Evaluation of Corvis ST tonometer with the updated software in glaucoma practice

Abstract

AIM: To evaluate the agreement of biomechanically corrected intraocular pressure (b-IOP) and central corneal thickness (CCT) measurements obtained with the updated Corvis ST tonometer versus Goldmann applanation tonometry (GAT) and optical-based corneal pachymetry (OB-CCT) in controls, patients with ocular hypertension (OHT) and primary open angle glaucoma (POAG). Additionally, we examined the differences in corneal deformation parameters provided by the updated Corvis ST among the three groups. METHODS: For each participant, GAT IOP, OB-CCT and measurements with a Corvis ST with updated software were obtained. Bland-Altman analysis was used to assess the agreement between the two measurement methods. RESULTS: A consecutive series of 80 eyes from 80 participants (30 with POAG, 25 with OHT and 25 normal controls) were included in this prospective study. The mean GAT IOP of all eyes was 17.2±3.6 mm Hg, and the mean b-IOP was 15.9±3.7 mm Hg (Spearman's rho=0.767, P<0.001). The 95% limits of agreement (LoAs) ranged from -3.1 mm Hg to 5.5 mm Hg for GAT IOP and b-IOP. b-IOP was not correlated with OB-CCT (Spearman's rho=-0.13 P=0.917). Meanwhile there was a weak positive corelation between OB-CCT and GAT IOP–b-IOP difference (Spearman's rho=0.378, P=0.001). The mean OB-CCT was 549.5±36.4 µm, and the Corvis-CCT was 556.1±41.5 µm (Spearman's rho=0.900, P<0.001). No statistically significant difference in the new indices provided by the updated Corvis ST was detected among the three groups. Compared with control eyes, POAG eyes had a significantly reduced applanation time 2 after adjusting for OB-CCT and GAT IOP (P=0.048). CONCLUSION: Corvis b-IOP and CCT correlate well with GAT IOP and OB-CCT. b-IOP is not affected by CCT, which might be an advantage, especially in thick or thin corneas. Corvis ST yields shorter applanation time 2 measurements in patients with POAG, which might reflect altered corneal viscoelasticity.

Corneal Biomechanics in Primary Open Angle Glaucoma and Ocular Hypertension: A Systematic Review and Meta-analysis

“…There was no publication bias found in most of the comparisons through Egger tests ( P >0.05), except for the analysis of HC-t in the POAG group ( P =0.040, Table 3). The result indicated that the study of Halkiadakis et al50 contributed to the publication bias, but its exclusion did not change the pooled result (Table 4).…”

“…A total of 1922 records were identified in the electronic databases, 95 of which were included in the systematic review and 31 in the meta-analysis. Eighteen of the 31 articles used ORA to investigate differences in corneal biomechanical parameters between glaucoma patients and normal controls,10,14,24–39 while 15 used CST 11,16,36,37,40–50. The procedure of the literature search and the reasons for exclusion are shown in Fig.…”

“…Eighteen of the 31 articles used ORA to investigate differences in corneal biomechanical parameters between glaucoma patients and normal controls, 10,14,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] while 15 used CST. 11,16,36,37,[40][41][42][43][44][45][46][47][48][49][50] The procedure of the literature search and the reasons for exclusion are shown in Fig. 1.…”

Agreement of intraocular pressure measurement with Corvis ST, non-contact tonometer, and Goldmann applanation tonometer in children with ocular hypertension and related factors

“…Compared to GAT and NCT, CST adequately accounted for corneal biomechanical properties and provided a more comprehensive performance for IOP assessment [6,11,13] . In a study by Halkiadakis et al [30] no correlation was found between CST-IOP and CCT in eyes with OHT, primary open angle glaucoma, or normal eyes. In the present study, CST-IOP and GAT-IOP showed better consistency in the OHT group, non-OHT group, and all subjects compared with NCT-IOP.…”

Comparative analysis of intraocular pressure measured with non-contact air tonometry (Tonopachy NT-530P) and non-contact tonometer with detection of corneal biomechanical response (OCULUS Corvis ST)

“…The results obtained from optical pachymetry were 549.5±36.4 µm on average, and those from Corvis ST-556.41.5 µm, without statistically significant difference. In conclusion, the authors assume that the measured values of IOP and pachymetry between GAT, optical pachymetry, and Corvis ST are comparable, which is useful especially at low and high values of CCT(13). In the Bulgarian literature there is a similar study by Z. Zlatarova and a team comparing the values of IOP and CCT measured with Goldman's applanation tonometry, ultrasound pachymetry, and Tonopachy NT-530P non-contact tonometer.…”