In vivo validation of the new Tonopen AVIA tonometer using manometers placed in the anterior chamber and the vitreous cavity under various vitreous conditions.
OBJECTIVE
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).


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.
Department of Ophthalmology, College of Medicine, Asan Medical Center, University of Ulsan , Seoul , Korea and.
Hyun Seung
HS
Yang
June-Gone
JG
Kim
Hong Seok
HS
Ko
Kyoung Sub
KS
Lee
Hoon Jae
HJ
Won
D000328:Adult; D000867:Anterior Chamber / Q000503:physiopathology*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation*; D014822:Vitreous Body / Q000503:physiopathology; D055815:Young Adult