In Vivo Validation of the New Tonopen AVIA Tonometer using Manometers placed in the Anterior chamber and the Vitreous Cavity under Various Vitreous Conditions

Abstract

Purpose: To validate intraocular pressure (IOP) measurements using the new Tonopen AVIA® tonometer by comparing values obtained with those measured by manometers placed in the anterior chamber (AC) and the vitreous cavity (VC).

Materials and Methods: Seventy-nine consecutive patients awaiting phacovitrectomy for epiretinal membrane (ERM) or macular hole (MH) (n = 29), vitreous hemorrhage (DMVH) (n = 27) or silicone oil removal (n = 23) were included in this prospective observational study. A clinician masked to patient information performed a complete ophthalmologic examination, including measurements of corneal thickness (CT), AC depth and axial length. Another examiner simultaneously measured conventional IOP using the Tonopen AVIA® (TIOP) and AC and VC IOPs (ACIOP and VCIOP) using two transducers.

Results: The mean TIOP, ACIOP and VCIOP were 16.1 ± 3.8, 16.1 ± 4.4 and 15.5 ± 4.6 mmHg, respectively. There was a good agreement between the TIOP and ACIOP; however, the agreement between TIOP and VCIOP was relatively poor in subgroup analysis. VCIOP was significantly higher than TIOP in the ERM and MH group, with a mean difference of 1.0 mmHg (p = 0.042); however, they were significantly lower in the DMVH group, with a mean difference of −0.7 mmHg (p = 0.026) and in the silicone oil group (mean difference, −2.3 mmHg) (p < 0.0001). In multivariate analysis, TIOP correlated significantly only with CT (p < 0.037) and increased by 2.7 mmHg per 100 μm increase in CT.

Conclusions: IOP measurements using the Tonopen AVIA® tonometer showed good agreement with ACIOP values, although TIOP measurements were affected by CT. However, the VCIOP values using the transducer may have over- or underestimated IOP relative to TIOP and ACIOP under various vitreous conditions. Further validation of VCIOP using a cannular type of manometer should be considered.

• Anterior chamber IOP
• intraocular pressure
• manometer
• tonopen AVIA
• vitreous cavity IOP

Acknowledgements

The authors thank Dr D. H. Lee and J. T. Kim for data collection and management. The authors also thank J. E. Lee for technical assistance.

Notes

*This article was presented at the 108th annual meeting of the Korean Ophthalmological Society, held from 2 November 2012 to 4 November 2012, in Ilsan KINTEX, Kyungkido, Korea.