.

PURPOSE: To compare corneal deformation response between patients with primary open-angle glaucoma (POAG) and healthy subjects. A prevalent case-control study was conducted, followed by an integrated meta-analysis.

METHODS

Primary open-angle glaucoma was confirmed by presence of glaucomatous optic disc damage with corresponding visual field defect after excluding secondary causes. Age-matched controls were recruited. Corvis ST (CST) was used to measure 10 parameters of corneal deformation response and central corneal thickness (CCT). The association between parameters of deformation response and clinical factors was assessed by the linear regression analyses. Differences in deformation response between POAG and healthy subjects were compared after adjusting for other factors. Eligible studies were identified by a systematic search of the PubMed, ISI Web of Science, and Embase databases; Web sites of professional associations; and the Google Scholar engine.

RESULTS

This study included 37 patients with POAG and 36 healthy controls. Significant associations were found between IOP and the first applanation time (A1T), first applanation velocity (A1V), second applanation time (A2T), and second applanation velocity (A2V) in each group. The deformation amplitude (DA), A1V, and A2T were lower in the POAG group, whereas the A1T, A2V and peak distance (PD) were greater in the POAG group than in the healthy controls (all P < 0.05). Ten separate studies plus the present study, involving 691 patients with POAG and 740 controls, were ultimately meta-analyzed. The significant differences in the DA, A1T, and A2T were further confirmed, with pooled weighted mean difference (WMD) of 0.13 mm (95% CI 0.04-0.23; P = 0.008) for A1T, -0.13 mm (95% CI -0.21 to -0.05; P = 0.001) for DA, and -0.46 ms (95% CI -0.70 to -0.22; P < 0.001) for A2T.

CONCLUSIONS

The corneal response parameters provided by CST are informative for the assessment of corneal biomechanics. Patients with POAG showed significantly greater A1T and lower DA and A2T values than healthy controls, indicating a less deformable cornea in POAG patients.