Pascal dynamic contour tonometry versus goldmann applanation tonometry in gas and air-filled eyes after vitrectomy surgery

[Intraocular pressure elevation after vitrectomy-Goldmann applanation tonometry measures lower intraocular pressure than dynamic contour tonometry]

Hintergrund

Das dynamische Konturtonometer PASCAL (DCT) ist ein digitales, der natürlichen Hornhautgeometrie angepasstes Kontakttonometer. Verglichen wurde das DCT mit dem Goldmann-Applanationstonometer (GAT).

Methodik

In einer prospektiven Querschnittstudie wurden 100 Augen vor und nach Pars-plana-Vitrektomie (ppV) vergleichend mit dem GAT und DCT gemessen. Verwendete Endotamponaden waren verschiedene Gase und Silikonöle. Erfasst wurden der präoperative intraokulare Druck (IOD), postoperative Druckveränderungen und die Intertonometerdifferenz.

Ergebnisse

Präoperativ lag der mittlere IOD mit dem GAT gemessen bei 15,8 ± 5,2 mm Hg und dem DCT bei 17,5 ± 5,9 mm Hg. Am ersten postoperativen Tag stieg bei Augen, die mit Gas versorgt wurden, der Druck im Mittel um 2,5 mm Hg (p = 0,035) an. Das DCT erfasste 18 Augen (19,1 %) mit einem postoperativen IOD von ≥ 25 mm Hg. Postoperativ maß das GAT den IOD im Schnitt 2,5 mm Hg niedriger und bei expansiver Gasendotamponade im Mittel um 3,0 mm Hg niedriger als das DCT. Bei IOD-Werten von postoperativ über 20 mm Hg lag das GAT im Mittel 4,7 mm Hg unter dem DCT. Zehn von 18 Augen mit IOD ≥ 25 mm Hg wurden mit dem GAT nicht als hypertensiv (≥ 25 mm Hg) erkannt. Bei 13 % maß das DCT am 1. postoperativen Tag einen um mindestens 6 mm Hg höheren IOD als das GAT. In einem Extremfall wurde der IOD mit dem GAT bei Gasendotamponade um 12 mm Hg unterschätzt.

Schlussfolgerung

Postoperative Druckanstiege nach ppV sind gefürchtete Komplikationen und können zu irreversiblem Visusverlust führen. Abhängig von der verwendeten Endotamponade misst das GAT den IOD niedriger als das DCT – besonders bei Druckspitzen durch expansive Gase. Die postoperative IOD-Messung nach ppV ist bedeutend und die Messwerte von GAT und DCT können abweichen.

Changes in intraocular pressure after intraocular eye surgery-the influence of measuring technique

AIM

To investigate the changes in intraocular pressure (IOP) before and after intraocular surgery measured with Goldmann applanation tonometry (GAT) and pascal dynamic contour tonometry (PDCT), and assessed their agreement.

METHODS

Patients who underwent trans pars plana vitrectomy (TPPV) with or without cataract extraction (CE) were included. The IOP was measured in both eyes with GAT and PDCT pre- and postoperatively, where the non-operated eyes functioned as control.

RESULTS

Preoperatively, mean IOP measurements were 16.3±6.0 mm Hg for GAT and 12.0±2.8 mm Hg for PDCT for the operated eyes. Postoperatively, the mean IOP dropped to 14.3±5.6 mm Hg for GAT (P=0.011) and rose up to 12.7±2.6 mm Hg for PDCT (P=0.257). Bland-Altman analysis showed a poor agreement between GAT and PDCT with a mean difference of 2.9 mm Hg preoperatively and 95% limits of agreement ranging from -3.2 to 9.0 mm Hg. Postoperatively, the mean difference was 1.2 mm Hg with 95% limits of agreement ranging from -8.3 to 10.7 mm Hg. There were no significant differences between the TPPV and TPPV+CE group, except when measured with PDCT postoperatively (P=0.012).

CONCLUSION

The IOP is reduced after surgery when measured with GAT and remained stable when measured with PDCT. However, the agreement between GAT and PDCT is poor. Although PDCT may be a more accurate predictor of the true IOP, it seems less suitable for daily use in the clinical practice.

Comparison of intraocular pressure using Goldmann applanation tonometry versus non-contact tonometry in eyes with high-viscosity silicone oil

BACKGROUND

To compare intraocular pressure (IOP) measurements using Goldmann applanation tonometer (GAT) and air tonometer (non-contact tonometry [NT]) in vitrectomized eyes with high-viscosity silicone oil tamponade, as well as in normal eyes.

PATIENTS AND METHODS

In this prospective comparative study, 32 eyes with silicone oil tamponade of high viscosity (5700 CS) and 32 normal fellow eyes were included. IOP was measured by GAT and air tonometer 30 ± 12 days after vitrectomy, while measurements of central corneal thickness (CCT) were also obtained.

RESULTS

In eyes with silicone oil, IOP was 20.09 ± 4.91 mmHg and 16.75 ± 3.86 mmHg using contact tonometer and air tonometer, respectively (p < 0.0001). In normal eyes, IOP was 16.41 ± 2.15 mmHg and 16.31 ± 2.49 mmHg using the same tonometry techniques and this difference was not statistically significant (p = 0.598). In addition, no significant correlation was detected between IOP measurements using both techniques and age, gender, CCT, and type of lens.

CONCLUSIONS

It seems that GAT overestimates IOP in eyes with high-viscosity silicone oil compared with NT, while both IOP measurement techniques in normal eyes provide similar values. Further assessment of available IOP measurement methods could possibly establish the most accurate technique for IOP estimation in vitrectomized eyes with silicone oil tamponade.

Goldmann Applanation Tonometry versus Dynamic Contour Tonometry after Vitrectomy with Silicone Oil Endotamponade

PURPOSE

To evaluate the agreement of intraocular pressure (IOP) measurements using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with silicone oil endotamponade and controls.

METHODS

In this prospective comparative study, IOP was measured with GAT and DCT in 30 eyes with oil endotamponade 1-3 days after vitrectomy and 40 untreated controls. In addition, ocular pulse amplitude (OPA), corneal pachymetry (CCT), and axial length (AL) were measured.

RESULTS

GAT values in the oil group were significantly higher compared to control eyes (mean GAT oil 13.6 ± 5.1 mmHg; mean GAT control 10.8 ± 2.1 mmHg; p = 0.003). There was no significant difference in DCT measurements (mean DCT oil 12.0 ± 4.1 mmHg; mean DCT control 11.9 ± 2.9 mmHg; p = 0.9). This led to a significant difference of GAT-DCT between the oil and control group (mean difference of GAT-DCT oil 1.6 ± 4.7 mmHg; mean difference of GAT-DCT control -1.1 ± 2.6 mmHg; p = 0.004). The difference between GAT and DCT was negatively correlated with the mean IOP measured by both methods (r = -0.36, p = 0.02) and positively correlated with CCT only in the control group (r = 0.36, p = 0.02), as well as to AL only in the oil group (r = 0.46, p = 0.01). The OPA did not differ significantly between groups.

CONCLUSION

GAT and DCT showed a good agreement in control eyes. The difference of GAT and DCT is significantly changed in eyes after vitrectomy with silicone oil endotamponade. Our findings suggest that GAT overestimates IOP in this situation.

Goldmann Applanation Tonometry Versus Dynamic Contour Tonometry After Vitrectomy

PURPOSE

The aim of the study was to investigate the agreement of intraocular pressure (IOP) measurement using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with intraocular gas endotamponade, in eyes after vitrectomy with no tamponade, and in controls.

METHODS

In this prospective comparative study IOP was measured with GAT and DCT in 41 eyes with gas endotamponade (sulfur hexafluoride 20%) 1 to 3 days after vitrectomy, in 32 postvitrectomy eyes with intraocular water, and in 46 control eyes with no history of glaucoma or intraocular surgery. Corneal pachymetry and axial length measurements were additionally performed.

RESULTS

The mean difference between GAT and DCT (GAT-DCT) in gas-filled eyes was 3.1 mm Hg [SD=6.2 mm Hg], that in eyes after vitrectomy with no tamponade was 0.4 mm Hg (SD=4.8 mm Hg), and in control eyes was 0.4 mm Hg (SD=3.8 mm Hg). No significant correlation was found between the differences of GAT and DCT (GAT-DCT) and the mean IOP of GAT and DCT in water-filled eyes (r=-0.25, P=0.18) and control eyes (r=0.23, P=0.13), but a significant correlation was found in the gas-filled eyes (r=0.71, P<0.0001). A significant correlation between central corneal thickness and the mean difference of both methods was seen only in the control group (r=0.36, P=0.03).

CONCLUSIONS

IOP as determined by DCT underestimates IOP in gas-filled eyes compared with GAT, as GAT values were on average 3.1 mm Hg higher compared with those of DCT. The extent of IOP underestimation using DCT increases with higher IOP values. In the group of eyes after vitrectomy and in normal eyes we found a generally good agreement between the 2 methods, although high interindividual discrepancies were present. Our findings suggest that the 2 devices should not be used interchangeably in IOP evaluation after vitrectomy with gas endotamponade, which remains a difficult challenge.